Post on 09-Feb-2019
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UNIVERSIDADE DA BEIRA INTERIOR
Ciências Sociais e Humanas
Concurrent resistance and aerobic training follow
a detraining period in elementary school students.
Albano Paulo Jorge Fernandes Rodrigues dos Santos
Tese para obtenção do Grau de Doutor em
Ciências do Desporto
(3º ciclo de estudos)
Orientadores: Prof. Doutor Mário C. Marques
Prof. Doutor Daniel A. Marinho
Covilhã, Novembro de 2011
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University of Beira Interior
Faculty of Social and Human Sciences
Sport Sciences Department
Albano Paulo Jorge Fernandes Rodrigues dos Santos
Concurrent resistance and aerobic training follow
a detraining period in elementary school students.
PhD in Sport Sciences
Promoters:
Professor Mário C. Marques, PhD
Professor Daniel A. Marinho, PhD
University of Beira Interior
Covilhã, Portugal, 2011
i
This document was specially accomplished as original
dissertation for the purpose of obtaining the degree of PhD, in
accordance with the provisions of Portuguese Decree-Law
107/2008 of 25 June.
ii
To my mother’s memory, by the moral and social example
To my close family, by the encouragement and support
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Acknowledgments
The current work was finally accomplished due to the help and collaboration of many
people whom I would like humbly to thank, close colleagues and estimated friends. All of
them have singular great geniality.
To Professor Mário C. Marques, promoter/supervisor of this thesis, close friend and
mentor, thank you for showing me the way for the development of this work. Thank you
for your help and exceptional knowledge. I am very grateful for the support and for all the
lessons taught over the past years.
To Professor Daniel A. Marinho, supervisor of this thesis, close friend and mentor, thank
you for your friendship, help and exceptional knowledge. Thank you for providing all the
necessary conditions for this work to be successfully concluded.
To Professor Aldo Costa, thank you for your altruistic help and fellowship. Thank you for
the relevant advice and encouragement that you always gave me, as well concern about
the development of this work.
To Professor Mikel Izquierdo, thank you for your altruistic help and fellowship. Thank you
for the relevant advice and encouragement that you always gave me and thank you for all
the reviewing and correction of the work.
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To Professors Hugo Louro and Jaime Sampaio, thank you for the loan of the indispensable
research devices.
To Manuela Costeira (the School Principal of EB Poceirão) and her management team for
allowing the use of the training equipment used in studies and school facilities; to Jorge
Romão (the School Principal of EB2,3 Pegões) and his management team for allowing the
use of school facilities, my gratefull acknowledgement.
To my friends Luis Matos, Susana Bernardino, Suse Gonçalves, Jofre Ouro and André
Gouveia; to my students Rita Jesus, Carla Valente, Carla Monteiro, Rui Batista, Carlos
Martins and Bruno Dias thank you for your contribution on data collection.
To my colleagues Carla Martins and Darlene Rosário thank you for English reviewing and
counseling. Your contribution was extremely crucial on articles publishing.
To the children and adolescents that were part of the studies’ samples, thank you for
participating in studies.
To my wife Alexandra, my daughter Leonor and my son Henrique, thank you for being part
of my life, for the affection and for your love. I’m proud of you.
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This thesis is supported by the following publications:
Santos, A., Marinho, D.A., Costa, A.M., Izquierdo, M., Marques, M.C. The effects of
concurrent resistance and endurance training follow a detraining period in elementary
school students. J. Strength Cond. Res. In press. DOI: 10.1519/JSC.0b013e318234e872
Santos, A., Marinho, D.A., Costa, A.M., Izquierdo, M., Marques, M.C. Effects of a concurrent strength and endurance training/detraining program follow a specific detraining cycle on strength and aerobic fitness in school girls. J. Human Kinetics. Special Issue: 93-103, 2011.
Santos, A., Marinho, D.A., Costa, A.M., Izquierdo, Barbosa, T.M., Marques, M.C. Effects of concurrent resistance and endurance training/ detraining programs on pubescent and adolescents physical fitness performance. Study Review. J. Sport Sci. Med. Under revision.
vi
General Index
Acronyms list ................................................................................................................................. x
Thesis resume ............................................................................................................................... xi
Resumo da tese .......................................................................................................................... xii
Introduction .................................................................................................................................... 1
Abstract 1 - Concurrent strength and aerobic training and detraining
programs: effects on pre- early pubescent and post-pubescent children and
adolescents physical fitness performance. Study review. .......................................... 3
Abstract 2 - The effects of school-based resistance training and concurrent
strength and aerobic training programs on untrained boys. .................................... 5
Abstract 3 - The effects of school-based resistance training and concurrent
strength and aerobic training programs on untrained girls. ..................................... 6
Abstract 4 - The effects of detraining period after school-based resistance and
concurrent strength and aerobic training programs on untrained boys. ............ 7
Abstract 5 - The effects of detraining period after school-based strength and
concurrent strength and endurance training programs on untrained girls. ...... 8
Object of study ............................................................................................................................... 9
Aerobic fitness...................................................................................................................................... 10
Muscular strength ................................................................................................................................ 10
Concurrent strength and aerobic training ............................................................................................. 11
Detraining effects ................................................................................................................................. 13
Summary .............................................................................................................................................. 14
General goals ............................................................................................................................... 15
Research problems .............................................................................................................................. 15
Studies’ specific goals .............................................................................................................. 16
Hypotheses ................................................................................................................................... 17
Study One: Concurrent strength and aerobic training and detraining
programs: effects on adolescents’ physical fitness performance. Study review.
........................................................................................................................................................... 19
Methods ................................................................................................................................................ 21
Inclusion and exclusion criteria ...................................................................................................... 21
Search methodology ........................................................................................................................ 21
Cardiorespiratory fitness training ...................................................................................................... 22
vii
Age and growth effects .................................................................................................................... 22
Onset physical fitness level effect ................................................................................................... 24
Gender effects ................................................................................................................................... 25
Program design ................................................................................................................................ 26
Strength training .................................................................................................................................. 27
Age/growth effects .......................................................................................................................... 28
Onset physical fitness level effect ................................................................................................... 33
Gender effects ................................................................................................................................... 34
Program design ................................................................................................................................ 35
Concurrent resistance and aerobic training ...................................................................................... 40
Detraining effects ................................................................................................................................. 42
Discussion ............................................................................................................................................. 44
Study two - The effects of school-based strength training and concurrent
strength aerobic training programs on untrained boys. .......................................... 47
Methods ................................................................................................................................................ 47
Experimental Approach to the Problem ........................................................................................ 47
Subjects ............................................................................................................................................. 50
Testing Procedures .......................................................................................................................... 50
Statistical analyses ............................................................................................................................. 53
Results .................................................................................................................................................. 53
Discussion ............................................................................................................................................. 56
Conclusions .......................................................................................................................................... 59
Study three - The effects of school-based strength training and concurrent
strength and aerobic training programs on untrained girls. .................................. 60
Methods ................................................................................................................................................ 60
Experimental Approach to the Problem ........................................................................................ 60
Subjects ............................................................................................................................................. 60
Statistical analyses ........................................................................................................................... 61
Results .................................................................................................................................................. 61
Discussion ............................................................................................................................................. 63
Conclusions .......................................................................................................................................... 66
Study four - The effects of a detraining period on body composition and
performance variables after school-based strength and concurrent strength
and aerobic training programs on untrained boys. .................................................... 68
Methods ................................................................................................................................................ 68
viii
Experimental Approach to the Problem ........................................................................................ 68
Subjects ............................................................................................................................................. 69
Testing Procedures .......................................................................................................................... 69
Statistical analyses ............................................................................................................................. 69
Results .................................................................................................................................................. 69
Discussion ............................................................................................................................................. 72
Conclusions .......................................................................................................................................... 73
Study five - The effects of a detraining period on body composition and
performance variables after school-based strength and concurrent strength
and aerobic training programs on untrained girls. .................................................... 74
Methods ................................................................................................................................................ 74
Experimental Approach to the Problem ........................................................................................ 74
Subjects ............................................................................................................................................. 75
Testing Procedures .......................................................................................................................... 75
Statistical analyses ............................................................................................................................. 75
Results .................................................................................................................................................. 75
Discussion ............................................................................................................................................. 77
Conclusions .......................................................................................................................................... 79
Overall discussion ..................................................................................................................... 80
Training effects .................................................................................................................................... 81
Detraining effects ................................................................................................................................. 87
Veracity of formulated hypotheses.................................................................................... 90
Conclusions of the five studies ............................................................................................ 92
Study 1 .................................................................................................................................................. 92
Study 2 .................................................................................................................................................. 93
Study 3 .................................................................................................................................................. 93
Study 4 .................................................................................................................................................. 93
Study 5 .................................................................................................................................................. 93
Overall Conclusion .................................................................................................................... 94
Practical Applications .............................................................................................................. 94
References .................................................................................................................................... 96
Appendices ...................................................................................................................................... a
ix
Tables Index
Table 1 - Training program design. ........................................................................................................ 49
Table 2 - Descriptive (mean ± standard deviation) characteristics of the participants during three
testing trials (M1 and M2) for all groups. .............................................................................................. 54
Table 3 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running
Speed and VO2Max at all three test trials (M1 and M2) for each group. ............................................. 55
Table 4 - Descriptive (mean ± standard deviation) characteristics of the participants during three
testing trials (M1 and M2) for all groups. .............................................................................................. 62
Table 5 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running
Speed and VO2Max at all three testing trials (M1 and M2) for each group. ........................................ 63
Table 6 - Descriptive (mean ± standard deviation) characteristics of the participants during three
testing trials (M2 and M3) for all groups. .............................................................................................. 70
Table 7 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running
Speed and VO2Max at all three testing trials (M2 and M3) for each group. ....................................... 71
Table 8 - Descriptive (mean ± standard deviation) characteristics of the participants during three
testing trials (M2 and M3) for all groups. .............................................................................................. 76
Table 9 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running
Speed and VO2Max at all three testing trials (M2 and M3) for each group. ........................................ 77
x
Acronyms list
%BF – body fat percentage
BF – body fat
BMI – body mass index
CMJ – counter movement jump
CMVJ - counter movement jump
CMSLJ - counter movement standing long jump
D – day
DT – detraining
GC – control group
GCOM – concurrent resistance and endurance training
GR –resistance group
M1 – pre-training
M2 – post-training
M3 – end of detraining period
MAV - maximum individual aerobic volume
MB – medicine ball
Med – medicine
PA – physical activity
PE – physical education
RM – repetition maximum
TestM – test at the middle of the period
Wk – week
Wks – weeks
Yrs – years old
xi
Thesis resume
Students involved in physical education classes often perform strength and aerobic training
concurrently in an effort to achieve specific adaptations to both forms of training. However, the
scientific literature has produced inconclusive results. Additionally, interruptions in training process
because holidays are normal situations in school context. This recess can produce a children’s
performance loss. Nevertheless, the detraining period and its consequences are not well reported in
sports literature, and namely during puberty. This is important since the period of strength training
cessation can produce a positive delay transformation rebound in sports specific performance, which
is determinant on school performance evaluation of the student. Therefore, the general objectives of
this thesis were to analyze the effects of strength training alone and concurrent strength and aerobic
training on strength and aerobic performances on a large sample of healthy school subjects; and to
assess the effects of a detraining period on strength, power and aerobic performances. To test our
hypothesis we set 5 studies: 1 study review and 4 experimental studies. One hundred and nine healthy
children (42 boys, 67 girls) recruited from a Portuguese public high school were randomly assigned
into two experimental groups (8 weeks training program) and one control group as follows: one group
performing strength training only (GR); another group performing combined strength and aerobic
training (GCOM); and the third was the control group (GC, no training program). All sample subjects
attended physical education classes twice a week. Strength and aerobic parameters were assessed
prior and after a training program period and post a detraining period as well. From pre- to post-
training period GCOM’s subjects did not take advantage over GR’s subjects in jumps, running speed
and balls throwing tests. VO2max increased significantly in GCOM and remained unchanged in both GC
(except for girls) and GR groups. Concurrent training is an effective, well-rounded exercise program
that can be set up as a means to improve initial or general strength in healthy school non-adult
population; training program effects persists even at the end of detraining period. Future researches
should examine the interference effects arising from the order of strength and aerobic training
exercises program on strength enhancement.
xii
Resumo da tese
Amiúde, as aulas de educação física, fazem apelo ao treino concomitante da força e de resistência
aeróbia. A literatura científica tem produzido resultados inconclusivos acerca desta temática.
Complementarmente, as interrupções do processo de treino devido a períodos de férias são situações
normais em contexto escolar. Estes períodos podem promover perda do desempenho físico. No
entanto, o período de destreino e consequentes efeitos, durante a puberdade/adolescência, não estão
suficientemente estudados na literatura. Assim, os objetivos gerais desta dissertação foram analisar,
em contexto escolar, os efeitos do treino isolado de força e do treino concomitante de força/resistência
aeróbia, na força e na resistência aeróbia numa extensa amostra de jovens em idade e contexto
escolar; determinar os efeitos de destreino sobre a força e resistência aeróbia. Para testar as hipóteses
definidas, definimos 5 estudos: 1 estudo de revisão e 4 estudos experimentais. Cento e nove jovens
saudáveis (42 rapazes; 67 raparigas) recrutados de uma escola pública foram aleatoriamente incluídos
em dois grupos experimentais e num grupo de controlo, da seguinte maneira: um grupo realizou
apenas treino de força, outro realizou treino concomitante de força /resistência aeróbia e um terceiro
grupo serviu de controlo (sem programa de treino). Todos os indivíduos da amostra realizaram
normalmente as aulas de educação física. Os parâmetros de potência muscular e de endurance foram
avaliados antes, após o programa de treino e após 12 semanas de destreino. Durante o período de
treino não se verificaram diferenças significativas entre grupos experimentais no que concerne aos
ganhos de desempenho nos testes de saltos, velocidade e lançamento de bolas. O VO2max aumentou
significativamente no grupo que treinou resistência aeróbia e manteve-se inalterado quer no grupo
que só treinou força (exceto para as raparigas) quer no grupo de controlo. O treino concomitante é,
portanto, eficaz e consubstancia-se como bom programa de treino que pode ser prescrito como meio
de melhoria da força numa população não-adulta e saudável; os efeitos do programa de treino
mantêm-se no final do período de destreino. Estudos futuros devem examinar os efeitos decorrentes
da ordem de aplicação do treino de força e de resistência aeróbia no desenvolvimento da força e da
resistência aeróbia.
Introduction
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Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Introduction
Despite of consensus among several credible organizations as The British Association of
Sport & Exercise Science, (113), The American Academy of Pediatrics (2), The American
College of Sports Medicine (27,65), or the National Strength and Conditioning Association
(41) that strength since appropriately designed and supervised by expert personnel is
beneficial to children and adolescents’ athletic performance, health and fitness, there is a
scarcity of robustly designed studies investigating the main factors which determine
concurrent strength and aerobic training gains and detraining effect (school based) in
untrained children and adolescents. Muscular strength has been recognized as an
important component of fitness in the recent evidence-based physical activity guidelines
for school-age youth (114). Despite there is clear data in adults (65) to support these
positions, evidence-based data in children and adolescents is limited. Additionally, school
is considered the primary societal institution with the responsibility for promoting
physical activity in youth (22,102) and comprehensive school-based programs are
specifically designed to enhance among other fitness components, muscular strength
(36,40). Moreover, complementarily studies that have been properly investigated the
changes in strength training-induced strength gains during detraining in pre adolescents
and adolescents are still scarce and insufficient. Different results have been found on
detraining effect over subject’s strength gains.
These were our onset points to this thesis. Therefore, we implemented five studies to this
dissertation. First study was a literature systematic review and the other four were
empirical studies.
Firstly we present the abstracts of all studies. Then, we framed the origin of the problems
followed by problems definition. We set up the objectives of the thesis and after this step,
Introduction
2
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
circumscription of study hypothesis. Then, each of the five studies was presented. After
that we present a thesis conclusion and, at last, studies that were part of our PhD work
plan.
Introduction
3
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Abstract 1 - Concurrent strength and aerobic training and detraining
programs: effects on pre- early pubescent and post-pubescent children
and adolescents physical fitness performance. Study review.
Beyond habitual physical activity, other factors influence aerobic fitness, including age,
gender, heredity, and medical status. It appears that pubertal status plays the most
significant role in determining the effects of training on VO2max, but there is insufficient
evidence to determine the effects of the training stimulus, particularly due to the lack of
properly documented exercise intensities in past research. The critical stage of maturity
where training may exert its greatest impact remains speculative. On the other hand, it is
largely documented that in addition to aerobic activities, strength training can offer unique
benefits for children and adolescents when appropriately prescribed and supervised.
Comprehensive school-based programs are specifically designed to enhance health-related
components of physical fitness, which include muscular strength. However, strength
school-based programs aiming an increase in physical fitness performance are less studied
and with inconclusive findings. Thus, the aim of this study was to synthesize information
published in English language and to fulfil the following criteria this review included: (i)
experimental studies in children or adolescents samples (aged 10-18 years old); (ii) at
least one exercise intervention investigated endurance, resistance training, either in
isolation or as an adjunct to an alternative treatment. A systematic database search for
full-length manuscripts was performed on Sportdiscus, Springerlink, Taylor & Francis,
Sciencedirect, Wiley interscience, and Pubmed for the 1980–2011 (September week 4)
period. First, five keyword categorical searches were conducted: (i) ‘resistance training’, or
‘strength training’, or ‘weight training’; (ii) ‘child’, or ‘adolescent’, or pediatric; (iii)
‘endurance’, or ‘aerobic’, or ‘cardiorespiratory’, or ‘cardiovascular’, ‘VO2max’, or ‘maximal
aerobic power’; (iv) ‘concurrent’ and (v) ‘detraining’, ‘recess’. The reference lists of each of
Introduction
4
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
these studies and a number of review papers and position stands were manually searched
to extract further studies. Concurrent training seems to be effective in pre-pubescent and
post pubescent boys and girls. It can be assumed that concurrent strength and endurance
training not only do not impair strength or aerobic development as seems to be an
effective, well-rounded exercise program that can be used as a means to improve initial or
general strength in youth. Regarding detraining effects, studies that have been properly
investigated the changes in resistance training-induced strength gains during detraining in
pre adolescents are still scarce and insufficient. However, it can be assumed that even after
a period as long as 3 month, strength and endurance gains can be observed in untrained
early to post-pubescent boys and girls.
Introduction
5
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Abstract 2 - The effects of school-based resistance training and
concurrent strength and aerobic training programs on untrained boys.
The purpose of this study was to compare the effects of an 8-week training period of
resistance training alone (GR), or combined strength and aerobic training (GCOM) on
body composition, muscular strength, and VO2max adaptations in a sample of
adolescent school boys. Forty-two healthy boys recruited from a Portuguese public
high school (age: 13.3 ± 1.04 yrs) were assigned to two experimental groups to train
twice a week for 8 weeks: GR (n = 15), GCOM (n = 15), and a control group (GC: n = 12;
no training program). Significant training-induced differences were observed in 1- and 3-
kg medicine ball throw gains (GR: +10.3 and +9.8%, respectively; GCOM: +14.4 and
+7%, respectively). Significant training-induced gains in the height and length of the
countermovement (vertical-and-horizontal) jumps were observed in both the
experimental groups. Time at 20m speed running decreased significantly for both
intervention programs (GR: -11.5% and GCOM: -12,4%, p=0.00). After training, the
VO2max increased only significantly for GCOM (4.6%, p = 0.01). Performing strength and
aerobic training in the same workout does not impair strength development in
young school boys. As expected, strength training by itself does not improve aerobic
capacity.
Introduction
6
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Abstract 3 - The effects of school-based resistance training and
concurrent strength and aerobic training programs on untrained girls.
The purpose of this study was to compare the effects of an 8‐week-training period of
strength training alone (GR), or combined strength and aerobic training (GCOM) on body
composition, power strength and VO2max adaptations in a schooled group of adolescent
girls. Sixty‐seven healthy girls recruited from a Portuguese public high school (age:
13.5+1.03 years, from 7th and 9th grade) were divided into three experimental groups
to train twice a week for 8 wks: GR (n=21), GCOM (n=25) and a control group (GC:
n=21; no training program). Anthropometric parameters variables as well as
performance variables (strength and aerobic fitness) were assessed. No significant
training‐induced differences were observed in 1kg and 3kg medicine ball throw gains
(2.7 to 10.8%) between GR and GCOM groups. Significant training‐induced gains in
CMVJ (8 to 12%) and CMSLJ (0.8 to 5.4%) were observed in the experimental groups.
Time of 20m significantly decreased (GR: ‐11.5% and GCOM: ‐10%) after treatment
period. After training, VO2max only slightly increased for GCOM (4.0%). Performing
simultaneous strength and a e r o b i c training in the same workout does not appear to
negatively influence strength and aerobic fitness development in adolescent girls.
Indeed, concurrent strength and aerobic training seems to be an effective, well‐rounded
exercise program that can be prescribed as a means to improve initial or general
strength in healthy school girls.
Introduction
7
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Abstract 4 - The effects of detraining period after school-based
resistance and concurrent strength and aerobic training programs on
untrained boys.
The purpose of this study was to compare the effects of 12 weeks of detraining on body
composition, strength, and VO2max adaptations in a sample of adolescent school boys after
8-week of training period of strength training alone (GR), or combined strength and
aerobic training (GCOM). The same forty-two healthy boys recruited from a Portuguese
public high school (age: 13.3 ± 1.04 years) for study two were used. In 1- and 3-kg
medicine ball throw tests, no significant changes were observed after a DT period in both
the experimental groups. Significant training-induced gains were observed in both the
experimental groups. No differences in height and length of the countermovement
(vertical-and-horizontal) jumps were perceived after a DT period. In time at 20m either
GR or GCOM groups kept the running speed after a DT period of 12 weeks. A VO2max
significant loss was observed in GR but not in GCOM. Training programs’ effects persist
even at the end of the 12 wks. of DT period.
Introduction
8
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Abstract 5 - The effects of detraining period after school-based strength
and concurrent strength and endurance training programs on untrained
girls.
The purpose of this study was to compare the effects of 12 weeks of detraining on body
composition, strength, and VO2max adaptations in a sample of adolescent school girls after
8-week of training period of strength training alone (GR), or combined strength and aerobic
training (GCOM). The same sixty‐seven healthy girls recruited from a Portuguese public
high school (age: 13.5+1.03 years, from 7th and 9th grade) for study three were used.
Anthropometric parameters variables as well as performance variables (strength and
aerobic fitness) were assessed. In 1- and 3kg medicine ball throw tests no significant
changes were observed after a DT period in any of the experimental groups. Time of 20m
significantly decreased, whereas only the GR group kept the running speed after a DT
period of 12 weeks. After training period VO2max increased only slightly for GCOM (4.0%).
No significant changes were observed after the DT period in all groups, except to GCOM in
CMVJ and CMSLJ. The detraining period was not sufficient to reduce the girls’ overall training
effects.
Object of study
9
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Object of study
Regular physical activity during childhood and adolescence is associated with improvements
in numerous physiological and psychological variables and it has been extensively
documented in health related outcomes field (93,102,120,121). Recommendation for the
amount of physical activity deemed appropriate to yield beneficial health and behavioural
outcomes for school-age youth have been also widely proposed (93,114,120). As such, this
thesis will focus on performance relating aerobic and muscular fitness, two physical fitness
components (57).
Cardiorespiratory fitness of children aged 13 to 15 years old (yrs) is largely determined by
habitual physical activity level (22,75,120), which tends to reduce with age (30,115).
However, other factors are determinant on cardiorespiratory fitness development, including
age, gender, heredity, and health status (120). According to a meta-analytic review (22),
youth (11-13 years olds) are trainable on this parameter. To study cardiorespiratory
training effects longitudinal data are clearly preferential on scientific literature (22).
Additionally, research increasingly indicates that resistance training, in addition to aerobic
activities, can offer unique benefits for children and adolescents when appropriately
prescribed and supervised (2,9,133). In school context, children and adolescents involved in
physical education classes often perform strength and endurance training concurrently in an
effort to achieve specific adaptations to both forms of training (42,56,80,107), nevertheless
scientific literature has produced inconclusive results.
Periods of training cessation can produce a positive delay transformation rebound in
physical fitness performance (47), which is determinant on school performance evaluation
Object of study
10
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
of the student. The extent of performance decrease may depend on the length of the period
recess in addition to training levels and performance attained by the subjects (78).
Aerobic fitness
Aerobic fitness is defined as the overall capacity to supply energy to the working muscles in
order to support sustained physical activity and the ability to carry out prolonged strenuous
exercise (93). This parameter is also referred as cardiorespiratory capacity (93), aerobic
capacity (22), aerobic power (141), cardiovascular fitness (93), endurance fitness or
maximal aerobic power (93). Aerobic fitness determines performance in a wide range of
activities, and in a performance context (8,134), and aims to increase maximal oxygen
uptake (VO2max) or other indices of aerobic fitness such as lactate/ventilatory threshold or
exercise efficiency (8). VO2max is the most commonly used parameter to investigate the
functional state of the oxygen transport system (8) and has long since been considered by
the World Health Organization as the single best indicator of cardiorespiratory fitness (108).
As mentioned, youth (11-13 yrs) are indeed trainable, but the extent of the training response
may be somewhat lower than their adult counterparts (68). It appears that pubertal status
plays the most significant role in determining the effects of training on VO2max, but there is
insufficient evidence to determine the effects of the training stimulus, particularly due to the
lack of properly documented exercise intensities in past research (68). The critical stage of
maturity where training may exert its greatest impact remains speculative; therefore there
is a need for additional inquiry to elucidate this perplexing question (68).
Muscular strength
Another component of physical fitness, muscular strength, by definition refers to the
maximal force or tension that a muscle or a group of muscles can generate at a specified
Object of study
11
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
velocity (60,93). Resistance training refers to a specialized method of conditioning, which
involves the progressive use of a wide range of resistive loads and a variety of training
modalities designed to enhance health, fitness, and sports performance (40). Although the
term resistance training, strength training, and weight training are sometimes used
synonymously, the term resistance training encompasses a broader range of training
modalities and a wide variety of training goals (40). The term weightlifting refers to a
competitive sport that involves the performance of the snatch and clean and jerk lifts (40).
Scientific evidence states that strength training should be part of a comprehensive health
maintenance (33,40) and physical performance (33,40) effective strategy for youth, as long
as it is carefully prescribed and monitored (32,40,59,86,5,33,56,106,111). Comprehensive
school-based programs are specifically designed to enhance health-related components of
physical fitness, which include muscular strength (89,128). However, strength school-based
programs aiming an increase in physical fitness performance are scarcely studied and with
inconclusive findings.
Concurrent strength and aerobic training
Concurrent resistance and aerobic training refers to stimulate both strength and aerobic
development on the same training session. On this issue, the scientific literature has
produced inconclusive results. Some studies have shown that concurrent training impairs
the development of muscular strength and power but does not affect the development of
aerobic condition when compared with both form of stand-alone training. Some researchers
have reported that concurrent training has an inhibitory effect on the development of
strength and endurance (42,47,56). For example, the addition of heavy resistance training to
specific team handball training skills in adolescents’ boys resulted in gains in maximal
strength and throwing velocity, but it may have compromised gains in the production of
Object of study
12
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
explosive force in the leg and endurance running (50). Yet, the precise mechanisms that
underlie the observed impairments in training adaptation during concurrent training have
to be identified (78,80,124).
Differently, in adults, concurrent training produce better strength and aerobic fitness results
rather than if each, strength or aerobic training methods are performed separately (18). In
this line, physical education classes demands a balance between strength and aerobic
capacity, and it seems important to training concurrently both capacities. Nevertheless, the
effects of concurrent strength and aerobic training in elementary school untrained students
have yet to be investigated.
Another important concern of this thesis is related to training effects in young schooled girls,
since less research has been centered in female subjects. Female participation in sport has
increased dramatically over the previous 20 years in a variety of events. However, despite
the increase in female physical activity (PA) regular programs, there is a paucity of research
on performance characteristics of female adolescents and to the authors’ knowledge few
data are available for young schooled girls (37,115). Schoolgirls have been described as less
active than their male age-peers (35,90) and become even less physically active as they are
going through adolescence (35,115). In addition, less physically active children tend to
remain less active than the majority of their peers during early adolescence (75,118).
Nevertheless, it was reported by several studies that physical activity levels of children aged
13 to 15 years old are positively related with physical fitness (75). Fortunately, there is
strong evidence that school-based interventions are effective to promote PA levels
(34,114,115) and, therefore, school seems to provide an excellent setting to enhance its
levels (135) by implementing physical fitness programs.
Object of study
13
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Detraining effects
The principle of training reversibility states that whereas regular physical training results in
numerous physiological adaptations that enhance physical and athletic performance,
stopping or markedly reducing training induces a partial or complete reversal of these
adaptations, compromising performance levels. Therefore, the reversibility principle can be
considered the principle of detraining (51).
Detraining is defined as the partial or complete loss of training-induced anatomical,
physiological and performance adaptations, as a consequence of training reduction or
cessation (85). Training cessation implies a temporary discontinuation or complete
abandonment of a systematic programme of physical conditioning (85). Reduced training is
a non-progressive standardised reduction in the quantity of training (84), which may result
in a maintenance or even in an improvement of many of the positive physiological and
performance adaptations acquired with training process (84,53).
Interruptions in training process because of illness, injury, holidays, post-season break or
other factors are normal situations in numerous kind of sport (41,36,40) and in school
context as well. The extent of performance level decrease may depend upon the length of the
period recess in addition to training levels and performance attained by the subjects (78).
Nevertheless, information about the changes in resistance training-induced strength gains
during detraining in pre adolescents is still scarce (117) and insufficient studies (10,41)
have investigated the effects of detraining with an inclusion of a control group to control for
growth-related rises in muscular strength. This is important since the period of strength
training cessation can produce a positive delay transformation rebound in sports specific
performance (47), which is determinant on school performance evaluation of the student.
Object of study
14
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Summary
Performance related physical fitness studies reflects (i) the insufficient evidences to
determine the effects of the training stimulus over endurance development, particularly due
to the lack of properly documented exercise intensities in past research, (ii) that strength
school-based programs aiming at an increase in physical fitness performance are scarcely
studied and with inconclusive findings, (iii) that effects of concurrent strength and aerobic
training in elementary school untrained students have yet to be investigated, and that
scientific literature has produced inconclusive results on this issue, (iv) information about
the changes in resistance training-induced strength gains during detraining in pre
adolescents is still scarce and an insufficient number of studies have investigated the effects
of detraining with an inclusion of a control group to control for growth-related rises in
muscular strength, and at last (v) this kind of studies in school girls are even uncommon
than in boys.
Problems, goals, and hypotheses
15
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
General goals
This thesis aimed to: (i) study the effects of strength training (strength training alone), and
the effects of concurrent strength and aerobic training on body composition and
performance variables of untrained adolescent subjects as result of a school-based program;
(ii) study the effects of detraining period on body composition and performance variables of
subjects which trained only strength and of subjects which trained concurrently strength
and aerobic capacity.
Research problems
Scientific literature analysis accomplished shows that there are several empirical
problematic questions, which justify the definition of one or more problems. We can define
the follow concerns:
(i) There is insufficient evidence to determine the effects of the training stimulus,
particularly due to the lack of properly documented exercise intensities in past
research. Strength school-based programs aiming at an increase in physical fitness
performance are scarcely studied and inconclusive findings exist.
(ii) Different studies on children have reported no significant strength and power
increases after the intervention period of strength training programme.
Nevertheless, other studies have shown that strength and power gains are possible.
(iii) Concurrent training promotes benefits on both strength/power and aerobic
development. However, in sports sciences literature contradictory results were
found regarding possible impairments due to concurrent training.
Problems, goals, and hypotheses
16
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
(iv) Conclusions about the changes in resistance training-induced strength gains during
detraining in pre adolescents are still scarce, inconsistent and insufficient studies
have investigated properly the effects of detraining on non-trained subject’s physical
fitness performance.
To explain the effects of strength training process performed alone or concurrently to
aerobic training and to explain the detraining phenomena we defined the follows questions,
which led us throughout this research:
1) Is strength training really effective in non-active adolescent subjects?
2) When trained alone, does strength training produce substantial higher muscular
strength and body composition improvements than training concurrently to
endurance?
3) Does concurrent resistance and endurance training impair endurance improvements?
4) Is it possible to observe similar results in both genders, regarding concurrent training
and detraining periods?
5) Are twelve weeks of detraining period sufficient to lose all training improvements
resulting from the training program?
Studies’ specific goals
Arising from main empirical stone marks and problems, specific goals were:
1) To analyze and synthesize information published in English language and that
fulfilled the following criteria: (i) experimental studies in children or adolescents
samples (aged 10-18 years old); (ii) at least one exercise intervention investigated
endurance, resistance training, either in isolation or as an adjunct to an alternative
treatment (Study number 1: review);
Problems, goals, and hypotheses
17
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
2) To study the effects of a school-based resistance training program (performed
alone) and the effects of a school-based concurrent strength and aerobic training on
body composition and performance variables of untrained boys (Study number 2);
3) To study the effects of a school-based strength training program (performed alone)
and the effects of a school-based concurrent strength and aerobic training on body
composition and performance variables of untrained girls (Study number 3);
4) To study the effects of a detraining period on body composition and performance
variables of boys, which trained only strength and of boys which trained
concurrently strength and aerobic training (Study number 4);
5) To study the effects of a detraining period on body composition and performance
variables of girls, which trained only strength, and of girls which trained
concurrently strength and aerobic training (Study number 5).
Hypotheses
The following hypotheses were defined:
Hypothesis 1 – School-based strength training is really effective on non-active
adolescent subjects for both genders.
Hypothesis 2 - When trained alone, strength training does not produce significant
higher muscular strength increases in boys when compared with results obtained
after concurrent strength and aerobic training.
Hypothesis 3 - When trained alone, strength training does not produce significant
higher muscular strength increases in girls when compared with results obtained
after concurrent strength and aerobic training.
Problems, goals, and hypotheses
18
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Hypothesis 4 - When trained alone, strength training does not produce significant
higher body composition improvements in boys when compared with results
obtained after concurrent resistance and aerobic training.
Hypothesis 5 - When trained alone, strength training does not produce significant
higher body composition improvements in girls when compared with results
obtained after concurrent strength and aerobic training.
Hypothesis 6 - Concurrent resistance and aerobic training does not impair aerobic
improvements in boys.
Hypothesis 7 - Concurrent strength and aerobic training does not impair aerobic
improvements in girls.
Hypothesis 8 - Regarding concurrent training it is possible to observe significant
improvements in both genders, and regarding to detraining both genders would
keep improvements previously acquired during training process.
Hypothesis 9 - Twelve weeks of detraining summer period are not sufficient to
induce significant losses in strength and aerobic parameters in adolescent's boys.
Hypothesis 10 - Twelve weeks of detraining summer period are not sufficient to
induce significant losses in strength and aerobic parameters in adolescent's girls.
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
19
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Study One: Concurrent strength and aerobic training and detraining
programs: effects on adolescents’ physical fitness performance. Study
review.
Regular physical activity during childhood and adolescence is associated with
improvements in numerous physiological and psychological variables and it has been
extensively documented in health related outcomes field (101,102,120,121).
Recommendation for the amount of physical activity deemed appropriate to yield
beneficial health and behavioural outcomes for school-age youth have been also widely
proposed (101,114,120).
In this study, we focused our article review on aerobic and muscular fitness, and on two
physical fitness components (57). We present below main results and conclusions of
studies which have studied cardiorespiratory fitness alone, main results and conclusions
of studies which have studied resistance strength alone. Afterward we present main
results and conclusions of studies which have studied the effects of concurrent resistance
and endurance training program. At last, we summarize the main conclusions of studies
which have investigated detraining effects on non-adults.
Cardiorespiratory fitness is defined as the overall capacity of the cardiovascular and
respiratory systems and the ability to carry out prolonged strenuous exercise (93).
Cardiorespiratory fitness is also referred as cardiorespiratory capacity (93), aerobic
capacity (22) aerobic power, cardiovascular fitness (93), endurance fitness or maximal
aerobic power (93), and is largely determined by habitual physical activity (22,120).
However, other factors influence cardiorespiratory fitness, including age, gender, heredity,
and medical status (120). According to a meta-analytic review (68), youth (11-13 yrs) are
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
20
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
indeed trainable, but that the extent of the training response may be somewhat lower than
their adult counterparts. It appears that pubertal status plays the most significant role in
determining the effects of training on VO2max, but there is insufficient evidence to
determine the effects of the training stimulus, particularly due to the lack of properly
documented exercise intensities in past research (68). Furthermore, longitudinal data are
clearly preferential, particularly in studies examining the effects of training as a function of
pubertal status (68). The critical stage of maturity where training may exert its greatest
impact remains speculative; thus, there is a need for additional inquiry to elucidate this
perplexing question (68).
By definition, muscular strength refers to the maximal force or tension a muscle or a group
of muscles can generate at a specified velocity (60,93). Resistance training refers to a
specialized method of conditioning, which involves the progressive use of a wide range of
resistive loads and a variety of training modalities designed to enhance health, fitness, and
sports performance (40). Although the term resistance training, strength training, and
weight training are sometimes used synonymously, the term resistance training
encompasses a broader range of training modalities and a wider variety of training goals
(40). The term weightlifting refers to a competitive sport that involves the performance of
the snatch and clean and jerk lifts (40).
It’s largely documented that in addition to aerobic activities, research increasingly
indicates that resistance training can offer unique benefits for children and adolescents
when appropriately prescribed and supervised (2,9,133).
Comprehensive school-based programs are specifically designed to enhance health-related
components of physical fitness, which include muscular strength (89,128). However,
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
21
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
resistance school-based programs aiming an increase in physical fitness performance are
less studied and with inconclusive findings.
Therefore, the purpose of this research was to systematically review the effects of
endurance training alone, resistance training alone, concurrent resistance and endurance
training over physical performance of 10 to 18 years old children and adolescents to
assess current knowledge and level of evidence according to the Consolidated Standards of
Reporting Trials (CONSORT) checklist guidelines (82).
Methods
Inclusion and exclusion criteria
Researches that were published in English language and fulfilled the following criteria
were included in this review: (i) experimental studies in children or adolescents samples
(aged 10-18 years old); (ii) at least one exercise intervention investigated endurance,
resistance training (using machines, free weights, elastic bands or tubes, medicine ball,
body weight or a combination of several), either in isolation or as an adjunct to an
alternative treatment.
Search methodology
A systematic database search for full-length manuscripts were performed on Sportdiscus,
Springerlink, Taylor & Francis, Sciencedirect, Wiley interscience, and Pubmed for the
1980–2011 (September, week 4) period.
First, five keyword categorical searches were conducted: (i) ‘resistance training’, or
‘strength training’, or ‘weight training’; (ii) ‘child’, or ‘adolescent’, or pediatric; or
‘paediatric’ (iii) ‘endurance’, or ‘aerobic’, or ‘cardiorespiratory’, or ‘cardiovascular’,
‘VO2max’, or ‘maximal aerobic power’; (iv) ‘concurrent’ and (v) ‘detraining’, ‘recess’. The
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
22
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
reference lists of each of these studies and a number of review papers and position stands
were manually searched to extract further studies.
Cardiorespiratory fitness training
Aerobic fitness determines performance in a wide range of activities, and in a performance
context (8,134), aims to increase maximal oxygen uptake (VO2max) or other indices of
aerobic fitness such as lactate/ventilatory threshold or exercise efficiency (8).
The VO2max is the most commonly used parameter to investigate the functional state of
the oxygen transport system (8) and has long since been considered by the World Health
Organization as the single best indicator of cardiorespiratory fitness (108).
Age and growth effects
It has been hypothesised that maturational factor may determine a child’s potential for
physiologic alterations to occur consequent to physical training (48). Thus, although young
boys will respond to appropriate training programmes with increases in VO2peak, the size of
the changes may be less than those expected in older youths and adults (6,95).
Data on the aerobic training responses of pre-pubertal are sparse, and most studies have
not assessed maturation or monitored carefully the training modality, especially the
intensity of exercise (131).
In a follow up study with a school boy’s untrained sample, Kobayashi et al (61) found that
aerobic power increased from 45.0 to 52.2 (ml.kg-1.min-1) between the ages of 13 and 17.
Therefore, beginning approximately one year prior to the age of peak height growth
velocity and thereafter, training effectively increased aerobic power above the normal
increase attributable to age and growth. After that, another school-based follow up study
(81) also using a untrained school boy’s sample, concluded that activity before
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
23
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
adolescence causes no significant increase in VO2max, but that adolescence is the critical
period during which consistently higher rates of increase in the VO2max of active boys
result in a significantly greater adult value. In another follow up study, Kemper &
Verschuur (58) controlling for chronological age observed that VO2max increases in boys
from 2.4(l.min-1) at age 12+ to 3.8 (l.min-1) at age 17+. Girls’ increase is smaller, from
2.31/min to 2.71/min over the same age range. When VO2max is aligned on peak height
velocity, their results show that the peak increase coincides roughly with the age at peak
height velocity. It demonstrates that in general no discrepancy between structural and
functional growth occurs in boys and girls during their teens as far as VO2max is
concerned. Concordantly, LeMura et al. (68) in an analytic review concluded that children
(both genders) are indeed trainable, but the changes in VO2max are modest and are
significantly impacted by the Experimental approach of the investigation, the age of the
children, and the nature of training stimulus.
Wennlöf et al. (130) also reported in a cross-sectional study a better aerobic fitness of
post-pubertal boys and girls compared with their pre-pubertal peers. Others suggest that
cardiovascular training will rebound as minimal changes to peak or submaximal aerobic
function in young girls (129) and boys (131). Contrarily, Obert et al. (92) highlights the
effectiveness of an aerobic training programme to improve the maximal power during
short-term exercise in pre-pubertal male and female children. Another longitudinal study
(76) shows that VO2max can increase in pre-pubertal children after an aerobic training
programme and that such an increase is of the same extent in both genders when the
initial aerobic fitness is taken into account. Similarly, more recently, McNarry et al. (79)
challenged the notion that differences in training status in non-adult people are only
discernible once a maturational threshold has been exceeded. In same year, another study
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
24
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
(64), using a sample of 162 boys (aged 13–14 years) at various puberty stages, found that
adolescents aged 13–14 years with moderate rates of development are characterized by
higher indices of power and capacity of the aerobic energy supply system as compared to
adolescents with accelerated maturation. This group of adolescents has also been
observed to exhibit a lower maximal aerobic power against a background of higher
capacity and efficiency of the aerobic system functioning as compared to adolescents with
slow maturation. The groups of adolescents with moderate rates of maturation have been
shown to exceed schoolboys groups with accelerated or slow development with respect to
the power of mixed aerobic–anaerobic work. Boys aged 13–14 years with accelerated
development have been found to differ from schoolboys with moderate or slow
maturation by high anaerobic capacity, relatively low aerobic capacities and an increase in
the tone of the parasympathetic nervous system.
Onset physical fitness level effect
The first studies found a remarkable increase in aerobic power was observed in trained
boys compared with their non-trained peers (61,81). However, that marked increasing
was conditioned to peak height growth velocity occurrence (61,81). In a Physical
Education-based study (98) it was found that despite VO2max improvements were
independent either of initial VO2max level and initial enrolment on sports teams, it was not
from a level of habitual physical activity. In this line, Welsman et al. (129) did not find any
change in VO2peak in a pre-pubescent girl’s sample with low levels of physical activity, after
a training period of both modes aerobics and cycle ergometer. Using a sample of 16-18
year old elite handball players and untrained boys, Łuszczyk et al. (74) observed adapting
changes in the circulatory system in young handball players. The group practicing
handball showed a significant higher value of O2.HR-1 comparing with the untrained boys.
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
25
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Oxygen deficit was higher in the trained group, but no statistically significant differences
between both groups were observed. In a recent cross-sectional study (79) it was found
that pre-pubertal, pubertal and post-pubertal girls had a higher VO2peak during cycle and an
upper body ergometer tests. In the same study it was also observed that trained girls also
had a higher peak cardiac output during both cycle and an upper body ergometer tests,
and this reached significance in pubertal and post-pubertal girls, compared with untrained
girls.
Gender effects
In a 4 years follow up study, Kemper & Verschuur (58) found that when considered the
absolute value of VO2max (l.min-1) boys increased from 2.4 l.min-1 at age equal or more
than 12 year olds to 3.8 l.min-1 at age equal or more than 17 year olds. That increase in
girls is minor (from 2.3 l.min-1 to 2.7 l.min-1, respectively) compared with their male peers.
However, when body weight was taken in account VO2max (l.min-1.kg-1) and considering
the same age range, boys remained constant (59 l.min-1.kg-1) and in girls it gradually
decreased from 50 to 45 (ml.min-1.kg-1). Girls’ results are partly justified by an increase in
body fat that the authors have found in female sample. Wennlöf et al (130) also found in
the 15 to 16-yrs old group that boys had significant higher absolute (+.96 l.min-1) and
relative (+11.0 ml.min-1.kg-1) estimated VO2 peak values than the girls. In 9-10 yrs-old boys
and girls group it was noticed in absolute (+.18 l.min-1) and relative (+5.3 ml.min-1.kg-1)
estimated VO2, significant higher scores in boys than girls (130). Similarly, after a 13-Week
Aerobic Training Programme it was observed in a 10-11 yrs old sample that boys
increased their VO2max to a greater extent than the girls with a concomitant higher
maximal stroke volume improvement (91). No alterations were observed in the stroke
volume pattern from rest to maximal exercise, indicating that the increase in stroke
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
26
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
volume rest was determinant in the improvement of maximal stroke volume and thus in
VO2max values (91). However, Rowland & Boyajian (98) in an experimental study
(physical education-based endurance training program, using a 10.9-12.8 yrs old sample)
observed that training improvements in VO2max were no different in boys and girls.
Different results were achieved by Mandigout et al. (76). The authors found that 10–11yr
old girls significantly increased VO2max after the training programme and that increase
was significant higher in comparison with boys.
Program design
In paediatric population with equal or more than 10 years old, few studies have
investigated the variables that optimize endurance program. Some experimental studies
have examined the efficacy of school-based interventions (22,102), others have studied the
influence of age/maturation status (58,131), gender (22,58,76,91,130) or initial physical
fitness (22,98) over cardiorespiratory fitness but an exiguous number of experimental
studies has properly investigated load components such as mode, frequency, session
duration or intensity. Ewart, et al. (26) evaluated the effects of aerobic exercise physical
education on blood pressure in high-risk adolescent girls and compared with traditional
physical education classes. Nevertheless, the main aim of that study was not to optimize
the endurance training design and consequently the validity of their results is limited on
this context. Bogdanis et al. (12) evaluated and compared the effectiveness of two different
off-season 4 week-basketball training programs on physical and technical abilities of
young basketball players. The authors (12) have concluded that VO2max similarly
improved after specialized basketball and mixed basketball plus conditioning training
program.
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
27
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Experimental studies have been using different modes such as interval and continuous
long-distance running (76,91,92), aerobics class (26,129), handball (74), indoor and
outdoor aerobic games (98), basketball (12,98) or cycling (129,131). Regarding frequency,
it has been used two (26,92,96), three (76,91,98,129,131) and five (12) days per week.
One single study used programmes of 4 weeks (12), other two, 8 weeks (129,131), three
studies used programs of 13 weeks (76,91,92), one has used 12 weeks (98), other used 16
weeks (96) and another one has used 18 weeks (26). Only one study (74) had a larger
duration (2 years), however, training protocol was not described. Session durations vary
from 20 to 30 minutes (96,98,131), 50 minutes (26) until more than 1 hour (12,76,91,92).
Concerning training intensity, values above 80% Heart Rate Maximum (12,76,91,131)
have been used. Three studies defined a Heart Rate target range from 160 to 170 beats per
minute for a sample of 10.9-12.8 yrs old boys and girls (98), for a sample of 9-10 yrs old
girls (129) and for a sample of 10 yrs old boys (131). Defining a common and unbending
target range for every subject with different characteristics and different physical fitness
level, the stimulus would be not appropriate and thus create a bias on data.
In conclusion, it is difficult to compare studies when different modes, intensities, durations
(session and program) and objectives are used. Nevertheless, in all cited studies, except
one (129), it was found that a training program led to a rise in VO2max. Thus, more studies
are needed to clarify what is the best methodology on endurance training in paediatric
population.
Strength training
Recent findings indicate that resistance training can offer unique benefits for children and
adolescents when appropriately prescribed and supervised (32,40,86,133). Indeed,
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
28
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
improvements in muscular fitness and speed/agility, rather than cardiorespiratory fitness,
seem to have a positive effect on skeletal health (93).
Strength training (also called resistance training) refers to a specialized method of
physical fitness conditioning that comprises the progressive use of a wide variety of
resistive loads — from medicine balls to high intensity plyometric drills — that enhance or
maintain muscular fitness (3,4,15,31,32,36,40,86). Research into the effects of resistance
exercise on youth has increased over the past years (4,15,31,36). Consequently, youth
strength training is, nowadays, accepted by medical and fitness organizations and this
qualified acceptance is becoming universal (3,4,15,31). Complementary, school physical
education is the primary societal institution with the responsibility for promoting physical
activity in youth (22,102) and comprehensive school-based programs, are specifically
designed to enhance among other fitness components, muscular strength (36,40).
Several factors seem to have an effect over muscular strength development and studies
have been used different methodologies and thus different results.
Age/growth effects
The efficacy and success of a resistance training program on children has been questioned
in the past (71). Children lack adequate circulating androgens required for gains in
muscular strength was appointed as an explanation for that ineffectiveness (67). Thus,
different studies on children have reported no significant strength increases after the
intervention period of strength training programme (23). A great range of reasons such as
no inclusion of control group, testing methods different from training drills, inadequate
load (resistance, repetitions, or sets), or a short study period can explain the lack of
significant strength gains reported in those studies (71). Nevertheless, numerous other
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
29
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
studies comparing strength trained children with age and sex matched controls have
shown strength gains are possible (94) with no detrimental effect on growth (87,99).
Faigenbaum et al. (44) found for both genders and pre-pubescent population that
twice/week strength training programme can increase significantly (p<.001) strength in
upper and lower limbs strength [10-RM leg extension (64.5%), leg curl (77.6%), chest
press (64.1%), overhead press (87.0%), and biceps curl (78.1%)] after strength training
program whereas gains in the control group averaged 13.0% (range 12.2 to 14.1%) for the
same tested motions. The mean gains in strength for the experimental group were
significantly greater than those for the control group. In vertical jump and seated ball put,
subjects submitted to training programme improved 13.8% and 4% respectively,
compared with 7.7% and 3.9% observed in control group. There were no significant
interaction effects on vertical jump and seated ball put; however, significant (p<.05) main
effects (both groups combined) for time were found on both performance measures (44).
Concordantly, Ozmun et al. (94) for the pre-pubescent boys and girls that significant
isotonic (22.6%), and isokinetic (27.8%) strength gains and integrated EMG amplitude
(16.8%) increases were found after training programme period without corresponding
changes in arm circumference or skinfolds. For the authors (94) early gains in muscular
strength resulting from resistance training by prepubescent children may be attributed to
increased muscle activation.
The effectiveness of a strength training program in pre-pubescent boys and girls was
confirmed using 6RM leg extension strength and 6RM chest press strength tests since
exercise group significant increased +53.5 and 41.1%, respectively, compared with non-
significant increase of 6.4 and 9.5% in controls (41). Significantly greater gains in strength
during the 2nd phase of training for 6RM leg extension and 6RM chest press strength tests
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
30
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
has been found, comparing with controls (41). After a training program of 1RM chest-
press exercise for either low or high repetitions maximum, it has been found that
prepubescent boys are sensitive to gains in 1RM chest-press test (38). That increase was
about 52% for low repetitions maximum and 66% for high repetitions maximum, of their
initial 1 RM (38). More recently the positive effect of a strength training program over
strength variables was confirmed in school context for pre-pubescent population (19).
This issue was specifically studied in a stone mark study (71) which investigated the
efficacy of strength training in prepubescent to early post-pubescent males and females.
Prepubescent to early post-pubescent boys and girls who participate in a 12 week strength
training programme can significantly gain 10RM strength; increase upper and lower
extremities girths measures, while decreasing skinfold thickness, increase performance in
selected motor tasks (flexed arm hang, jump & reach, shuttle run, standing long jump, 30
yard dash) and enhance flexibility (71). In the same study, no significant differences in 10
RM strength gains were noted between the Tanner stage 1-2 and 3-5 groups. It also was
found that the predominant main effect on motor performance was treatment. For the
most part, regardless of Tanner’s stage and gender, strength training groups experienced
greater improvements in motor performance than control groups.
Beyond the fact that pre-pubescent subjects are respondents to strength training program,
it was demonstrated that after a plyometric training program prepubescent soccer players
boys can increase performance in muscle power tests such as maximal cycling power
(p<.01), CMJ (p<.01), squat jump (p<.05), multiple 5 bounds (p<.01), repeated rebound
jump for 15 seconds (p<.01) and running velocity on 20m (p<.05), performances increased
in the treatment group without concomitant increase in controls (21). More recently, it has
been found that in trained (55) and untrained (62) pre- (55,62) and early pubertal boys
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
31
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
(55), upper and lower body complex training (combination of dynamic constant external
resistance and plyometric drills) is a time-effective training modality that confers
improvements in anaerobic power and jumping, throwing and sprinting performance, and
marked improvements in dynamic strength (55,62,104).
In pre-pubertal obese children it was demonstrated that an exercise programme with
emphasis on strength training can result in significant beneficial effects on lean mass
(133), bone mineral accretion (133), per cent and total fat mass (104). The reduction of fat
mass was concomitant with significant improvements observed in static jump power,
which improved by 10.5% at week 16 in the group which trained for 24 weeks (104).
The effectiveness of strength training in pre-pubescent subjects can be reached with
different training program context such as sports-based (21,47), fitness club-based
(41,38,55,71,133) or school based (19,36,62) and resistance modes such as child sized
weight machines (41,38,44), free weights or common weight machines (47,71), body
weight/tubing exercises/dumbbell exercises (19,47,104) and medicine ball
(19,36,47,104).
Strength training is also effective in pubescent as well as in post-pubescent population. In
a pubescent male athletes sample, upper (bench press) and lower [leg press (20,52) and
vertical jump (52)] strength has been increased after training period (20,52). Tsolakis et
al. (117) found that resistance training induced strength changes independent of the
changes in the anabolic and androgenic activity.
A considerable number of studies have investigated the effect of strength training on
adolescents. After a training period subjects significantly increase predicted 1RM squat
(92%) and 1RM bench press (20%), right (10.39cm) and left (8.53cm) single-leg hop
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
32
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
distance and vertical jump (3.3cm) and speed in a 9.1-m sprint (0.07seconds) (87). Basic
strength training alone induced favourable neuromuscular and biomechanical movement
changes (87,69) providing greater sport-specific training improvements (116) in high
school male (87,116) and female (69) athletes. Thus, the plyometric program may further
be utilised to improve muscular activation patterns (87,69). When a resistance training
program was used in addition to soccer training on the physical capacities of male
adolescents it resulted in significant (p<.05) higher 1RM bench press and 1RM leg press,
squat jump and CMJ height, and 30-m speed performance (17). Contrarily, Bogdanis et al.
(12) found that a specialized basketball training program, performed exclusively on-court
was as effective as a basketball plus strength training program in terms of aerobic and
anaerobic fitness improvement (12): trunk muscle endurance was equally increased for
both groups but arms endurance was improved significantly more after basketball plus
strength training program (50±11%) compared to specialized basketball training program
(11±14%, p<.05).
Overweight adolescent males, after strength training period, can significantly increase
performance in 1RM bench press and 1RM leg press while the body fat percentage (105)
also significantly decreased. This finding was confirmed recently for normal weight
untrained boys and girls (73): after either a free weight or elastic tubing training program,
improvements were observed on their body composition concomitant with increases in
performance of upper and lower body muscular strength.
A short bout of 10 to 15 minutes in each physical education class, is sufficient to achieve
significant gains in the shuttle run, long jump, sit and reach flexibility, medicine ball
abdominal curl, medicine ball push up and medicine ball toss (36). The introduction of
manual resistance training on physical education class also resulted in curl-up test (24).
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
33
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
The addition of plyometric training to a resistance training program may be more
beneficial than resistance training and static stretching for enhancing selected measures of
upper and lower body power in boys. Faigenbaum et al. (35) has demonstrated that
subjects who performed a plyometric training in addition to resistance training program
made significantly (p<.05) greater improvements than subjects who performed resistance
training only in long jump (10.8cm vs. 2.2cm), medicine ball toss (39.1cm vs. 17.7cm) and
pro agility shuttle run time (-0.23sec vs. -0.02sec) following training.
An important finding highlight that performing resistance training at a moderate volume is
more effective and efficient than performing at a higher volume (48): junior experienced
lifters can optimize performance by exercising with only 85% or less of the maximal
volume that they can tolerate.
Onset physical fitness level effect
It’s well documented that resistance training is effective on muscular strength
development of either untrained (19,35,36,38,39,43,44,55,62,71,73,94,104,105,117,133)
or trained (12,17,20,21,36,47,69,86,116) pre-pubertal (21,31, 39,43,44,62,71,94,104,133)
or pubertal/post-pubertal non-adult population (12,17,20,24,35,36,55,69, 86,105,117).
Muscular strength can be improved during childhood years, and favour a training
frequency a twice/week (39), 1 set/exercise of a higher repetition maximum (15-20 reps.)
training range (38) for untrained children participating in an introductory strength
training program (39). Similarly, comparing with untrained subjects, highly experience (at
least 6 years) adolescent athletes in different sports (basketball, soccer, and volleyball
players) girls, significantly increase predicted 1RM squat and 1RM bench press
performances, as well as right and left single-leg hop distance, vertical jump and speed 9.1-
m running performances; rise movement biomechanics: increase knee flexion-extension
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
34
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
range of motion during the landing phase of a vertical jump and decreased knee valgus and
varus torques (86). Another research has specifically investigated the effect of sports
experience on strength training adaptation in adolescent males (52): comparing with
controls, experienced training subjects and novice training subjects significantly increased
leg press, bench press and vertical jump after a 12 weeks, thrice a week, with free weights
and machines.
Gender effects
Faigenbaum et al. (41,38,39,43,104), Faigenbaum and Mediate (36), Lubans et al. (73) and
Yu et al. (133) observed increases in various training-induced strength gains in
prepubescent (41,38,39,43,104,133) and pubescent (36,73) boys and girls; however,
details of the detraining responses were not reported in those studies.
Cowen et al. (19) found that boys and girls revealed improvements in push up scores, curl
up scores, and overall percentile ranking after a strength training program; however, the
statistical difference between both genders was not reported.
Lillegard et al. (71) observed no significant 3 or 2-way (gender, Tanner’s stage, treatment)
interactions for any of 10 RM strength differences (barbell curl, triceps extension, bench
press, lat pull, leg extension, leg curl) and for any of the 5 motor performance parameters
(flexed arm hang, jump and reach, shuttle run, standing long jump, 30 yard dash).
However, when it was considered the gender main effect, in 2 of the six 10RM strength
measures (lat pull, leg extension), males had significantly gains than females and
significant pre- and post-test genders difference occurred on shuttle run (favoured the
females) (71).
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
35
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Program design
Resistance training programs as short as 10-15 minutes per session (36), in addition to
physical education classes have been showed to be sufficient to promote strength
developments in paediatric population. Different weekly training frequency has used such
as once a week (39,43,133), twice a week (17,31,35,36,38,39,44,47,62,73,105) thrice a
week (20,21,24,52,55,69,71,87,94,104,116,117,133) or five days a week (12,19,48) with
success on strength performances development. Resistance training programs using
experienced non-adults population lasted from 4 (12) to 24 weeks (20). When we focus
our analysis on untrained non-adults subjects studies, we found that the mostly used
period was 8 weeks (41,38,39,43,44,73,117). Training period range has lasted from 6
(35,36) to 64 (36+28) weeks (133). However, significant gains in upper and lower limbs
strength can occur during a short period as the first 4-weeks of a training program (41).
Training Frequency
Faigenbaum et al. (39) studied the effects of week frequency (1 vs. 2 sessions/wk) of
strength training on upper and lower body strength in non-prior strength training
experienced children. The 1-day group training at a 62.3 and 68.8% intensity (of their
initial 1RM) on the chest press and leg press exercises, respectively, whereas the 2-day
group trained at an intensity of 61.1 and 67.4% (of their initial 1RM), respectively (39).
The authors found that in 1RM chest press strength performance, participants who trained
1 day/week increased 9.0% from their initial score whereas 2 days/week strength training
group increased 11.5% [only this group made significantly (p<.05) greater gains in this
variable as compared to the control group]. Compared with baseline scores, 1 day/week
training group increased 14.2% in 1RM leg press strength whereas 2 days/week strength
training group increased 24.9% (39). The control group has increased 4.4 and 2.4% in first
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
36
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
and second variable, respectively (39). The authors proposed that the control group’s
strength gains may be explained by growth, maturation, and the learning effect. Despite no
pre-post program significant differences between groups were observed in handgrip
strength, long jump, vertical jump, and flexibility it can be assumed that muscular strength
can be improved during childhood years, favouring a training frequency of twice/week for
children participating in an introductory strength training program. These results have to
be taken with caution as long as throughout the study period 64% of subjects in the 1-day
group, 70% in the 2-day group, and 69% in the control group regularly participated (at
least 2-day/week) in organized community sports programs (mainly swimming and
soccer) and these last programmes were not controlled by researchers.
Other authors (20) have studied the effect of training week frequency (1 vs. 2
sessions/wk) in 12 wks in-season over strength gains retaining. Firstly, all subjects
(including control group) attended a preseason 12 wks, thrice a week of progressive
strength training. In in-season, significant differences (p<.05) in absolute strength scores
between group which trained 2 day/wk and the control group prior to the maintenance
protocol for bench press were observed. At the end of the 12-week in-season period,
subjects of both weekly training frequencies (1 and 2 sessions/wk) differed significantly
(p<.05) from the control group in absolute bench press strength scores. Additionally,
significant differences (in pre- to post in-season program) between 1 and 2
sessions/wk training groups and the control group were observed. No other differences
were observed between groups. During the 12- week maintenance protocol, the group
which trained 1 day/wk had significant increases in strength in the bench press (p<.05)
while the control group had significant decreases in the bench press and pull-ups. Thus,
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
37
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
for pubescent male athletes, 1 day/wk maintenance program is sufficient to retain
strength performance during the competitive season.
Training intensity and volume
Trained adolescents of both genders can benefit from a short session of strength training.
A 10 to 15 minutes of medicine ball strength training program performed twice a week on
physical education classes have been shown to be sufficient to significantly (p<.05)
promote gains in long jump, medicine ball abdominal curl, medicine ball push up and
medicine ball toss tests (36).
González-Badillo et al (48) found that junior resistance-trained athletes can optimize
performance by exercising with only 85% or less of the maximal volume that they can
tolerate. In fact, after a periodized routine using the same exercises and relative intensities
but a different total number of sets and repetitions at each relative load, the authors
observed that moderate-volume group showed a significant increase for the snatch, clean
& jerk, and squat exercises (6.1, 3.7, and 4.2%, respectively, p<.01), whereas in the low-
volume group and high-volume group, the increase took place only with the clean & jerk
exercise (3.7 and 3%, respectively, p<.05) and the squat exercise (4.6%, p<.05, and 4.8%,
p<.01, respectively). The increase in the snatch exercise for the moderate-volume group
was significantly higher than in the low-volume group (p=.015). The study’s (48) results
showed higher strength gains in the moderate-volume group than in the high-volume
group or low-volume group. There were no significant differences between the low-
volume group and high-volume group training volume-induced strength gains (48). These
findings are consistent with Faigenbaum et al. (43) conclusions: muscular strength and
muscular endurance can be enhanced in untrained pre-pubertal boys and girls and favour
the prescription of higher repetition–moderate load resistance training programs during
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
38
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
the initial adaptation period”(43). That study’s results shows that in 1RM leg extension
strength a significant increase was observed in both Low-Repetition-High-Load Group
(+31.0%) and High-Repetition-Moderate-Load Group (+40.9%) compared with controls. In
leg extension muscular endurance both Low-Repetition-High-Load Group and High-
Repetition-Moderate-Load Group significantly increased compared with controls, although
gains resulting from High-Repetition-Moderate-Load Group (13.1±6.2 repetitions) were
significantly greater than those resulting from Low-Repetition-High-Load Group (8.7±2.9
repetitions). In chest press 1-RM strength and chest press muscular endurance tests only
the High-Repetition-Moderate-Load Group made gains (16.3% and 5.2±3.6 repetitions,
respectively) than gains in the CG (43). More recently, another study (38) in untrained
children who began resistance training, confirmed this thesis. Study’s results (38) favour
the prescription of a higher RM training range (1 set of 15-20 RM): both Low-Repetition-
Maximum Group and High-Repetition-Maximum Group made significant gains on 1 RM-
strength (21% and 23%, respectively), however, only the High-Repetition-Maximum
Group made significantly greater gains (42%) on 15 RM local muscular endurance test
(38).
Nevertheless future longstanding studies are necessary to evaluate the effects of different
combination of sets and repetitions on performance measures in non-adult (38).
Training mode
Different modes such as medicine balls (19,36,47,104), weighted bags (104), exercise
machines (41,38,39,43,47,48,52,71,133), dumbbells (19,52,73,104) or elastic bands/tubing
(19,73,104) have been used successfully on strength training development of both trained
and untrained or pre- and pubescent boys and girls. We didn’t find any study that has been
specifically compared the effect of different modes on strength training development.
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
39
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Sport-specific training improvements
School-based strength training programs seems to be effective on greater sport-specific
training improvements, even in trained adolescents male. The addition of resistance
training program to soccer training greatly improved maximal strength of the upper and
the lower body (1RM bench press and 1RM leg press, squat jump), vertical jump height,
and 30-m speed, than soccer training alone (17). Conversely, Bogdanis et al. (12) observed
similar improvement magnitude in either specialized basketball training group or mixed
basketball plus conditioning training group on peak and mean anaerobic power and
anaerobic capacity as well as in trunk muscle endurance. Despite that, arms endurance
was improved significantly more in mixed basketball plus conditioning training group
(50±11%) compared to specialized basketball training group (11±14%, p<.05). Because
circuit training was also performed in each session of the mixed basketball plus
conditioning training group, the authors established the duration of the fundamental skills,
individual work, team work and offensive/defensive co-operations among players was 20-
40% shorter in this group comparing with specialized basketball training group. Thus, this
difference can explain the similar improvement magnitude observed in each group at the
end of experimental period. Also the adaptation to initial training plan, which was changed
after athletes have been complained, can explain that similitude. More recently, Szymanski
et al. (116) found that a medicine ball training programme performed additionally to a
stepwise periodized resistance training programme with bat swings provided greater
sport-specific training improvements in torso rotational and sequential hip-torso-arm
rotational strength for high school pubescent male baseball players. Short-term plyometric
training programmes (different plyometric exercises including jumping, hurdling and
skipping) additionally to their soccer training resulted in increased athletic performances
in prepubescent trained boys (21). It appears that, also in an aquatic environment,
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
40
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
strength training can enhance sports performance. Thus, eight weeks of combined dry land
strength and aerobic swimming training in young competitive swimmers suggests that
although cannot be clearly assumed that strength training provides an improvement in
swimming performance, a tendency to progress sprint performance due to strength
training was noticed (47).
Plyometric training effects
Using a combination of dynamic constant external resistance and plyometric drills on pre-
and early pubescent untrained boys, it was concluded that upper and lower body complex
training is a time-effective training mode that confers small improvements in anaerobic
power and jumping, throwing and sprinting performance, and marked improvements in
dynamic strength (55,62,86). Lephart et al. (69) investigated the effects of plyometric and
basic resistance training programs on neuromuscular and biomechanical characteristics in
female athletes and concluded that basic resistance training alone induced favourable
neuromuscular and biomechanical changes in high school female athletes; and plyometric
program may further be utilized to improve muscular activation patterns. These findings
must be taken with caution since study was developed in athlete’s sample and no control
group was used. Faigenbaum et al. (35) specifically compared the effects of combined
plyometric and resistance training or resistance training alone on fitness performance.
Performing plyometric training additionally to a resistance training program may be more
beneficial than resistance training for enhancing upper and lower body power (vertical
jump, long jump, 9.1m sprint, ball toss) in untrained boys.
Concurrent resistance and aerobic training
Adaptations as consequence of training process are highly dependent on the specific type
of training implemented (14,136). Aerobic training generally encompasses exercise
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
41
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
volume of several minutes up to some hours at many exercise intensities, increasing the
ability to sustain repetitive high-intensity, low-resistance exercise with minimal fatigue
accumulation and minimal performance loss (13,88). Strength training encompasses
short-duration activities at high exercise intensities, and increases the capacity to perform
high-intensity, high-resistance exercise of a single or relatively few repetitions, and
throwing events in school or sports field (88,137).
Many researchers have rationalised that concurrent training promotes the benefits of both
strength and aerobic training (1). Nevertheless an inhibition in strength or aerobic
adaptation as a consequence of concurrent training has been reported (125). Sale et al.
(100) observed that concurrent strength and aerobic training applied on different days
produced gains superior to those produced by concurrent training on the same day.
Although the training programs were held otherwise constant, alternate-day training was
more effective in producing maximal leg press strength gains than same-day training. This
suggests that the interference effect may also be true when the overall frequency and/or
volume of training are higher. Briefly, the literature researches do not demonstrate the
universality of the interference effect in strength development when resistance training is
performed concurrently with aerobic training (103).
In the present analysis we did not considered studies which have investigated strength
training concurrently to subject’s sports workouts. The results and conclusion of those
studies were analysed before in this article. Thus we only considered researches which
have been investigated the concurrent resistance and aerobic training in untrained youth.
Concurrent resistance and aerobic training has been demonstrated to be effective even in
short periods of strength training as 10 to 15 minutes for untrained adolescents of both
genders. Assuming that Physical Education is mainly aerobic, subjects who participated in
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
42
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
medicine ball training program during the first 10 - 15 minutes of each Physical Education
class have significantly (p<.05) greater gains in the shuttle run, long jump, sit and reach
flexibility, medicine ball abdominal curl, medicine ball push up and medicine ball toss as
compared to the subjects who participated in Physical Education lessons but not medicine
ball training (36).
Subjects who concurrently trained manual resistance and aerobic training in every
Physical Education class have showed significant improvements in one-mile run (p<.002)
and trunk lift (p<.0001) measures from 0-9 and 9-18 wks compared with subjects who
were evolved in a strength training only program (24). Concurrent training seems to be
effective also in pre-pubescent boys and girls. Cowan and Foster (19) observed significant
improvements in one-mile run push up and curl up scores for both genders after a
concurrent strength and aerobic training period.
Thus we can assume that concurrent strength and aerobic training not only does not
impair strength neither aerobic development as seems to be an effective, well-rounded
exercise program that can be used as a means to improve initial or general strength in
youth.
Detraining effects
Interruptions in a training process because of illness, injury, holidays, post-season break
or other factors are normal situations in numerous kinds of sport (41,36,40) and in school
context as well. The extent of performance decrease may depend upon the length of the
period recess in addition to training levels and performance attained by the subjects (78).
Nevertheless, information about the changes in strength training-induced strength gains
during detraining in pre adolescents it is still scarce (117) and insufficient studies (10,41)
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
43
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
have investigated the effects of detraining with an inclusion of a control group to control
for growth-related rises in muscular strength.
The maintenance of upper and lower body muscular strength improvements such as 1RM,
muscular endurance (20) or power (21) were observed in pubescent trained boys after 8
weeks (21) or 12 weeks (20) period of reduced strength training.
At the end of 8 weeks of detraining (absolute training cessation), Faigenbaum et al. (41)
observed that pre-pubescent untrained boys and girls, had significant loss 6RM leg
extension (-28.1 %) and chest press (-19.3%) strength. Lower limbs muscular strength
loss was made mainly during the first 4 weeks of detraining (6RM extension: -21.3%)
while upper limb muscular strength loss was about half during the first 4 weeks (chest
press: -8.9%) and albeit exercise group values remained significantly higher than control
group values. Nevertheless, at end of the 8-week detraining period, the chest press but not
leg extension strength of the subjects who have strength trained remained significantly
greater than controls. Concordantly, in pre- and early pubertal untrained males the same
trend can be found (117). After 8 weeks of detraining, Tsolakis et al. (117) fount that the
trained subjects' strength (concentric strength of the elbow flexion in the right arm,
assessed by an upper extremity dynamometer; and 10RM elbow flexion with adjustable
dumbbells) decreased significantly by 9.5%, converging toward the control values. The
weak degree of the initial strength gain and the detraining extent could partly explain the
reversible response of strength (10). Nevertheless, despite that observed strength loss, the
treatment group maintained about by 64% of the strength gained during training program,
probably due to the high intensity of the training program (63), which is an important
factor related to the magnitude of the improvement of the muscular strength (11).
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
44
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
In this line, the benefits of upper and lower body training (in pre- and early pubertal boys)
are lost at similar rates to other training modalities at the end of 12 weeks of training
recess (55).
Conversely, in pre- and early pubertal boys and girls swimmers, it was observed that at the
end of 6 weeks of detraining period strength parameters remained stable and swimming
performance still improved (47), however all the swimmers maintained the normal
swimming program, without any strength training. Thus, this study cannot be compared
with previous since subjects of treatment and controls continued on their usual swimming
training and thereby recess effects can be biased by swimming training.
Discussion
Despite of consensus exists from The British Association of Sport & Exercise Science,
(113), The American Academy of Pediatrics (2), The American College of Sports Medicine
(4,27), and the National Strength and Conditioning Association (41), with other
recommendations summarized by Faigenbaum et al. (40), Fulton et al. (46) and Twisk
(119), that resistance training since appropriately designed and supervised by expert
personnel is beneficial to children and adolescents’ athletic performance, health and
fitness, there is a scarcity of robustly designed studies investigating the main factors which
determine concurrent strength and endurance training gains and detraining effect (school
based) in untrained children and adolescents. Muscular strength has been recognized as
an important component of fitness in the recent evidence-based physical activity
guidelines for school-age youth (114). Despite there is clear data in adults (65) to support
these positions, evidence-based data in children and adolescents is limited. However,
available data suggest that well-designed and supervised resistance training programmes
may have beneficial health outcomes associated with aerobic fitness (27,113) and it would
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
45
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
be improvident to ignore those findings while the depth of evidence in non-adult
population is being established.
Our findings are important to increase de effectiveness of endurance and strength training
design of untrained children and adolescents in school context.
Aerobic training has been widely used in health related fitness training studies but
researches which have specifically investigated the better load components or school-
based programmes design to develop endurance training in untrained children and
adolescents are scarce. In our systematic search we could find that VO2max can increase in
pre- pubescent and post-pubescent children after an aerobic training programme and that
such an increase is of the same order in both genders when the initial aerobic fitness is
taken into account. Comparing with untrained youth, their trained counterparts had a
higher cardiac performance in ergometers’ tests, and this reached significance in pubertal
and post-pubertal girls. There is no consensus regarding to VO2max related gender
improvements differences in pre- and early pubescent subjects. In adolescents, it seems
that males increase aerobic capacity more than their age-counterparts. The usage of
different modes, intensities, durations (session and program) and objectives of the
programmes makes difficult the results comparisons (n=19 studies). Nevertheless, it was
found that the training program resulted in VO2max raise. Thus, more studies are needed
to clarify what is the best school-based program’s methodology on endurance training in
paediatric population.
When we considered the studies which have investigated strength training alone, we
found that prepubescent to early post-pubescent boys and girls who participate in a
resistance training programme can significantly raise upper and lower body strength
performance, enhance flexibility and improve body composition as well. Different training
Study One: Concurrent strength and aerobic training and detraining programs: effects on adolescents’ physical
fitness performance - Study review
46
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
modes are effective on strength training development of both trained and untrained or
pre- and pubescent boys and girls. Moreover, performing resistance training a minimum of
10-15 minutes twice a week, at a moderate volume is more effective and efficient than
performing at a higher volume. This is particularly important for school context since
usual available training resources do not allow the usage of high strength loads. When
considering gender effect, males seem to have greater strength improvements then
females.
In concurrent strength and aerobic training analysis we only considered the research that
has been investigated the concurrent strength and aerobic endurance training in untrained
youth. Concurrent training seems to be effective in pre-pubescent and post pubescent
boys and girls. It can be assumed that concurrent strength and endurance training not only
does not impair strength or endurance development as seems to be an effective, well-
rounded exercise program that can be used as a means to improve initial or general
strength in youth.
At last, studies that have been properly investigated the changes in resistance training-
induced strength gains during detraining in pre adolescents are still scarce and
insufficient. Different results have been found on detraining effect over subject’s strength
gains.
This study is consistant with previous studies which highlight the role of school as the
primary institution in physical fitness promoter.
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
47
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Study two - The effects of school-based strength training and concurrent
strength aerobic training programs on untrained boys.
The purpose of this study was to analyze the effects of power training alone and combined
strength and aerobic training on body composition, power strength and aerobic training
on a sample of healthy untrained school boys.
Methods
Experimental Approach to the Problem
Forty-two healthy boys recruited from a Portuguese public high school were randomly
assigned into two experimental groups (8 weeks training program, twice a week, from
April 13th to June 5th of 2009) and one control group as follows: one group performing
strength training only (GR: n=15); another group performing combined strength and
aerobic training (GCOM: n=15); and the third was the control group (GC: n=12; without a
training program). All sample subjects attended physical education classes twice a week,
with duration of 45 min and 90 min each class respectively. Typical physical education
classes included various sports (gymnastics, team sports, athletics, dancing, and adventure
sports, among others) with a clear pedagogical focus. As such, according to other
researchers (110) the physical activity intensity is considered low to moderate.
Participants in all groups were asked to maintain normal eating and physical activity
patterns over the duration of the study. This procedure was the same as Lubans et al. (73).
Usually, these classes start with jogging run lasting 10 min to general warm up; proceed to
joint mobilization and general stretches. After that the class is divided into 2 or 3
proficiency level groups to start the main activities/sports of the class, which can be a drill
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
48
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
or a game organized in small groups. In Portugal, a physical education class has a set of 45
min and another of 90 min twice a week.
The training program was implemented additionally to physical education classes in the
same outdoor sportive facility. After a 10 min warm up period, both experimental groups
were submitted to a power strength training program composed by: 1 and 3 kg medicine
balls throws performed as long and fast as possible; jumps onto a box (from 0.4 m to 0.6 m
of height); plyometric jumps above 0.4-0.6m of height hurdle (only one foot touch on the
floor among hurdles) and sets of 30 to 40m speed running. The GCOM group was
complementarily administered a 20m shuttle run training exercise (66), which occurred
immediately after the power strength training session. This endurance task was developed
based on an individual training volume - set to about 75% of the established maximum
aerobic volume achieved on a previous test. After 4 weeks of training, GCOM subjects were
reassessed using 20m shuttle run test in order to readjust the volume and intensity of the
20m shuttle run exercise. Both GR and GCOM trained on the same day of the week (with
two/three days between training sessions) and at the same morning hour. Subjects were
encouraged to hydrate before and at the middle of training session. All participants were
familiarised with powerful drills (sprints, jumps and ball throws) as well as with the 20m
shuttle run protocol. Throughout pre- and experimental periods, the subjects reported their
non-involvement in additional regular exercise programs for developing or maintaining
strength and aerobic performance besides institutional regular physical education classes.
The same training protocol design was followed in study three. A more detailed analysis of
the program can be found in table 1.
Sample groups were assessed for upper and lower body strength (overhead medicine ball
throwing and counter movement horizontal and vertical jumps, respectively), running
speed (20m sprint run) and VO2max (20m shuttle run test) before and after 8-weeks of
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
49
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
training program. Each subject was familiarised with power training tests (sprints, jumps
and ball throws) as well as with the 20m shuttle run test. All data collection was performed
by the same investigator and after a general warm-up of 10 minutes.
Table 1 - Training program design.
Sessions
Exercises 1 2 3 4 5 6
Chest 1 kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8 6x8 6x8
Chest 3 kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8
Overhead 1kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8 6x8 6x8
Overhead 3kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8
CMJ onto a box 1,2 1x5 1x5 3x5 3x5 3x5 4x5
Plyometric Jumps above 3 hurdling 1,2 5x4 5x4 5x4 5x4 2x3 2x3
Sprint Running (m) 1,2 4x20m 4x20m 3x20m 3x20m 3x20m 3x20m
20m Shuttle Run (MAV) 2 75% 75% 75% 75% 75% 75%
Sessions
Exercises 7 8 9 10 11 12
Chest 1 kg Medicine Ball Throw 1,2
Chest 3 kg Medicine Ball Throw 1,2 2x5 2x5 3x5 3x5 3x5 2x5
Overhead 1kg Medicine Ball Throw 1,2
Overhead 3kg Medicine Ball Throw 1,2 2x8 2x8 3x8 3x8 3x8
CMJ onto a box 1,2 4x5 5x5 5x5 5x5 5x5 4x5
Plyometric Jumps above 3 hurdling1,2 3x3 4x3 4x3 4x3 4x3
Sprint Running (m)1,2 4x30m 4x30m 4x30m 4x30m 4x30m 3x40m
20m Shuttle Run (MAV)2 75% TestM 75% 75% 75% 75%
Sessions
Exercises 13 14 15 16
Chest 1 kg Medicine Ball Throw 1,2 --- --- --- ---
Chest 3 kg Medicine Ball Throw 1,2 2x5 1x5 --- ---
Overhead 1kg Medicine Ball Throw 1,2 -- 3x8 2x8 2x8
Overhead 3kg Medicine Ball Throw 1,2 3x8 --- --- --
CMJ onto a box 1,2 4x5 2x5 2x4 2x4
Plyometric Jumps above 3 hurdling1,2 4x3 3x3 --- --
Sprint Running (m)1,2 3x40m 4x40m 2x30m 2x30m
20m Shuttle Run (MAV)2 75% 75% 75% 75% Legend: for the Medicine Ball Throwing and Jump onto box the 1st no. corresponds to sets and 2nd corresponds to repetitions. For Sprint Running 1st number corresponds to sets and 2nd corresponds to the distance to run. For 20m Shuttle Run training each girl ran each session (until testM) 75% of maximum individual aerobic volume performed on pre-test and after this testM moment until program end, ran 75% of maximum individual aerobic volume performed on testM. CMJ – Counter movement jump. MAV - maximum individual aerobic volume 1=power strength training protocol (GR). 2=concurrent resistance and endurance training (GCOM).
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
50
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Subjects
A sample of 42 healthy boys recruited from a Portuguese public high school (from 7th and
9th grades) was used in this study. To fulfill the ethical procedures of the Helsinki statement,
an informed consent was obtained prior to all testing adolescents’ parents. Efforts were
made to recruit subjects for making comparable groups. Maturity level based on Tanner
stages (42) was self-assessed: 51% were in Tanner Stage One and 49% were and Tanner
Stage Two. There were no significant differences (p>0.05) between groups for age or
Tanner ratings, neither in anthropometrics or performances variables at the beginning of
the protocol. No subject had regularly participated in any form of strength training prior to
this experiment. The following exclusion criteria were used: subjects with a chronic
paediatric disease or with an orthopaedic limitation.
Testing Procedures
Assessment procedures protocol used in this study was the same used in study three, four
and five.
Anthropometric assessment
Total height (m) was assessed according to international standards for anthropometric
assessment (77), with a Seca 264 Stadiometer (Hamburg, Deutschland). Body composition
variables were assessed using a Tanita body composition analyser; model TBF-300 (Tanita
Corporation of America, Inc, Arlington Heights, IL. USA) with a range of ratio of 1%-75%.
These parameters were assessed prior to any physical performance test. Subjects were
measured wearing shorts and t-shirts (shoes and socks were asked to be removed).
Overhead Medicine Ball Throwing
An overhead medicine ball throw test was used to evaluate the upper body ability to
generate muscular actions at a high rate of speed. Prior to baseline tests, each subject
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
51
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
underwent a familiarization session and was counseled on proper overhead throwing with
different weighted balls. Pre, posttests and detraining measurements were conducted on
maximal throwing velocity using medicine balls (Bhalla International - Vinex Sports,
Meerut - India) weighing 1kg (Vinex, model VMB-001R, perimeter 0.72m) and 3kg (Vinex,
model VMB-003R, perimeter 0.78m). A general warm-up period of 10 min, which included
throwing the 1- and 3kg weighted balls, was allowed. While standing, subjects held
medicine balls with 1 and 3kg in both hands in front of the body with arms extended. The
students were instructed to throw the ball over their heads as far and as fast as possible. A
counter movement was allowed during the action. One-minute of rest among 5 trials was
done. Only the best throw was considered for analysis. The ball throwing distance (BTd)
was recorded to the closest cm as proposed by van Den Tillaar & Marques (122). This was
possible as polyvinyl chloride medicine balls were used and when it falls on the Copolymer
Polypropylene floor a visible mark was made. The ICC of data for 1kg and 3 kg medicine
ball throwing was 0.97 and 0.99, respectively.
Counter movement Vertical Jump (CMVJ)
To monitor the effectiveness of an athlete's conditioning program, the standing vertical
jump test of leg power was used. The vertical jump test was conducted on a contact mat
connected to an electronic power timer, control box and handset (Globus Ergojump,
Codognè, Italy). From a standing position, with the feet shoulder-width apart and the
hands placed on the pelvic girth, the boys performed a counter movement with the legs
before jumping. Such movement makes use of the stretch-shorten cycle, where the muscles
are pre-stretched before shortening in the desired direction (72). They were informed that
they should try to jump vertically as high as possible. Each participant performed three
jumps with a 1-min recovery between attempts. The highest jump (cm) was recorded. The
counter movement vertical jump has shown an ICC of 0.95.
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
52
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Counter movement Standing Long Jump (CMSLJ)
In a standing long jump the jumper aimed to project his body for maximum horizontal
distance beyond a take-off line. The jumper started from a static standing position with
feet shoulder-width apart and then generated a large take-off speed by using a counter
movement coupled with the hands placed on the pelvic girth and a double-leg take-off. The
take-off is characterised by a large forward lean of the body, and during the flight phase
the jumper swings the legs forward underneath the body in preparation for landing. The
jumper landed with a prominent forward lean of the trunk and with the feet extended well
ahead of the hips. To be credited with a successful jump the jumper must retain balance
after landing and not fall backwards into the pit. A standing long jump performance was
quantified by the total jump distance, which is the distance from the take-off line to the
nearest break in the landing area made by the heels at landing (126). A fiberglass tape
measure (Vinex, MST-50M, Meerut, India) was extended across the floor and used to
measure horizontal distance. Each participant completed three trials with a 1-min
recovery between trials using a standardized jumping protocol to reduce inter-individual
variability. The greatest distance (cm) of the two jumps was taken as the test score. The
CMSLJ has shown an ICC of 0.96.
Sprint Running
This test was performed in an indoor school physical education facility with a Copolymer
Polypropylene floor; subjects wore adapted indoor shoes. Time to run 20m was obtained
using photocells (Brower Timing System, Fairlee, Vermont, USA). The time to run the
distance was recorded using a digital and automatic chronometer commanded by the cell
pad and a pair of photocells positioned above the 20m line. At the start moment each
subject trod the cell pad using the right hand with the time being recorded from when the
subjects intercepted the photocell beam. All subjects were encouraged to run as fast as
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
53
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
possible and to decelerate only after listening to the beep emitted by the last photocells pair.
Each student repeated the same procedure for 3 attempts and only the best time taken to
cover the 20 m distance in the sprint test was used in data analysis. A rest period of 10 min
among attempts was accomplished. The sprint running (time) has shown an ICC of 0.97.
20 Meters Shuttle Run (VO2max)
This test involves continuous running between two lines (20m apart in time) to recorded
beeps. The time between recorded beeps decreased each minute (level). We used the
common version with an initial running velocity of 8.5 km/h, and increments of 0.5 km/h
each minute (66). Estimated VO2max (ml.kg-1.min-1) was calculated by the Léger's equation
(66), which is based on the level and number of shuttles reached before boys were unable to
keep up with the audio recording. The 20m Shuttle Run test has shown an ICC of 0.96.
Statistical analyses
Standard statistical methods were used for the calculation of the means and standard
deviations (х±sd). One-way analysis of variance (ANOVA) was used to determine any
differences among the three groups’ initial power strength, running speed, endurance, and
anthropometry. The training related effects were assessed using a two-way ANOVA with
repeated measures (groups x moment). Selected absolute changes in each moment were
analyzed via one-way ANOVA. The p<0.05 criterion was used for establishing statistical
significance.
Results
There were no significant differences (p>0.05) between groups for age or Tanner stages,
neither in anthropometrics or performances variables at the beginning of the protocol
(p>0.05). Body fat (BF) decreased significantly (p=0.00) from pre - to the post-training
period in both GR and GCOM groups (Table 2); however, no significant differences were
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
54
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
found between groups. No significant changes were observed for total standing height, body weight
and body mass index (BMI) in both GC and GCOM groups. GR significantly changed in height (+1.2%,
p=0.004), BMI (-0.4%, p=0.00) and body fat (-10%, p=0.00) whereas GCOM only decreased in body
fat, but not significantly different from GR. From pre- to the post-training period no differences were
observed between experimental groups for performance variables, i.e., subjects from GCOM group
did not take advantage over subjects from GR group in jumps, running speed and balls throws tests.
However, VO2max increased significantly in GCOM (+4.6%, p<0.01), but remained unchanged in
both GC and GR groups. The magnitude of changes in 1Kg and 3kg ball throw distance, height in
CMVJ, length in CMSLJ and time to run 20 m was similar in both GR and GCOM groups (Table 3).
Table 2 - Descriptive (mean ± standard deviation) characteristics of the participants during three testing trials (M1 and M2) for all groups.
M1 M2 p value
Variable Group х±sd х±sd (M1-M2)
Body Weight (kg)
GC 56,5±11,2 56,9±11,0 0,22
GR 59,2±16,2 58,3±16,0 0,11
GCOM 51,4± 8,2 51,3± 8,2 0,85
Total Standing Height (cm) GC 163,8± 9,9 164,5± 9,8 0,06
GR 161,8±12,2 163,6±11,5 0,00†
GCOM 159,5± 8,1 160,2± 8,0 0,09
BMI (kg.m-2)
GC 21,0± 3,4 21,0± 3,6 0,74
GR 22,3± 4,6 21,6± 4,7 0,00†
GCOM 20,1± 2,1 19,9± 2,3 0,22
Body Fat (%)
GC 15,0± 6,4 14,1± 7,1 0,11
GR 18,2± 9,2 15,8± 8,4 0,00†
GCOM 14,5± 4,6 12,7± 4,6 0,00†
Legend: х – mean; sd- standard deviation; M1 – before training program; M2 – After training program; p(M1-M2)- p value for comparison between 2nd and 1st moment; GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, † - significant changes between moments.
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
55
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 3 – Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running Speed and VO2Max at all three test trials (M1 and M2) for each group.
Legend: х – mean; sd- standard deviation; CM – counter movement; M1 – before training program; M2 – After training program; p (M1-M2) - p value for comparison between 2nd and 1st moment, GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, ₮ - Significant changes between GC and GR, † - significant changes between moments.
M1 M2 p value
Group х±sd х±sd (M1-M2)
CM Vertical Jump (cm) GC 0,288±0,07 0,317±0,07 0,15
GR 0,293±0,07 0,306±0,07 0,04†
GCOM 0,298±0,08 0,316±0,09 0,02†
CM Standing Long Jump (m) GC 1,70±0,37 1,63±0,33 0,26
GR 1,49±0,27 1,56±0,30 0,00†
GCOM 1,67±0,31 1,74±0,32 0,00†
1kg Medicine ball throwing (m) GC 8,23±1,47 8,31±1,71 0,08
GR 7,50±1,70 8,15±1,62 0,00†
GCOM 7,26±1,60 7,59±1,73 0,04†
3kg Medicine ball throwing (m) GC 5,02±0,91 5,01±1,19 0,10
GR 4,66±0,98 5,12±1,08 0,00†
GCOM 4,60±1,12 5,11±1,17 0,04†
Running Speed 20m (s) GC 4,13±0,55 4,12±0,48 0,95
GR 4,54±0,49 4,05±0,42₮ 0,00†
GCOM 4,38±0,59 3,81±0,28 0,00†
VO2Max (mL.kg-1.min-1) GC 48,5±5,3 47,4±5,5 0,67
GR 45,2±6,4 46,8±6,5 0,10
GCOM 49,1±6,7 51,2±6,7 0,01†
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
56
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Discussion
To our best knowledge, no study prior to ours has established the effect of 8-weeks school
based strength training and aerobic program and detraining on strength, power and body
composition in adolescent boys, performed additionally to the physical education lessons.
Thus, it is difficult to compare the present results with other studies that have investigated
physical training cessation because they differ markedly in a number of factors, including
the sample and the method of measurement. The primary findings of the present study
indicate that both concurrent strength and aerobic training and strength raining alone may
be a positive training stimulus to enhance explosive strength and aerobic condition in
healthy schooled boys. Ours findings are in agreement with previous Gorostiaga et al. (50)
and Chtara et al. (18) studies conducted with adults. Simultaneously our results contradict
studies, which reported an impairment of concurrent training on performance variables
development (107). Additionally, both training regimens also showed a positive effect on
body fat loss in adolescent school boys. Therefore, the present results may suggest that
concurrent strength and aerobic training seems to be an effective, well-rounded exercise
program that can be prescribed as a means to improve initial or general strength in healthy
school boys. Concordantly the group submitted to strength and endurance program did not
show estimated VO2max loss in the detraining period.
The magnitude of decrease observed in BF was not significantly different between GR and
GCOM groups. We did not find any change in body weight for any group. It should be
highlighted that body weight does not always explain the true body composition and
therefore, despite we did not find body weight changes, we found body fat significant
losses in both experimental groups. However, we did not find significant differences
between experimental groups. These results may suggest that there is no major positive
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
57
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
effect of concurrent resistance and endurance training when body fat loss occurs.
Furthermore, the current results are in agreement with the research conducted by Watts
et al. (127) that examined an independent influence of 8 weeks of combined resistance and
aerobic training in 19 obese adolescents aged 12–16 year olds. On this, although
bodyweight and BMI did not change with exercise, significant improvements in central
adiposity were observed following the 8-week circuit-training program (127).
A significant increasing was observed for upper limb explosive strength (e.g. medicine ball
throw with 1kg and 3kg), in both GCOM and GR groups. This data may suggest a positive
main effect of resistance training on explosive strength ability independently of type of
treatment performed. In accordance to the upper body strength results, the explosive
power of lower limbs revealed by the CMVJ and CMSLJ performance also increased
significantly for both experimental groups. Few studies, however, have compared the
effects of different methods of organizing training workouts. Here, for example, Sale et al.
(100) could observe that concurrent strength and aerobic training applied on separate
days produced superior gains to those produced by concurrent training on the same day.
Although the training programs were held otherwise constant, alternate-day training was
more efficient in producing maximal leg press strength gains than same-day training. This
suggests that the interference effect may also be true when the overall frequency and/or
volume of training are higher than in this particular study. Also Ingle et al. (55) using a
combination of strength training and plyometric program, found the experimental group
saw a small improvement in performance over the training intervention period. Our
results also demonstrated that the aerobic training does not positively affect strength
development in school boys. In addition, however, the present research showed that
concurrent resistance and endurance training does not impair strength development.
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
58
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Unfortunately, it is difficult to compare results in the scientific literature when studies
differ markedly in their design factors including load characteristics, context, equipment,
scheduling of training sessions and training history of subjects (70,124). Therefore, further
research is required to investigate these causes and identify other possible mechanisms
responsible for the observed inhibition in strength development after concurrent training
(100).
Running speed increased significantly in all experimental groups. In agreement with
previous studies (78), these results seem to indicate that additional endurance training does
not have an additional effect over strength training to enhance running speed in young boys.
On the other hand, all students approached various sports during Physical Education
classes. Although physical activity intensity can be considered low to moderate, some sports
(for instance, soccer and basketball) elicit high intensity performances (sprints) and low-
intensity periods, which could have enhanced running speed performance.
An inhibition in strength or aerobic adaptations as a consequence of concurrent training has
been reported (124). Nevertheless, the present study could observe a significant
enhancement in VO2max (ml.kg-1.min-1) only for GCOM, suggesting that the strength training
program component was not effective to a rising in aerobic fitness for young school boys.
Our data suggest that dependent variable selection can influence conclusions made with
respect to changes in strength and endurance as a result of concurrent training. However,
differences in the design of concurrent training interventions, such as mode, duration, and
intensity of training, may influence whether any interference in strength or endurance
development is observed. Clearly, the interaction between strength and endurance training
is a complex issue, and it may still be possible to design specific concurrent training
regimens that can minimize or possibly avoid any interference effects.
Study two - The effects of school-based strength training and concurrent strength aerobic training programs
on untrained boys
59
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Conclusions
Our results suggest that a concurrent strength and aerobic school-based training program
seems considerably effective on both strength and endurance fitness feature of age-school
boys. However, the strength training program also produced identical results on strength
development. In brief, the present study indicates that performing simultaneously strength
and aerobic training in the same workout not only does not impair strength development in
healthy school boys but also seems to be an effective, well-rounded exercise program that
can be prescribed as a means to improve initial or general strength. This should be
considered in designing strength training school-based programs in order to improve its
efficiency.
Future researches must examine the interference effects arising from the order of strength
and aerobic training exercises program for strength enhancement.
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
60
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Study three - The effects of school-based strength training and
concurrent strength and aerobic training programs on untrained girls.
The main purpose of the current study was to analyze the effects of strength training
alone, or combined strength and aerobic training on body composition, strength and
cardiovascular markers on a sample of healthy schoolgirls.
Methods
Experimental Approach to the Problem
Sixty-seven healthy girls (13.5±1.03 years old) recruited from a Portuguese public high
school were divided into two experimental groups (8 weeks training program, twice a
week, from April 12th to June 4th of 2010) and one control group as follows: one group
performing strength training only (GR: n=21); another group performing combined
strength and endurance training (GCOM: n=25); an additional group as control (GC: n=21;
without training program). Experimental approach details, assessment and training’s
protocol are the same used in study two.
Subjects
A sample of 67 healthy girls recruited from a Portuguese public high school (from 7th and
9th grades) was used in this study. To fulfill the ethical procedures of the Helsinki
statement (132), a consent form was obtained prior to all the testing from parents or a
legal guardian of the adolescents. Efforts were made to pick subjects for making
comparable groups. Maturity level based on Tanner stages (25) was self-assessed: 48%
were in Tanner Stage One and 52% were and Tanner Stage Two. Students were asked to
answer to an image with corresponding legend questionnaire. Students answered the
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
61
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
questionnaire in an individual booth without interference from their teachers or school
friends. There were no significant differences (p>0.05) between groups for age or Tanner
stages, neither in strength or endurance fitness performances at the beginning of the
protocol. No subject had regularly participated in any form of strength training program
prior to this experiment. The following exclusion criteria were used: subjects with a
chronic paediatric disease or with an orthopaedic limitation.
Statistical analyses
Statistical analysis used in this study was the same as used in study two.
Results
At baseline, no significant differences were observed between groups for any of the pre-
training anthropometrics and performance variables (p>0.05). Body fat (BF) significantly
decreased (p<0.01) from the pre-training to the post-training period in all groups (table 4).
No significant changes were observed for height, body weight and body mass index (BMI)
in any of the groups. Only GCOM increased significantly 1kg and 3kg ball throw distance
(p<0.05). GR increased significantly 3kg ball throw distance (p<0.05) (Table 5). The CMVJ
height remained stable after the training program for group GR (0%; ns) whereas GR
(+8%; 0.01) and GCOM (+12%; 0.00) significantly increased CMVJ height after the training
program. Both experimental groups also increased their performance in CMSLJ after the
training program: GR (+0.8%; 0.04) and GCOM (+5.4%; 0.01). GC (-2.3%; ns) didn’t change
significantly CMSLJ height in the same period. The time to run 20m significantly decreased
in GR (-11.5%, p=0.00) and GCOM (-10%, p=0.00), whereas remained constant in GC. The
amount of changes was similar in both GR and GCOM groups. Finally, the VO2max
increased significantly in both GC (+3.2%, p<0.05) and GCOM (+4.0%, p<0.01), whereas it
remained unchanged in GR group.
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
62
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 4 - Descriptive (mean ± standard deviation) characteristics of the participants during three testing trials (M1 and M2) for all groups.
Variable Group M1 M2 p value
х±sd х±sd (M1-M2)
Body Weight (kg)
GC 51,5±11,1 53,9±12,7 0,39
GR 58,9±13,5 59,0±14,1 0,95
GCOM 54,8±17,1 54,5±18,0 0,64
Total Standing Height (cm) GC 156,8±6,5 158,3±6,9 0,06
GR 159,4±6,1 159,4±6,0 0,14
GCOM 157,9±8,2 158,0±7,8 0,79
BMI (kg.m-2)
GC 20,9±4,0 21,6±4,7 0,68
GR 23,0±4,1 23,0±4,5 0,35
GCOM 21,6±5,3 21,6±5,4 0,24
Body Fat (%)
GC 24,34±6,5 24,29±7,8₮ 0,01†
GR 32,14±7,7 30,16±8,2 0,00†
GCOM 26,79±9,9 24,23±10,4¥ 0,00†
Legend: х – mean; sd- standard deviation; M1 – before training program; M2 – After training program; p(M1-M2)- p value for comparison between 2nd and 1st moment, GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, ₮ - Significant changes between GC and GR; ‡ - Significant changes between GC and GCOM; ¥ - Significant changes between GR and GCOM; † - significant changes between moments.
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
63
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 5 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running Speed and VO2Max at all three testing trials (M1 and M2) for each group.
Variable
Group M1 M2 p value
х±sd х±sd (M1-M2)
1Kg Medicine ball throwing (m) GC 5,91±0,83 5,76±0,57 0,29
GR 6,43±1,26 6,80±1,34₮ 0,08
GCOM 6,14±1,00 6,67±1,16‡ 0,00†
3Kg Medicine ball throwing (m) GC 3,79±0,50 3,76±0,43 0,37
GR 3,93±0,73 4,29±0,74₮ 0,01†
GCOM 3,89±0,64 4,25±0,73‡ 0,00†
CM Vertical Jump (cm) GC 0,26±0,07 0,26±0,06 0,13
GR 0,25±0,06 0,27±0,07 0,01†
GCOM 0,25±0,06 0,28±0,08 0,00†
CM Standing Long Jump (m) GC 1,32±0,23 1,29±0,20 0,17
GR 1,31±0,24 1, 32±0,26 0,04†
GCOM 1,30±0,26 1,37±0,22 0,01†
Running Speed 20m (s) GC 4,42±0,44 4,20±0,36 0,10
GR 4,91±0,57 4,28±0,38 0,00†
GCOM 4,80±0,53 4,25±0,34 0,00†
VO2Max (mL.kg-1.min-1) GC 40,8±4,05 41,0±4,27 0,05†
GR 39,2±4,29 40,7±3,98 0,13
GCOM 42,5±4,37 43,7±4,09‡¥ 0,01†
Legend: х – mean; sd- standard deviation; CM – counter movement; M1 – before training program; M2 – After training program; p (M1-M2) - p value for comparison between 2nd and 1st moment; GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, ₮ - Significant changes between GC and GR; ‡ - Significant changes between GC and GCOM; ¥ - Significant changes between GR and GCOM; † - significant changes between moments.
Discussion
The primary findings of the study showed that concurrent strength and aerobic training
may be a positive training stimulus to induce power strength and aerobic fitness
development and also showed a majorly positive effect on body fat loss in adolescent
school girls. Therefore, the present results may suggest that concurrent strength and
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
64
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
aerobic training seems to be an effective, well-rounded exercise program that can be used
as a means to improve initial or general strength in healthy school girls.
In GCOM, the magnitude of decrease observed in BF was significantly greater (-11.4%,
p=0.01) than that observed in GR (-6.2%, p=0.03). However, we did not find any change in
body weight and BMI for any group. These results suggest a major positive effect of
concurrent strength and endurance training over body fat loss occurs. This could be
related to the fact that aerobic exercise can contribute an increase on fat metabolism. In
fact, it is known that insulin sensitivity increases with aerobic training and also has an
effect on glucose transportation; insulin has an anabolic effect on fat storage in the fat cells
(90). Insulin affects appetite regulation through the change in substrates in the blood.
Insulin sensitivity may therefore be one of the key mechanisms behind the association
found between body composition and fitness (90). Furthermore, although the design of the
training intervention of this study is different from the research conducted by Watts et al.
(127), the current results are in agreement with their study results. Watts et al. (127)
examined 19 obese adolescents aged 12–16 years independent influence of 8 weeks of
concurrent strength and aerobic training. Here, although bodyweight and BMI has not
changed with exercise, significant improvements in central adiposity were observed
following the 8-week circuit-training programme (135). Moreover, the total body fat
decreased but the majority of fat tissue mass was lost from the abdominal and trunk areas.
Interestingly, subcutaneous (skinfold) fat measures did not change, even in these areas,
suggesting that exercise training may beneficially modify body composition, with initial
decreases in fat predominantly occurring from the viscera (135).
Upper body power (e.g. the medicine ball throws with 1kg and 3Kg) has significantly
increased in both GCOM and GR group. This data may suggest a positive influence of
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
65
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
strength training on power strength performance results, no matter with or without
concurrent strength and endurance training. Concordantly to the upper body strength
results, the power of lower limbs revealed by the CMVJ and CMSLJ performance has
changed for both experimental groups. To our knowledge, few studies have compared the
effects of different methods of organising training workouts. For example, Sale et al. (100)
observed that concurrent strength and endurance training applied on separate days
produced gains superior to those produced by concurrent training on the same day.
Although the training programs were held otherwise constant, alternate-day training was
more effective in producing maximal leg press strength gains than same-day training. This
suggests that the interference effect may also be true when the overall frequency and/or
volume of training are higher than in this particular study. Briefly, the results do not
demonstrate the universality of the interference effect in strength development when
strength training is performed concurrently with endurance training in school girls. It is
difficult to compare the results in scientific literature when studies differ markedly in their
design factors including mode, frequency, intensity, volume of training, and training
history of subjects (106,56). Therefore, further research is required to investigate these
causes and identify other possible mechanisms responsible for the observed inhibition in
strength development after concurrent training (127).
Running speed increased significantly in all experimental groups. These results seem to
indicate that additional endurance training doesn't have an additional effect over strength
training to enhance running speed in young girls. On the other hand, all students took part
in various sports during Physical Education classes. Although physical education intensity
can be considered low to moderate, some sports (for instance, soccer and basketball) bring
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
66
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
high intensity performances (sprints) and low-intensity periods, which could have
enhanced running speed performance.
Many people rationalise that concurrent training will give them the benefits of both
strength and endurance training (1). The fact that an inhibition in strength or aerobic
adaptations as a consequence of concurrent training has been reported (125). The present
study, however, could observe a significant enhancement in VO2max (ml.kg-1.min-1) for
both GC and GCOM, suggesting that the aerobic training program component was effective
to a rising in aerobic fitness independently of the treatment group. Our data suggest that
dependent variable selection can influence conclusions made with respect to changes in
strength and aerobic as a result of concurrent training. However, differences in the design
of concurrent training interventions, such as mode, duration, and intensity of training, may
influence whether any interference in strength or aerobic development is observed.
Clearly, the interaction between strength and aerobic training is a complex issue, and it
may still be possible to design specific concurrent training regimens that can minimize or
possibly avoid any interference effects.
Conclusions
Overall, our results suggest that concurrent strength and aerobic school-based training
programs seem more effective on both strength and endurance fitness feature of age-
school girls. In other words, our study indicates that concurrent training is an effective,
well-rounded exercise program that can be set up as a means to improve initial or general
strength in healthy school girls. Moreover, performing simultaneously strength and
aerobic training in the same workout does not impair strength development in young girls,
which has important practical relevance for the construction of strength training in school-
based programs. Future studies should examine the interference effects arising from the
Study three - The effects of school-based strength training and concurrent strength and aerobic training
programs on untrained girls
67
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
arrangement of strength and endurance training exercises (e.g., endurance training before
strength training or vice versa) on strength.
Study four - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained boys
68
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Study four - The effects of a detraining period on body composition and
performance variables after school-based strength and concurrent
strength and aerobic training programs on untrained boys.
The purpose of this study was to assess the effects of a detraining period on strength, power
and aerobic performances as well as in body composition in boys.
Methods
Experimental Approach to the Problem
The same forty-two healthy boys recruited for study two were recruited for this study. The
onset of this study was coincident with the ending of study two (study four lasted from
2009, 5th June to 2009, 28th August). Participants in all groups were asked to maintain
normal eating and informal physical activity patterns over the duration of the study. This
procedure was the same as Lubans et al. (73). Throughout detraining period, the subjects
reported their non-involvement in formal exercise programs for developing or
maintaining strength and aerobic performance.
Sample’s groups were assessed for upper and lower body explosive strength (overhead
medicine ball throwing and counter movement horizontal and vertical jumps,
respectively), running speed (20m sprint run) and VO2max (20m shuttle run test) after 12
weeks of study two had stopped. The DT period was coincident with the summer holidays.
The assessment procedures and protocol were the same used in studies two and three and
five. The testing assessment procedures were always conducted in the same indoor
environment, at the same daily and weekly schedule. Each subject was familiarised with
power training tests (sprints, jumps and ball throws) as well as with the 20m shuttle run
Study four - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained boys
69
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
test. All data collection was performed by the same investigator and after a general warm-
up of 10 minutes.
Subjects
As we mentioned in the previous point the same forty-two healthy boys recruited for study
two were recruited for this study. To fulfill the ethical procedures of the Helsinki statement,
an informed consent was obtained prior to all testing adolescents’ parents.
Testing Procedures
The assessment procedures and protocol were the same used in study two.
Statistical analyses
Standard statistical methods were used for the calculation of the means and standard
deviations (х±sd). One-way analysis of variance (ANOVA) was used to determine any
differences among the three groups’ power strength, running speed, endurance, and
anthropometry. The detraining related effects were assessed using a two-way ANOVA with
repeated measures (groups x moment). The p<0.05 criterion was used for establishing
statistical significance.
Results
Detraining period resulted in decreased body weight (-2.7%, p=0.03) for GCOM (table 6),
whereas it remained constant for GR and GC groups. Body height increased significantly
for GR (+0.6%, p=0.00) and GCOM (+0.7%, p=0.01). No significant changes were observed
in BMI from post-training to detraining period in any group. No significant changes were
observed in body fat loss in any of the experimental groups.
Study four - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained boys
70
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 6 - Descriptive (mean ± standard deviation) characteristics of the participants during three testing trials (M2 and M3) for all groups.
M2 M3 p value
Variable Group х±sd х±sd (M2-M3)
Body Weight (kg)
GC 56,9±11,0 56,8± 4,9 0,14
GR 58,3±16,0 58,9±16,7 0,28
GCOM 51,3± 8,2 50,8± 7,3 0,03†
Total Standing Height (cm) GC 164,5± 9,8 167,1±9,7 0,08
GR 163,6±11,5 163,9±11,8 0,00†
GCOM 160,2± 8,0 161,3± 7,9 0,01†
BMI (kg.m-2)
GC 21,0± 3,6 20,6± 3,0 0,17
GR 21,6± 4,7 22,0± 5,0 0,26
GCOM 19,9± 2,3 20,3± 2,7 0,22
Body Fat (%)
GC 14,1± 7,1 12,8± 6,6 0,74
GR 15,8± 8,4 17,0± 8,6 0,36
GCOM 12,7± 4,6 12,5± 4,6 0,75
Legend: х – mean; sd- standard deviation; M2 – After training program; M3 – After detraining period; p(M2-M3) - p value for comparison between 3th and 2nd moment; GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training; † - significant changes between moments.
No significant changes were observed in 1kg and 3kg medicine ball throw gains after the
DT period in any groups (Table 7). No significant changes in vertical jump height,
horizontal jump length, and time to run 20m after the DT period were observed after the
detraining period (Table 7). Estimated VO2max, however, decreased after the DT period in
GR group (-6.8%, p=0.04) but not in GCOM. No significant differences were found between
groups.
Study four - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained boys
71
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 7 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running Speed and VO2Max at all three testing trials (M2 and M3) for each group.
Legend: х – mean; sd- standard deviation; CM – counter movement; M2 – After training program; M3 – After detraining period; p (M2-M3) - p value for comparison between 3th and 2nd moment; GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, ₮ - Significant changes between GC and GR; † - significant changes between moments.
M2 M3 p value
Group х±sd х±sd (M2-M3)
CM Vertical Jump (cm) GC 0,317±0,07 0,317±0,09 0,71
GR 0,306±0,07 0,277±0,08 0,14
GCOM 0,316±0,09 0,295±0,10 0,37
CM Standing Long Jump (m) GC 1,63±0,33 1,62±0,51 0,72
GR 1,56±0,30 1,47±0,36 0,17
GCOM 1,74±0,32 1,54±0,43 0,12
1kg Medicine ball throwing (m) GC 8,31±1,71 8,89±1,75 0,11
GR 8,15±1,62 8,13±1,45 0,31
GCOM 7,59±1,73 7,71±2,27 0,37
3kg Medicine ball throwing (m) GC 5,01±1,19 5,35±1,30 0,15
GR 5,12±1,08 5,10±0,99 0,29
GCOM 5,11±1,17 5,03±1,25 0,97
Running Speed 20m (s) GC 4,12±0,48 3,52±0,49 0,12
GR 4,05±0,42₮ 4,04±0,36 0,43
GCOM 3,81±0,28 3,83±0,50 0,93
VO2Max (mL.kg-1.min-1) GC 47,40±5,5 44,4±8,1 0,52
GR 46,80±6,5 42,1±5,2 0,04†
GCOM 51,20±6,7 51,7±6,6 0,83
Study four - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained boys
72
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Discussion
Twelve consecutive weeks in summer holidays were taken as detrained period. All sample
subjects had no formal physical activity (Physical Education lessons or institutional
training programs) during DT period. The primary findings of the present study indicate
that both training programs-regimens’ effects persisted as long as upper and lower limb
strength gains were kept during 12 weeks of the detraining period. Concordantly the
group submitted to strength and endurance program did not show estimated VO2max loss
in detraining period.
Only the GCOM significantly decreased body weight (-1.7%, p=0.03). In Total Standing
Height variable, both experimental groups had a significant increase from post-training to
detraining moment. There was no significant difference in BMI on GR group from post-
training to detraining moment. Additionally, there was no significant difference in BF
percentage loss between GR and GCOM during the intervention period. Thus, we can
assume that the sustainment of BF obtained with training programs participation is visible
for several weeks after the programme has finished. Conversely to post-training moment,
all groups had shown no significant loss performance on CMVJ and CMSLJ. In speed
running a significant loss performance was expected but it was not found in both GR and
GCOM. A possible loss was expected as speed running is strongly affected by nervous
system adaptation and phosphocreatine reserves; however, it was not observed (45). In
the 1 and 3 kg medicine ball throw distance test, no significant changes were observed for
experimental groups, which mean a sustained effect of training in this explosive task. Our
results are in disagreement with Ingle et al findings (55), which in a detraining 12-week
period the experimental group saw reductions for all of the resistance exercises that
ranged from -16.3 to -30.3%. The control group also had no differences in performance
Study four - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained boys
73
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
marks for both 1 and 3Kg medicine ball throw distance test. Therefore, it must be
suggested that explosive strength gains induced by both training programs were kept after
a DT period of 12 weeks, as strength is determined, among other factors, by muscular
mass. Faigenbaum et al. (29) showed that 8 weeks of detraining led to significant losses of
leg extension (-28.1 %) and chest press (-19.3%) strength whereas control group strength
scores remained relatively unremarkable.
Finally, the VO2max (ml.kg-1.min-1) remained stable for GCOM, except for GR where a
significantly loss (-6.8%) was observed. Another study (83) found that changes are more
moderate in recently trained subjects (compared with highly trained subjects) in the short-
term, but recently acquired VO2max gains are completely lost after training stoppage
periods longer than 4 weeks. Conversely, our results show that GCOM kept VO2max gains
even after 12 weeks of DT. The detraining effect over VO2max has been poorly studied in
non-adult and non-sportive samples. Hence, due to the small sample size and the lack of a
pre-study power analysis to determine adequate effect size for this study, we suggest that
our subgroup analyses and results must be interpreted with caution.
Conclusions
Our results suggest that training program effects persists even at the end of detraining
period. Those effects include body composition improvements, and physical fitness
components as strength and aerobic capacities. School-based programs should be
implemented since training programs’ effects persist at the end of summer holidays on body
composition and physical fitness level.
Study five - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained girls
74
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Study five - The effects of a detraining period on body composition and
performance variables after school-based strength and concurrent
strength and aerobic training programs on untrained girls.
The main purpose of the current study was to assess the effects of a detraining period on
strength and aerobic performance of schoolgirls.
Methods
Experimental Approach to the Problem
The same sixty-seven healthy girls (13.5±1.03 yrs) recruited for study three were recruited
for this study. The onset of this study was coincident with the ending of study three (study
five lasted from 2010, 4th June to 2010, 27th August). Participants in all groups were asked to
maintain normal eating and informal physical activity patterns over the duration of the
study. This procedure was the same as Lubans et al. (73). Throughout detraining period, the
subjects reported their non-involvement in formal exercise programs for developing or
maintaining strength and endurance performance.
Sample groups were assessed for upper and lower body explosive strength (overhead
medicine ball throwing and counter movement horizontal and vertical jumps, respectively),
running speed (20m sprint run) and VO2max (20m shuttle run test) after 12 weeks of study
three had stopped. The DT period was coincident with the summer holidays. The
assessment procedures and protocol were the same used in studies two, three and four. The
testing assessment procedures were always conducted in the same indoor environment, at
the same daily and weekly schedule. Each subject was familiarised with power training tests
(sprints, jumps and ball throws) as well as with the 20m shuttle run test. All data collection
was performed by the same investigator and after a general warm-up of 10 minutes.
Study five - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained girls
75
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Subjects
As we mentioned in previous point the same 67 healthy girls (from 7th and 9th grades)
recruited for study three were recruited to this study. To fulfill the ethical procedures of the
Helsinki statement, an informed consent was obtained prior to all testing adolescents’
parents.
Testing Procedures
The assessment procedures and protocol were the same used in study three.
Statistical analyses
The same procedure as used in study four.
Results
The detraining period resulted in an increase in body weight (+1.6%, p<0.04) for GCOM
(table 8), whereas remained constant for the GR and GC groups. Body height increased
significantly for GR (+0.2%, p<0.03). No significant changes were observed in the 1kg and
3kg medicine ball throw gains after the DT period in any of the experimental groups (Table
9). Additionally, table 3 shows that all groups had significantly lower scores in the vertical
jump height after DT period: less 23.1% for GC (p=0.00), less 3.7% for GR (p=0.02) and less
14.3% for GCOM (p=0.00). Significant differences were found between GC and GR as well as
between GR and GCOM groups. Both GC (+1.6%; ns) and GR (-3.8%; ns) didn’t change their
CMSLJ performance after the detraining period. However, GCOM (-4.4%; 0.00) has reduced
CMSLJ height in the same period. The time to run 20m decreased in GC and GCOM (1.2% and
1.9%, respectively), yet no significant differences between groups were observed after DT.
Estimated VO2max remained unchanged after DT period in all groups.
Study five - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained girls
76
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 8 - Descriptive (mean ± standard deviation) characteristics of the participants during three testing trials (M2 and M3) for all groups.
Variable Group M2 M3 p value
х±sd х±sd (M2-M3)
Body Weight (kg)
GC 53,9±12,7 51,9±12,2 0,99
GR 59,0±14,1 60,4±15,4 0,56
GCOM 54,5±18,0 55,2±18,3 0,04†
Total Standing Height (cm) GC 158,3±6,9 158,9±6,9 0,34
GR 159,4±6,0 160,2±6,3 0,03†
GCOM 158,0±7,8 158,2±7,9 0,07
BMI (kg.m-2)
GC 21,6±4,7 20,9±4,9 0,65
GR 23,0±4,5 23,2±5,4 0,62
GCOM 21,6±5,4 21,8±5,6 0,12
Body Fat (%)
GC 24,29±7,8₮ 22,42±8,8 0,79
GR 30,16±8,2 31,53±8,6₮ 0,30
GCOM 24,23±10,4¥ 25,34±11,1 0,30
Legend: х – mean; sd- standard deviation; M2 – After training program; M3 – After detraining period; p(M2-M3) - p value for comparison between 3th and 2nd moment; GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, ₮ - Significant changes between GC and GR; ‡ - Significant changes between GC and GCOM; ¥ - Significant changes between GR and GCOM; † - significant changes between moments.
Study five - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained girls
77
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Table 9 - Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing, Running Speed and VO2Max at all three testing trials (M2 and M3) for each group.
Variable
Group M2 M3 p value
х±sd х±sd (M2-M3)
1Kg Medicine ball throwing (m) GC 5,76±0,57 5,57±0,52 0,23
GR 6,80±1,34₮ 6,73±1,18₮ 0,06
GCOM 6,67±1,16‡ 6,69±1,18‡ 0,78
3Kg Medicine ball throwing (m) GC 3,76±0,43 3,59±0,50 0,03†
GR 4,29±0,74₮ 4,67±1,34₮ 0,23
GCOM 4,25±0,73‡ 4,25±0,74‡ 0,49
CM Vertical Jump (cm) GC 0,26±0,06 0,20±0,04 0,02†
GR 0,27±0,07 0,26±0,06₮ 0,02†
GCOM 0,28±0,08 0,24±0,06‡ 0,00†
CM Standing Long Jump (m) GC 1,29±0,20 1,31±0,31 0,50
GR 1, 32±0,26 1,27±0,29 0,23
GCOM 1,37±0,22 1,31±0,30 0,05†
Running Speed 20m (s) GC 4,20±0,36 4,25±0,36 0,03†
GR 4,28±0,38 4,32±0,40 0,86
GCOM 4,25±0,34 4,33±0,39 0,00†
VO2Max (mL.kg-1.min-1) GC 41,0±4,27 45,0±8,20 0,21
GR 40,7±3,98 42,0±6,84 0,58
GCOM 43,7±4,09‡¥ 41,9±5,80 0,43
Legend: х – mean; sd- standard deviation; CM – counter movement; M2 – After training program; M3 – After detraining period; p (M2-M3) - p value for comparison between 3th and 2nd moment; GC – Control Group, GR – resistance training group, GCOM - concurrent resistance and endurance training, ₮ - Significant changes between GC and GR; ‡ - Significant changes between GC and GCOM; ¥ - Significant changes between GR and GCOM¸† - significant changes between moments.
Discussion
The detraining period coincided with the summer holidays (e.g. 12 consecutive weeks).
Thus, sample subjects had no formal physical activity (Physical Education lessons or
institutional training programs) during this period. Despite that physical activity had
decreased in an overall view, all groups kept body composition. Only the GCOM increased
significantly in body weight (+1.6%) but not BF. Additionally, the biggest BF percentage
Study five - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained girls
78
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
loss was noticed in GCOM during the intervention period (study three). Therefore, we can
assume that the sustainment of BF obtained within the training programs participation is
visible for several weeks after the programme has finished. Regarding to CMVJ, all groups
had shown a significant loss of performance trend (p<0.02). However, in CMSLJ only GCOM
had significantly reduced (p<0.01) performance during the detraining recess. This
decrement is not surprising since GCOM had a higher increase (however not significantly
different from GR) during the training period. In speed running a significant loss of
performance was found in GC and GCOM, but not in GR. This loss was expected as speed
running is strongly affected by the nervous system adaptation and phosphocreatine
reserves. In the 1 and 3Kg medicine ball throw distance test, no significant changes were
observed for the experimental groups, despite an overall increase in performance, which
means a more sustained effect of training in this power task. The control group had the
worst performance marks for both the 1 and 3Kg medicine ball throw distance test. Yet,
only the 3kg medicine ball throw distance test, change was significant. For both variables,
differences were found between GC and GR as well as between GC and GCOM. Thus, power
strength gains from both training programs were kept after a DT period of 12 weeks, as
strength is determined, among other factors, by muscular mass. Faigenbaum et al. (1996)
results show that the 8 weeks of detraining led to significant losses of leg extension (-28.1
%) and chest press (-19.3%) strength whereas the control group strength scores remained
relatively similar. Finally, the VO2max (ml.kg-1.min-1) remained stable for all groups, except
for GCOM where a significant loss (-4.3%) was observed. Mujika & Padilla (2001) found
that changes are more controlled in recently trained subjects (compared with highly
trained subjects) in the short-term, but recently acquired VO2max gains are completely lost
Study five - The effects of a detraining period on body composition and performance variables after school-
based strength and concurrent strength and aerobic training programs on untrained girls
79
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
after training ceases for a period longer than 4 wks. Conversely, our results show that
GCOM kept VO2max gains even after 12 wks of DT.
Conclusions
Overall, our results suggest that the detraining period was not sufficient to reduce the
overall training effects on body composition and performance variables.
Overall discussion and conclusions.
80
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Overall discussion
Aerobic training has been widely used in health related fitness training studies but
researches which have been specifically investigated the better load components or
school-based programmes design to develop endurance training in untrained children and
adolescents are scarce. In our systematic search we could find that VO2max can increase in
children after an aerobic training programme and that such an increase is of the same
order in both genders when the initial aerobic fitness is taken into account. Comparing
with untrained youth, their trained counterparts had a higher aerobic performance in
ergometers tests, and this reached significance in pubertal and post-pubertal girls. There is
no consensus regarding to VO2max related gender improvements differences in pre- and
early pubescent subjects. In adolescent, it seems that male increase aerobic capacity more
than their age-counterparts. The usage of different modes, intensities, durations (session
and program) and objectives of the programmes makes difficult the results comparisons
(n=19 studies). Nevertheless, it was found that training programme resulted in VO2max
raise. Thus, more studies are needed to clarify what is the best school-based program’s
methodology on aerobic training in paediatric population.
When we considered the studies which have investigated strength training alone, we
found that prepubescent to early post-pubescent boys and girls who participate in a
strength training programme can significantly raise upper and lower body strength
performance, enhance flexibility and improve body composition as well. Different training
modes are effective on strength training development of both trained and untrained or
pre- and pubescent boys and girls. Moreover, performing resistance training a minimum of
10-15 minutes twice a week, at a moderate volume is more effective and efficient than
Overall discussion and conclusions.
81
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
performing at a higher volume. This is particularly important for school context since
usual available training resources do not allow the usage of high strength loads. When
considering gender effect, males seem to have greater strength improvements then
females.
In concurrent strength and aerobic training analysis we only considered the research that
has been investigated the concurrent strength and aerobic endurance training in untrained
youth. Concurrent training seems to be effective in pre-pubescent and post pubescent
boys and girls. It can be assumed that concurrent strength and endurance training not only
does not impair strength or endurance development as seems to be an effective, well-
rounded exercise program that can be used as a means to improve initial or general
strength in youth.
At last, studies that have been properly investigated the changes in resistance training-
induced strength gains during detraining in pre adolescents are still scarce and
insufficient. Different results have been found on detraining effect over subject’s strength
gains. However, it can be assumed that even after a period as long as 3 month, strength
and endurance gains can be observed in untrained early to post-pubescent boys and girls.
Ours study review is consistent with previous studies which highlight the role of school as
the primary institution in physical fitness promoter.
Training effects
To our best knowledge, no other study has established the effect of 8-weeks school based
endurance and resistance training program and detraining on strength, power and body
composition in adolescent boys, performed additionally to the physical education lessons.
Thus, it is difficult to compare the present results with other studies that have investigated
Overall discussion and conclusions.
82
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
physical training cessation because they differ markedly in a number of factors, including
the sample and the method of measurement. The primary findings of the present study
indicate that both concurrent resistance and endurance training and resistance training
alone may be a positive training stimulus to enhance explosive strength and aerobic
condition in healthy schooled boys and girls. Ours findings are in agreement with previous
Gorostiaga et al. (50) and Chtara et al. (18) studies conducted with adults. Simultaneously
our results contradict studies, which reported an impairment of concurrent training on
performance variables development (107). Additionally, both training regimens also
showed a positive effect on body fat loss in adolescent school boys and girls. Therefore, the
present results may suggest that concurrent resistance and endurance training seems to
be an effective, well-rounded exercise program that can be prescribed as a means to
improve initial or general strength in healthy schoolboys. Moreover, both training
programs regimens effects were persisted as long as upper and lower limb strength gains
were kept during 12 weeks of detraining period. Concordantly the group submitted to
strength and endurance program did not show estimated VO2max loss in detraining
period.
In girls, for GCOM, the magnitude of decrease observed in BF was significantly greater
(-11.4%, p=0.01) than that observed in GR (-6.2%, p=0.03). However, we did not find any
change in body weight and BMI for any group. These results suggest a major positive effect
of concurrent strength and aerobic training over body fat loss occurs. This could be related
to the fact that aerobic exercise can contribute an increase on fat metabolism. In fact, it is
known that insulin sensitivity increases with aerobic training and also has an effect on
glucose transportation; insulin has an anabolic effect on fat storage in the fat cells (90).
Insulin affects appetite regulation through the change in substrates in the blood. Insulin
Overall discussion and conclusions.
83
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
sensitivity may therefore be one of the key mechanisms behind the association found
between body composition and fitness (90). Furthermore, although the design of the
training intervention of this study is different from research conducted by Watts et al.
(127), the current results are in agreement with their study results. Watts et al. (127)
examined 19 obese adolescents aged 12–16 years independent influence of 8 weeks of
combined strength and aerobic training. Here, although bodyweight and BMI has not
changed with exercise, significant improvements in central adiposity were observed
following the 8-week circuit-training programme (135). Moreover, the total body fat
decreased but the majority of fat tissue mass was lost from the abdominal and trunk areas.
Interestingly, subcutaneous (skinfold) fat measures did not change, even in these areas,
suggesting that exercise training may beneficially modify body composition, with initial
decreases in fat predominantly occurring from the viscera (135).
Contrarily to what was observed in girls, the magnitude of decrease observed in boy’s BF
was not significantly different between GR and GCOM groups. We did not find any change
in body weight for any group. It should be highlighted that body weight does not always
explains the true body composition and therefore, despite we did not find body weight
changes, we found body fat significant losses in both experimental groups. However, we
did not find significant differences between experimental groups. These results may
suggest that there is no major positive effect of concurrent resistance and endurance
training when body fat loss occurs. Furthermore, the current results are in agreement with
the research conducted by Watts et al. (127) that examined an independent influence of 8
weeks of combined strength and aerobic training in 19 obese adolescents aged 12–16 year
olds. On this, although bodyweight and BMI did not change with exercise, significant
Overall discussion and conclusions.
84
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
improvements in central adiposity were observed following the 8-week circuit-training
program (127).
Girls’ upper body strength (e.g. the medicine ball throw with 1kg and 3Kg), has
significantly increased in both GCOM and GR group. This data may suggest a positive
influence of strength training on strength performance results, no matter with or without
concurrent strength and aerobic training. Concordantly to the upper body strength results,
the power of lower limbs revealed by the CMVJ and CMSLJ performance has changed for
both experimental groups. To our knowledge, few studies have compared the effects of
different methods of organising training workouts. For example, Sale et al. (100) observed
that concurrent strength and endurance training applied on separate days produced gains
superior to those produced by concurrent training on the same day. Although the training
programs were held otherwise constant, alternate-day training was more effective in
producing maximal leg press strength gains than same-day training. This suggests that the
interference effect may also be true when the overall frequency and/or volume of training
are higher than in this particular study. Briefly, the results do not demonstrate the
universality of the interference effect in strength development when strength training is
performed concurrently with aerobic training in schoolgirls. It is difficult to compare the
results in scientific literature when studies differ markedly in their design factors
including mode, frequency, intensity, volume of training, and training history of subjects
(106;56). Therefore, further research is required to investigate these causes and identify
other possible mechanisms responsible for the observed inhibition in strength
development after concurrent training (127).
A significant increasing was observed for males’ upper limb explosive strength (e.g.
medicine ball throw with 1kg and 3kg), in both GCOM and GR groups. This data may
Overall discussion and conclusions.
85
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
suggest a positive main effect of resistance training on explosive strength ability
independently of type of treatment performed. In accordance to the upper body strength
results, the explosive power of lower limbs revealed by the CMVJ and CMSLJ performance
also increased significantly for both experimental groups. Few studies, however, have
compared the effects of different methods of organizing training workouts. Here, for
example, Sale et al. (100) could observe that concurrent resistance and endurance training
applied on separate days produced superior gains to those produced by concurrent
training on the same day. Although the training programs were held otherwise constant,
alternate-day training was more efficient in producing maximal leg press strength gains
than same-day training. This suggests that the interference effect may also be true when
the overall frequency and/or volume of training are higher than in this particular study.
Also Ingle et al. (55) using a combination of resistance training and plyometric program,
found the experimental group saw a small improvement in performance over the training
intervention period. Our results also demonstrated that the endurance training does not
positively affect strength development in school boys. In addition, however, the present
research showed that concurrent resistance and endurance training does not impair
strength development.
Unfortunately, it is difficult to compare results in the scientific literature when studies
differ markedly in their design factors including load characteristics, context, equipment,
scheduling of training sessions and training history of subjects (70,124). Therefore, further
research is required to investigate these causes and identify other possible mechanisms
responsible for the observed inhibition in strength development after concurrent training
(100).
Overall discussion and conclusions.
86
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Running speed increased significantly in all experimental female groups. These results
seem to indicate that additional endurance training doesn't have an additional effect over
strength training to enhance running speed in young girls. On the other hand, all students
took part in various sports during Physical Education classes. Although physical education
intensity can be considered low to moderate, some sports (for instance, soccer and
basketball) bring high intensity performances (sprints) and low-intensity periods, which
could have enhanced running speed performance.
Boys’ running speed increased significantly in all experimental groups. In agreement with
previous studies (78), these results seem to indicate that additional endurance training
has not an additional effect over strength training to enhance running speed in young
boys. On the other hand, all students approached various sports during Physical
Education classes. Although physical activity intensity can be considered low to moderate,
some sports (for instance, soccer and basketball) elicit high intensity performances
(sprints) and low-intensity periods, which could have enhanced running speed
performance.
Many people rationalise that concurrent training will give them the benefits of both
strength and endurance training (1). The fact that an inhibition in strength or endurance
adaptation as a consequence of concurrent training has been reported (124). The present
study, however, could observe a significant enhancement in girls’ VO2max (ml.kg-1.min-1)
for both GC and GCOM, suggesting that the endurance training program component was
effective to a rising in aerobic fitness independently of the treatment group. Our data
suggest that dependent variable selection can influence conclusions made with respect to
changes in strength and endurance as a result of concurrent training. However, differences
in the design of concurrent training interventions, such as mode, duration, and intensity of
Overall discussion and conclusions.
87
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
training, may influence whether any interference in strength or endurance development is
observed. Clearly, the interaction between strength and endurance training is a complex
issue, and it may still be possible to design specific concurrent training regimens that can
minimize or possibly avoid any interference effects.
We could observe a significant enhancement in boys’ VO2max (ml.kg-1.min-1) only for
GCOM, suggesting that the resistance training program component was not effective to a
rising in aerobic fitness for young school boys. Our data suggest that dependent variable
selection can influence conclusions made with respect to changes in strength and
endurance as a result of concurrent training. However, differences in the design of
concurrent training interventions, such as mode, duration, and intensity of training, may
influence whether any interference in strength or endurance development is observed.
Clearly, the interaction between strength and endurance training is a complex issue, and it
may still be possible to design specific concurrent training regimens that can minimize or
possibly avoid any interference effects.
Detraining effects
To our best knowledge, no other study has established the effect of an 8-week school
based endurance and strength training program and detraining on dynamic muscular
power and body composition in adolescent girls, performed additionally to the physical
education lessons. Thus, it is difficult to compare the present results with other studies
that have investigated physical training cessation because they differ markedly in a
number of factors, including the sample and the method of measurement.
The detraining period was coincided with the summer holidays: 12 consecutive weeks.
Thus, sample subjects had no formal physical activity (Physical Education lessons or
institutional training programs) during this period. Despite that physical activity had
Overall discussion and conclusions.
88
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
decreased in an overall view, all female groups kept body composition. Only the GCOM
increased significantly in body weight (+1.6%) but not BF. Additionally, the biggest BF
percentage loss was noticed in GCOM during the intervention period. Therefore, we can
assume that the sustainment of BF obtained within the training programs participation is
visible for several weeks after the programme has finished.
Conversely to girls’ GCOM, Boy’s GCOM significantly decreased body weight (-1.7%,
p=0.03). In Total Standing Height variable, both males’ experimental groups had a
significant increase from post-training to detraining moment. There was no significant
difference in BMI on GR group from post-training to detraining moment. Additionally,
there was no significant difference in BF percentage loss between GR and GCOM during the
intervention period. Thus, we can assume that the sustainment of BF obtained with
training programs participation is visible for several weeks after the programme has
finished.
Regarding to CMVJ, all females’ groups had shown a significant loss of performance trend
(p<0.02). However, in CMSLJ only female GCOM had significantly reduced (p=0.00)
performance during the detraining recess. This decrement was not surprising since GCOM
had a higher increase (however not significantly different from GR) during the training
period. Conversely to post-training moment, all boys’ groups had shown no significant
loss performance on CMVJ and CMSLJ.
In females’ speed running a significant loss of performance was found in GC and GCOM, but
not in GR. This loss was expected as speed running is strongly affected by the nervous
system adaptation and phosphocreatine reserves. In boys’ speed running a significant loss
performance was expected but it was not found in both GR and GCOM.
Overall discussion and conclusions.
89
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
In girls, for 1 and 3Kg medicine ball throw distance test, no significant changes were
observed for the experimental groups, despite an overall increase in performance, which
means a more sustained effect of training in this power task. The control group had the
worst performance marks for both the 1 and 3Kg medicine ball throw distance test. Yet,
only the 3kg medicine ball throw distance test, change was significant. For both variables,
differences were found between GC and GR as well as between GC and GCOM. Thus, power
strength gains from both training programs were kept after a DT period of 12 weeks, as
strength is determined, among other factors, by muscular mass. Faigenbaum et al. (41)
results show that the 8 weeks of detraining led to significant losses of leg extension (-28.1
%) and chest press (-19.3%) strength whereas the control group strength scores remained
relatively similar.
In males’ sample the 1 and 3 kg medicine ball throw distance test, no significant changes
were observed for experimental groups, which mean a sustained effect of training in this
explosive task. Our results are in disagreement with Ingle et al findings (55), which in a
detraining 12-week period the experimental group saw reductions for all of the resistance
exercises that ranged from -16.3 to -30.3%. Control group had also no differences in
performance marks for both 1 and 3Kg medicine ball throw distance test. Therefore, it
must be suggested that explosive strength gains induced by both training programs were
kept after a DT period of 12 weeks, as strength is determined, among other factors, by
muscular mass. Faigenbaum et al. (41) showed that 8 weeks of detraining led to significant
losses of leg extension (-28.1%) and chest press (-19.3%) strength whereas control group
strength scores remained relatively unremarkable.
Finally, the girls’ VO2max (ml.kg-1.min-1) remained stable for all groups, except for GCOM
where a significant loss (-4.3%) was observed. Mujika & Padilla (83) found that changes
Overall discussion and conclusions.
90
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
are more controlled in recently trained subjects (compared with highly trained subjects)
in the short-term, but recently acquired VO2max gains are completely lost after training
ceases for longer than 4 wks. Conversely, our results show that GCOM kept VO2max gains
even after 12 wks of DT.
Boys’ VO2max (ml.kg-1.min-1) remained stable for GCOM, except for GR where a
significantly loss (-6.8%) was observed. Another study (107) found that changes are more
moderate in recently trained subjects (compared with highly trained subjects) in the
short-term, but recently acquired VO2max gains are completely lost after training
stoppage periods longer than 4 weeks. Conversely, ours results show that boys’ GCOM
kept VO2max gains even after 12 weeks of DT. The detraining effect over VO2max has been
poorly studied in non-adult and non-sportive samples. Hence, due to the males’ small
sample size and the lack of a pre-study power analysis to determine adequate effect size
for this study, we suggest that our subgroup analyses and results must be interpreted with
caution.
Veracity of formulated hypotheses
The Hypothesis 1 “school-based strength training is really effective on adolescent subjects
for both genders” was confirmed. The Hypothesis 2 “when trained alone, strength training
does not produce significant higher muscular strength increases in boys when compared
with results obtained after concurrent resistance and endurance training” and the
Hypothesis 3 “when trained alone, strength training does not produce significant higher
muscular power increases in girls when compared with results obtained after concurrent
strength and aerobic training were also confirmed. The Hypothesis 4 “when trained alone,
strength training does not produce significant higher body composition improvements in
Overall discussion and conclusions.
91
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
boys when compared with results obtained after concurrent resistance and endurance
training” was partially confirmed. Nevertheless, the Hypothesis 5 “when trained alone,
strength training does not produce significant higher body composition improvements in
girls when compared with results obtained after concurrent resistance and aerobic
training” was totally confirmed. The Hypothesis 6 “concurrent resistance and aerobic
training does not impair strength improvements in boys” and the Hypothesis 7
“concurrent strength and aerobic training does not impair endurance improvements in
girls” were also confirmed. The Hypothesis 8 “Regarding concurrent training it is possible
to observe improvements in both genders, and regarding to detraining both genders would
keep improvements acquired during training process”, the Hypothesis 9 “in boys, twelve
weeks of detraining period are not sufficient to loss all training improvements resulted
from training program” and the Hypothesis 10 “In girls, twelve weeks of detraining
period are not sufficient to loss all training improvements resulted from training program”
were partially confirmed.
Overall discussion and conclusions.
92
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Conclusions of the five studies
Study 1
Comparing with untrained youth, their trained counterparts had a higher aerobic
performance in ergometers’ tests, and this reached significance in pubertal and post-
pubertal girls. There is no consensus regarding to VO2max related gender improvements
differences in pre- and early pubescent subjects. In adolescent, it seems that male increase
aerobic capacity more than their age-counterparts.
When we considered the studies which have investigated strength training alone, we
found that prepubescent to early post-pubescent boys and girls who participate in a
resistance training programme can significantly raise upper and lower body strength
performance, enhance flexibility and improve body composition as well. Different training
modes are effective on strength training development of both trained and untrained or
pre- and pubescent boys and girls. Moreover, performing resistance training a minimum of
10-15 minutes twice a week, at a moderate volume is more effective and efficient than
performing at a higher volume.
Concurrent strength and aerobic training seems to be effective in pre-pubescent and post
pubescent boys and girls. It can be assumed that concurrent strength and endurance
training not only does not impair strength nor aerobic development as seems to be an
effective, well-rounded exercise program that can be used as a means to improve initial or
general strength in youth.
At last, studies that have been properly investigated the changes in resistance training-
induced strength gains during detraining in pre adolescents are still scarce and
Overall discussion and conclusions.
93
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
insufficient. Different results have been found on detraining effect over subject’s strength
gains.
Study 2
Concurrent strength and aerobic school-based training program seems considerably
effective on both strength and aerobic fitness feature of age-school boys. However, the
strength-training program also produced identical results on strength development.
Therefore, performing simultaneously resistance and endurance training in the same
workout not only does not impair strength development in healthy school boys but also
seems to be an effective, well-rounded exercise program that can be prescribed as a means
to improve initial or general strength.
Study 3
Concurrent strength and aerobic school-based training programs seem to be more
effective on both power strength and aerobic fitness feature of age-school girls. In
agreement with the conclusion of study two, performing simultaneously strength and
endurance training in the same workout does not impair strength development in young
girls.
Study 4
Boys’ training program effects persists even at the end of 12-wks detraining period. Those
effects include body composition improvements, and physical fitness components as
muscular power and aerobic fitness.
Study 5
Detraining period was not sufficient to reduce the overall training effects on girls’ body
composition and performance variables.
Overall discussion and conclusions.
94
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Overall Conclusion
Our results suggest that a concurrent strength and endurance school-based training
program seems considerably effective on both strength and endurance fitness feature of
age-school youth. In other words, our study indicates that concurrent training is an
effective, well-rounded exercise program that can be set up as a means to improve initial
or general strength in healthy school non-adult population. Moreover, performing
simultaneously strength and endurance training in the same workout does not impair
strength development in young subjects, which has important practical relevance for the
construction of strength training in school-based programs. In other words, the present
study indicates that concurrent training is an effective, well-rounded exercise program
that can be performed to improve initial or general strength in healthy school subjects.
Our results also suggest that training program effects persists even at the end of detraining
period. Those effects include body composition effects, and physical fitness components as
strength and endurance. Future researches should examine the interference effects arising
from the order of resistance and endurance training exercises program on strength
enhancement.
Practical Applications
Performing simultaneously resistance and endurance training in the same workout not
only does not impair strength development in healthy school children and adolescent but
also seems to be an effective, well-rounded exercise program that can be prescribed as a
means to improve initial or general strength. That should be considered in designing of
strength training school-based programs in order to improve its efficiency. Furthermore,
Overall discussion and conclusions.
95
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
school-based programs should be implemented since training program effects persists at
the end of summer holidays on body composition and physical fitness level.
References
96
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
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Appendices
a
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Appendices
Appendix A
Journal of Human Kinetics Special Issue 2011, 93‐103 93
1‐ Department of Sport Sciences, University of Beira Interior (UBI), Covilhã, Portugal 2 ‐ Research Centre for Sport Sciences, Health and Human Development, Vila Real, Portugal 3‐ Department of Health Sciences, Public University of Navarre, Navarre, Spain
Authors submitted their contribution of the article to the editorial board.
Accepted for printing in Journal of Human Kinetics Special Issue 2011 on September 2011.
The Effects of Concurrent Resistance and Endurance Training
Follow a Specific Detraining Cycle in Young School Girls
by
Albano Santos1,2, Daniel A. Marinho1,2, Aldo M. Costa1,2, Mikel Izquierdo3,
Mário C. Marques1,2
The purpose of this study was to compare the effects of an 8‐week training period of strength training alone
(GR), or combined strength and endurance training (GCOM), followed by 12‐weeks of de‐training (DT) on body
composition, power strength and VO2max adaptations in a schooled group of adolescent girls. Methods: Sixty‐seven
healthy girls recruited from a Portuguese public high school (age: 13.5+1.03 years, from 7th and 9th grade) were divided
into three experimental groups to train twice a week for 8 wks: GR (n=21), GCOM (n=25) and a control group (GC:
n=21; no training program). Anthropometric parameters variables as well as performance variables (strength and
aerobic fitness) were assessed. Results: No significant training‐induced differences were observed in 1kg and 3kg
medicine ball throw gains (2.7 to 10.8%) between GR and GCOM groups, whereas no significant changes were
observed after a DT period in any of the experimental groups. Significant training‐induced gains in CMVJ (8 to 12%)
and CMSLJ (0.8 to 5.4%) were observed in the experimental groups. Time of 20m significantly decreased (GR: ‐11.5%
and GCOM: ‐10%) after both treatment periods, whereas only the GR group kept the running speed after a DT period
of 12 weeks. After training VO2max increased only slightly for GCOM (4.0%). No significant changes were observed
after the DT period in all groups, except to GCOM in CMVJ and CMSLJ. Conclusion: Performing simultaneous
strength and endurance training in the same workout does not appear to negatively influence power strength and
aerobic fitness development in adolescent girls. Indeed, concurrent strength and endurance training seems to be an
effective, well‐rounded exercise program that can be prescribed as a means to improve initial or general strength in
healthy school girls. De‐training period was not sufficient to reduce the overall training effects.
Key words: Youth, Strength, Endurance, School, Experimental, weight training, detraining
Introduction
Strength training is defined as a
specialized method of conditioning that involves
the progressive use of a wide range of resistive
loads and a variety of training modes (e.g., free
weights, weight machines, elastic cords, medicine
balls, and body weight) designed to enhance
health, fitness and sports performance (0).
Scientific evidence indicates that strength training
should be part of a comprehensive health
maintenance (Faigenbaum, 2007) and physical
performance (Anderson and
Haraldsdottir, 1995) effective strategy for youth,
as long as it is carefully prescribed and monitored
(Simons‐Morton et al., 1993; Sharma, 2006;
Izquierdo et al., 2010). Further, female
participation in sport has increased dramatically
over the previous 20 years in a variety of events.
However, despite the increase in female physical
activity (PA) regular programs, there is a paucity
of research on performance characteristics of
female adolescents and to the authors’ knowledge
few data are available for young school girls
94 Concurrent strength and endurance training/de‐training in high school
Journal of Human Kinetics Special Issue 2011, http://www.johk.pl
(Sweeting, 2007; Faigenbaum et al., 2009).
School girls have been described as less
active than their male age‐peers (Nielsen and
Andersen, 2003; Faigenbaum, 2007) and become
even less physically active as they are going
through adolescence (Twisk et al., 2000; Sweeting,
2007). Nevertheless, it was reported by several
studies that physical activity levels of children
aged 13 to 15 years old are positively related with
physical fitness (Malina, 2001). Moreover, there is
strong evidence that school‐based interventions
are effective to promote PA levels (Faigenbaum et
al., 1996; Strong et al., 2005; Sweeting, 2007) and,
therefore, school seems to provide an excellent
setting to enhance its levels by implementing
physical fitness programs.
Both strength and endurance training are
often performed concurrently in most exercise
programs in wellness, fitness and rehabilitative
settings, in an attempt to reach different physical
fitness goals (Anderson and Haraldsdottir, 1995).
Several studies using young adult sample, have
shown that simultaneously performing strength
and cardiovascular training, the strength gains
achieved by strength training alone may be
impaired (Kraemer et al., 1995). Unfortunately,
few authors have examined the effects of
concurrent strength and endurance training on
different days (Sale et al., 1990), on the same day
(Abernethy and Quigley, 1993; Volpe et al., 1993)
or a compound of both methods (Hunter et al.,
1987). Researches in a school environment,
concerning this issue, are even scarcer (Izquierdo
et al., 2010). Moreover, to our best knowledge, no
study prior to ours had studied the effects of
power training with concurrent power and
endurance training on muscular strength
development in a large sample of non‐athlete
adolescent girls.
Physical activity interruption because of
illness, injury, holidays, or post‐season break
occurring through life or other factors are normal
situations in any kind of sport (0; Garrido et al.,
20100). The magnitude of this reduction may
depend upon the length of the detraining period
in addition to training levels attained by the
subject (0). However, the detraining period and its
consequences are not well reported in sports
literature during puberty. Additionally, a period
of strength training cessation can also produce a
positive delay transformation to enhanced sports
specific performance (0). In fact, it has been shown
that physical fitness improves during the school
year (yr), with little or no changes during the
summer holidays (0). Another study (0) could
observed that girls can significantly reduce
cardiorespiratory fitness after the holiday period.
However, the detraining period and its
consequences are not well reported in the
scientific community, or within a group of school
girls (0; 0). Furthermore, the effects of training
may not manifest soon after the training but may
appear later.
According to the above mentioned, we
hypothesized that concurrent strength and
endurance training would have a bigger positive
effect on muscular strength development of un‐
trained school girls compared with the results
found when strength was trained alone. We also
hypothesized that both strength training and
concurrent strength and endurance training
groups would keep some strength gains after a
training break. Therefore, the main purpose of the
current study was twofold: (i) to analyze the
effects of strength training alone, or combined
strength and endurance training on body
composition, strength and cardiovascular markers
on a sample of healthy schoolgirls and, (ii) to
assess the effects of a de‐training period on
strength and endurance performance.
Methods
Experimental design
Sixty‐seven healthy girls (13.5±1.03 years
old) recruited from a Portuguese public high
school were divided into two experimental
groups (to train 2 times per week for 8 weeks) and
one control group as follows: one group
performing strength training only (GR: n=21);
another group performing combined strength and
endurance training (GCOM: n=25); an additional
group as control (GC: n=21; without training
program). All subjects attended physical
education classes twice a week, with a duration of
45 min and 90 min each class respectively. In
these classes, students took part in various sports
(gymnastics drills, soccer, basketball and
volleyball) with a clear pedagogical focus. As
such, according to other researchers (Simons‐
Morton et al., 1993; Silva et al., 2010) the physical
activity intensity is considered low to moderate.
by Santos A. et al. 95
© Editorial Committee of Journal of Human Kinetics
Participants in all groups were asked to maintain
normal eating and physical activity patterns over
the duration of the study. This procedure was the
same as Lubans et al. (2010).
Table 1
Design of the training program performed
Exercises Session 1 Session 2 Session 3 Session 4 Session 5 Session 6
Chest 1 kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8 6x8 6x8
Chest 3 kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8
Overhead 1kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8 6x8 6x8
Overhead 3kg Medicine Ball Throw 1,2 2x8 2x8 2x8 2x8
CMJ onto a box 1,2 1x5 1x5 3x5 3x5 3x5 4x5
Plyometric Jumps above 3 hurdling1,2 5x4 5x4 5x4 5x4 2x3 2x3
Sprint Running (m)1,2 4x20m 4x20m 3x20m 3x20m 3x20m 3x20m
20m Shuttle Run (MAV)2 75% 75% 75% 75% 75% 75%
Exercises Session 7 Session 8 Session 9 Session
10
Session
11
Session
12
Chest 1 kg Medicine Ball Throw 1,2
Chest 3 kg Medicine Ball Throw 1,2 2x5 2x5 3x5 3x5 3x5 2x5
Overhead 1kg Medicine Ball Throw 1,2
Overhead 3kg Medicine Ball Throw 1,2 2x8 2x8 3x8 3x8 3x8
CMJ onto a box 1,2 4x5 5x5 5x5 5x5 5x5 4x5
Plyometric Jumps above 3 hurdling1,2 3x3 4x3 4x3 4x3 4x3
Sprint Running (m)1,2 4x30m 4x30m 4x30m 4x30m 4x30m 3x40m
20m Shuttle Run (MAV)2 75% TestM 75% 75% 75% 75%
Exercises Session 13 Session
14
Session
15
Session
16
Chest 1 kg Medicine Ball Throw 1,2
Chest 3 kg Medicine Ball Throw 1,2 2x5 1x5
Overhead 1kg Medicine Ball Throw 1,2 3x8 2x8 2x8
Overhead 3kg Medicine Ball Throw 1,2 3x8
CMJ onto a box 1,2 4x5 2x5 2x4 2x4
Plyometric Jumps above 3 hurdling1,2 4x3 3x3
Sprint Running (m)1,2 3x40m 4x40m 2x30m 2x30m
20m Shuttle Run (MAV)2 75% 75% 75% 75%
For the Medicine Ball Throwing and Jump onto box the 1st no. corresponds to sets and 2nd corresponds to repetitions.
For Sprint Running 1st number corresponds to sets and 2nd corresponds to the distance to run.
For 20m Shuttle Run training each girl ran each session (until testM) 75% of maximum individual
aerobic volume performed on pre‐test and after this testM moment until program end,
ran 75% of maximum individual aerobic volume performed on testM. CMJ – Counter movement jump.
MAV ‐ maximum individual aerobic volume 1=power strength training protocol (GR).
2=concurrent resistance and endurance training (GCOM).
96 Concurrent strength and endurance training/de‐training in high school
Journal of Human Kinetics Special Issue 2011, http://www.johk.pl
Beyond to physical education classes, and
after a 10 min warm up period (7 min running
with an intensity sufficient to raise breath rate, 3
min stretching and joint specific warm up), both
experimental groups were submitted to a strength
training program composed by: 1 and 3 kg
medicine ball throws; jumps onto a box (from 0.4
m to 0.6 m); plyometric jumps above 0.4‐0.6 m of
height hurdle and; sets of 30 to 40m speed
running. The GCOM group was further subjected
to a 20m shuttle run exercise (0).
This endurance task, which occurred
immediately after the strength training session,
was developed based on an individual training
volume ‐ set to about 75% of the established
maximum aerobic volume achieved on a previous
test.
After 4 weeks of training, GCOM subjects
were reassessed using 20m shuttle run tests in
order to readjust the volume and intensity of the
20m shuttle run exercise. All participants were
familiarised with power training tests (sprints,
jumps and ball throws) as well as with the 20m
shuttle run test. A more detailed analysis of the
program can be found in table 1.
All sample groups were assessed for
upper and lower body power strength (overhead
medicine ball throwing and counter movement
vertical jump, respectively), running speed (20 m
sprint run) and VO2max estimate (20 meters
shuttle run test) before and after 8‐weeks of
training.
In order to evaluate the DT effects, all
individuals were reassessed 12 weeks after
training has ceased. The DT period was
coincidental with summer holidays. Throughout
this period, the subjects reported their non‐
involvement in regular exercise programs for
developing or maintaining strength and
endurance performance. The testing assessment
procedures were always conducted in the same
indoor facility, at the same hour and on the same
weekday (from March to September of 2010). Data
collection was performed by the same investigator
and after a general warm‐up of 10 minutes.
Subjects
A sample of 67 healthy girls recruited
from a Portuguese public high school (from 7th
and 9th grades) was used in this study. To fulfill
the ethical procedures of the Helsinki statement
(WMA Declaration of Helsinki, 2008), a consent
form was obtained prior to all the testing from
parents or a legal guardian of the adolescents.
Efforts were made to pick subjects for making
comparable groups. Maturity level based on
Tanner stages (Duke et al., 1980) was self‐
assessed. Students were asked to answer to an
image with corresponding legend questionnaire.
Students answered the questionnaire in an
individual booth without interference from their
teachers or school friends. There were no
significant differences (p>0.05) between groups
for age or Tanner stages, neither in strength or
endurance fitness performances at the beginning
of the protocol. No subject had regularly
participated in any form of strength training
program prior to this experiment. The following
exclusion criteria were used: subjects with a
chronic paediatric disease or with an orthopaedic
limitation.
Anthropometrical Variables
Total height (m) was assessed according
to international standards for anthropometric
assessment (0), with a Seca 264 Stadiometer
(Hamburg, Deutschland). Weight and body fat
were assessed using a Tanita body composition
analyser; model TBF‐300 (Tanita Corporation of
America, Inc, Arlington Heights, IL) with a range
of ratio 1%‐75%. These two parameters were
assessed prior to any physical performance test.
Subjects were measured wearing shorts and t‐
shirts (shoes and socks were asked to be
removed).
Overhead Medicine Ball Throwing
An overhead medicine ball throw was
used to evaluate the upper body ability to
generate muscular actions at a high rate of speed.
Prior to baseline tests, each subject underwent one
familiarization session and was counselled on
proper overhead throwing with different
weighted balls. Pre‐tests, post‐tests and de‐
training measurements were taken on maximal
throwing velocity using medicine balls weighing
1kg (perimeter 0.72m) and 3kg (perimeter 0.78m).
A general warm‐up period of 10 minutes, which
included throwing the different weighted balls,
was allowed. While standing, subjects held
medicine balls with 1 and 3kg in both hands in
front of the body with arms relaxed. The students
were instructed to throw the ball over their heads
as far as possible. A counter movement was
by Santos A. et al. 97
© Editorial Committee of Journal of Human Kinetics
allowed during the action. Five trials were
performed with a one‐minute rest between each
trial. Only the best throw was used for analysis.
The ball throwing distance (BTd) was recorded to
the closest cm as proposed by van Den Tillaar &
Marques (2009). This was possible as polyvinyl
chloride medicine balls were used and when they
fall on the Copolymer Polypropylene floor they
make a visible mark. The ICC of data for 1kg and
3 kg medicine ball throwing was 0.94 and 0.93,
respectively.
Counter Movement Vertical Jump (CMVJ)
The standing vertical jump is a popular
test of leg power and is routinely used to monitor
the effectiveness of an athleteʹs conditioning
program. The students were asked to perform a
counter movement jump (with hands on pelvic
girth) for maximum height. The jumper starts
from an upright standing position, making a
preliminary downward movement by flexing at
the knees and hips; then immediately extends the
knees and hips again to jump vertically up off the
ground. Such movement makes use of the stretch‐
shorten cycle, where the muscles are pre‐stretched
before shortening in the desired direction (0). It
was considered only the best performance from
the three jump attempts allowed. The counter
movement vertical jump has shown an ICC of
0.89.
Counter Movement Standing Long Jump (CMSLJ)
Each participant completed three trials
with a 1‐min recovery between trials using a
standardised jumping protocol to reduce inter‐
individual variability. From a standing position,
with the feet shoulder‐width apart and the hands
placed on the pelvic girth, the girls produced a
counter movement with the legs before jumping
horizontally as far as possible. The greatest
distance (meters) of the two jumps was taken as
the test score, measured from the heel of the rear
foot. A fiber‐glass tape measure (Vinex, MST‐50M,
Meerut, India) was extended across the floor and
used to measure the horizontal distance. The
counter movement standing long jump has shown
an ICC of 0.96.
Sprint Running
The time to run 20m was obtained using a
Brower Timing System (Utah, USA). At the start
each subject trod the cell pad. The time to run the
distance was recorded using a digital and
automatic chronometer commanded by the cell
pad and a pair of photocells positioned above the
20m line. All subjects were encouraged to run as
fast as possible and to decelerate only after
listening to the beep emitted by the last photocells
pair. Each student repeated the same procedure
for 3 attempts and only the best time reached was
recorded. The sprint running (time) has shown an
ICC of 0.85.
20 Meter Shuttle Run (VO2max)
This test involves continuous running
between two lines (20m apart in time) to recorded
beeps. The time between recorded beeps
decreases each minute (level). We chose to use the
common version that has an initial running
velocity of 8.5 km/h, which increases by 0.5 km/h
each minute (0). The final students score was
based on the level and number of shuttles reached
before they were unable to keep up with the
audio recording. Estimated VO2max (ml.kg‐1.min‐1)
was calculated by the Légerʹs equation (0). The
20m Shuttle Run test has shown an ICC of 0.91.
Statistical analyses
Standard statistical methods were used
for the calculation of the means and standard
deviations (SD). One‐way analysis of variance
(ANOVA) was used to determine any differences
among the three groups’ initial strength,
endurance, running speed and anthropometry.
The training related effects were assessed using a
two‐way ANOVA with repeated measures
(groups x moment). Selected absolute changes
were analyzed via one‐way ANOVA. The p ≤ 0.05
criterion was used for establishing statistical
significance.
Results
At baseline, no significant differences
were observed between groups for any of the pre‐
training anthropometrics and performance
variables (p>0.05). Body fat (BF) significantly
decreased (p<0.01) from the pre‐training to the
post‐training period in all groups (Table 2). No
significant changes were observed for height,
body weight and body mass index (BMI) in any of
the groups. Only GCOM increased significantly
1kg and 3kg ball throw distance (p<0.05). GR
increased significantly 3kg ball throw distance
(p<0.05) (Table 3). The CMVJ height remained
stable after the training program for group GR
98 Concurrent strength and endurance training/de‐training in high school
Journal of Human Kinetics Special Issue 2011, http://www.johk.pl
(0%; ns) whereas GR (+8%; 0.01) and GCOM
(+12%; 0.00) significantly increased CMVJ height
after the training program. Both experimental
groups also increased their performance in CMSLJ
after the training program: GR (+0.8%; 0.04) and
GCOM (+5.4%; 0.01). GC (‐2.3%; ns) didn’t change
significantly CMSLJ height in the same period.
The time to run 20m significantly decreased in GR
(‐11.5%, p=0.00) and GCOM (‐10%, p=0.00),
whereas remained constant in GC. The amount of
changes was similar in both GR and GCOM
groups. Finally, the VO2max increased
significantly in both GC (+3.2%, p<0.05) and
GCOM (+4.0%, p<0.01), whereas it remained
unchanged in GR group.
The detraining period resulted in an
increase in body weight (+1.6%, p<0.04) for
GCOM (Table 3), whereas remained constant for
the GR and GC groups. Body height increased
significantly for GR (+0.2%, p<0.03).
This endurance task, which occurred
immediately after the strength training session,
was developed based on an individual training
volume ‐ set to about 75% of the established
maximum aerobic volume achieved on a previous
test.
No significant changes were observed in
the 1kg and 3kg medicine ball throw gains after
the DT period in any of the experimental groups
(Table 3). Additionally, table 3 shows that all
groups had significantly lower scores in the
vertical jump height after DT period: less 23.1%
for GC (p=0.00), less 3.7% for GR (p=0.02) and less
14.3% for GCOM (p=0.00). Significant differences
were found between GC and GR as well as
between GR and GCOM groups. Both GC (+1.6%;
ns) and GR (‐3.8%; ns) didn’t change their CMSLJ
performance after the de‐training period.
However, GCOM (‐4.4%; 0.00) has reduced
CMSLJ height in the same period. The time to run
20m decreased in GC and GCOM (1.2% and 1.9%,
respectively), yet no significant differences
between groups were observed after DT.
Estimated VO2max remained unchanged after DT
period in all groups.
Table 2
Descriptive (mean ± standard deviation) characteristics of the participants during three testing trials
(M1, M2 and M3) for all groups
Variable Group M1 M2 M3 (M1‐M2) (M2‐M3)
х± х± х±
Body Weight (kg)
GC 51,5±11,1 53,9±12,7 51,9±12,2 0,39 0,99
GR 58,9±13,5 59,0±14,1 60,4±15,4 0,95 0,56
GCOM 54,8±17,1 54,5±18,0 55,2±18,3 0,64 0,04
Total Standing Height
(cm) GC 156,8±6,5 158,3±6,9 158,9±6,9 0,06 0,34
GR 159,4±6,1 159,4±6,0 160,2±6,3 0,14 0,03
GCOM 157,9±8,2 158,0±7,8 158,2±7,9 0,79 0,07
BMI (kg.m‐2)
GC 20,9±4,0 21,6±4,7 20,9±4,9 0,68 0,65
GR 23,0±4,1 23,0±4,5 23,2±5,4 0,35 0,62
GCOM 21,6±5,3 21,6±5,4 21,8±5,6 0,24 0,12
Body Fat (%)
GC 24,34±6,5 24,29±7,8₮ 22,42±8,8 0,01 0,79
GR 32,14±7,7 30,16±8,2 31,53±8,6₮ 0,00 0,3
GCOM 26,79±9,9 24,23±10,4¥ 25,34±11,1 0,00 0,3
х – mean; ‐ standard deviation; M1 – before training program; M2 – After training program; M3 – After detraining period; p(M1‐M2)‐ p value for comparison between 2nd and 1st moment,
p(M2‐M3) ‐ p value for comparison between 3th and 2nd moment; GC – Control Group,
GR – resistance training group, GCOM ‐ concurrent resistance and endurance training,
₮ ‐ Significant changes between GC and GR; ‡ ‐ Significant changes between GC and GCOM; ¥ ‐ Significant changes between GR and GCOM.
by Santos A. et al. 99
© Editorial Committee of Journal of Human Kinetics
Discussion Training period
The primary findings of the study showed
that concurrent strength and cardiovascular
training may be a positive training stimulus to
induce power strength and aerobic fitness
development and also showed an extremely
positive effect on body fat loss in adolescent
school girls. Therefore, the present results may
suggest that concurrent strength and endurance
training seems to be an effective, well‐rounded
exercise program that can be used as a means to
improve initial or general strength in healthy
school girls.
In GCOM, the magnitude of decrease
observed in BF was significantly greater (‐11.4%,
p=0.01) than that observed in GR (‐6.2%; p=0.03).
However, we did not find any change in body
weight and BMI for any group. These results
suggest a major positive effect of concurrent
strength and endurance training over body fat
loss occurs. This could be related to the fact that
aerobic exercise can contribute an increase on fat
metabolism. In fact, it is known that insulin
sensitivity increases with aerobic training and also
has an effect on glucose transportation; insulin
has an anabolic effect on fat storage in the fat cells
(Nielsen and Andersen, 2003).
Table 3
Mean ± standard deviation of CMVJ, CMSLJ, 1 and 3kg Medicine Ball Throwing,
Running Speed and VO2Max at all three testing trials (M1, M2 and M3) for each group
Variable
Group M1 M2 M3
х± х± х± (M1‐M2) (M2‐M3)
1Kg Medicine ball
throwing (m) GC 5,91±0,83 5,76±0,57 5,57±0,52 0,29 0,23
GR 6,43±1,26 6,80±1,34₮ 6,73±1,18₮ 0,08 0,06
GCOM 6,14±1,00 6,67±1,16‡ 6,69±1,18‡ 0,00 0,78
3Kg Medicine ball
throwing (m) GC 3,79±0,50 3,76±0,43 3,59±0,50 0,37 0,03
GR 3,93±0,73 4,29±0,74₮ 4,67±1,34₮ 0,01 0,23
GCOM 3,89±0,64 4,25±0,73‡ 4,25±0,74‡ 0,00 0,49
CM Vertical Jump (cm) GC 0,26±0,07 0,26±0,06 0,20±0,04 0,13 0,02
GR 0,25±0,06 0,27±0,07 0,26±0,06₮ 0,01 0,02
GCOM 0,25±0,06 0,28±0,08 0,24±0,06‡ 0,00 0,00
CM Standing Long Jump
(m) GC 1,32±0,23 1,29±0,20 1,31±0,31 0,17 0,50
GR 1,31±0,24 1, 32±0,26 1,27±0,29 0,04 0,23
GCOM 1,30±0,26 1,37±0,22 1,31±0,30 0,01 0,05
Running Speed 20m (s) GC 4,42±0,44 4,20±0,36 4,25±0,36 0,10 0,03
GR 4,91±0,57 4,28±0,38 4,32±0,40 0,00 0,86
GCOM 4,80±0,53 4,25±0,34 4,33±0,39 0,00 0,00
VO2Max (mL.kg‐1.min‐1) GC 40,8±4,05 41,0±4,27 45,0±8,20 0,05 0,21
GR 39,2±4,29 40,7±3,98 42,0±6,84 0,13 0,58
GCOM 42,5±4,37 43,7±4,09‡¥ 41,9±5,80 0,01 0,43
х – mean; ‐ standard deviation; CM – counter movement; M1 – before training program; M2 – After training program; M3 – After detraining period;
p (M1‐M2) ‐ p value for comparison between 2nd and 1st moment,
p (M2‐M3) ‐ p value for comparison between 3th and 2nd moment;
GC – Control Group, GR – resistance training group,
GCOM ‐ concurrent resistance and endurance training,
₮ ‐ Significant changes between GC and GR; ‡ ‐ Significant changes between GC and GCOM;
¥ ‐ Significant changes between GR and GCOM.
100 Concurrent strength and endurance training/de‐training in high school
Journal of Human Kinetics Special Issue 2011, http://www.johk.pl
Insulin affects appetite regulation
through the change in substrates in the blood.
Insulin sensitivity may therefore be one of the key
mechanisms behind the association found
between body composition and fitness (Nielsen
and Andersen, 2003). Furthermore, although the
design of the training intervention of this study is
different from research conducted by Watts et al.
(2004), the current results are in agreement with
their study results. Watts et al. (2004) examined 19
obese adolescents aged 12–16 years independent
influence of 8 weeks of combined strength and
aerobic training. Here, although bodyweight and
BMI has not changed with exercise, significant
improvements in central adiposity were observed
following the 8‐week circuit‐training programme.
Moreover, the total body fat decreased
but the majority of fat tissue mass was lost from
the abdominal and trunk areas. Interestingly,
subcutaneous (skinfold) fat measures did not
change, even in these areas, suggesting that
exercise training may beneficially modify body
composition, with initial decreases in fat
predominantly occurring from the viscera.
Upper power strength (e.g. the medicine
ball throw with 1kg and 3kg), has significantly
increased in both GCOM and GR group. This data
may suggest a positive influence of strength
training on power strength performance results,
no matter with or without concurrent strength
and endurance training. Concordantly to the
upper body strength results, the power of lower
limbs revealed by the CMVJ and CMSLJ
performance has changed for both experimental
groups. To our best knowledge, very few studies
have compared the effects of different methods of
organising training workouts. For example, Sale et
al. (1990) observed that concurrent strength and
endurance training applied on separate days
produced gains superior to those produced by
concurrent training on the same day. Although
the training programs were held otherwise
constant, alternate‐day training was more
effective in producing maximal leg press strength
gains than same‐day training. This suggests that
the interference effect may also be true when the
overall frequency and/or volume of training are
higher than in this particular study. Briefly, the
results do not demonstrate the universality of the
interference effect in strength development when
strength training is performed concurrently with
endurance training in school girls. It is difficult to
compare the results in scientific literature when
studies differ markedly in their design factors
including mode, frequency, intensity, volume of
training, and training history of subjects
(Izquierdo et al., 2010). Therefore, further research
is required to investigate these causes and identify
other possible mechanisms responsible for the
observed inhibition in strength development after
concurrent training (Watts et al., 2004).
Running speed increased significantly in
all experimental groups. These results seem to
indicate that additional endurance training does
not have an additional effect over strength
training to enhance running speed in young girls.
On the other hand, all students approached
various sports during Physical Education classes.
Although physical activity intensity can be
considered low to moderate, some sports (for
instance, soccer and basketball) elicit high
intensity performances (sprints) and low‐intensity
periods, which could have enhanced running
speed performance.
Many people rationalise that concurrent
training will give them the benefits of both
strength and endurance training (Abernethy and
Quigley, 1993). The fact that an inhibition in
strength or endurance adaptation as a
consequence of concurrent training has been
reported (Volpe et al., 1993). The present study,
however, could observe a significant
enhancement in VO2max (ml.kg‐1.min‐1) for both
GC and GCOM, suggesting that the endurance
training program component was effective to a
rising in aerobic fitness independently of the
treatment group. Our data suggest that dependent
variable selection can influence conclusions made
with respect to changes in strength and endurance
as a result of concurrent training. However,
differences in the design of concurrent training
interventions, such as mode, duration, and
intensity of training, may influence whether any
interference in strength or endurance
development is observed. Clearly, the interaction
between strength and endurance training is a
complex issue, and it may still be possible to
design specific concurrent training regimens that
can minimize or possibly avoid any interference
effects.
Detraining period
To our best knowledge, no other study
by Santos A. et al. 101
© Editorial Committee of Journal of Human Kinetics
has established the effect of an 8‐week school
based endurance and strength training program
and de‐training on dynamic muscular strength
and body composition in adolescent girls,
performed additionally to the physical education
lessons. Thus, it is difficult to compare the present
relsults with other studies that have investigated
physical training cessation because they differ
markedly in a number of factors, including the
sample and the method of measurement.
The detraining period was coincided with
the summer holidays: 12 consecutive weeks. Thus,
sample subjects had no formal physical activity
(Physical Education lessons or institutional
training programs) during this period. Despite
that physical activity had decreased in an overall
view, all groups kept body composition. Only the
GCOM increased significantly in body weight
(+1.6%) but not BF. Additionally, the biggest BF
percentage loss was noticed in GCOM during the
intervention period. Therefore, we can assume
that the sustainment of BF obtained within the
training programs participation is visible for
several weeks after the programme has finished.
Regarding to CMVJ, all groups had shown a
significant loss of performance trend (p<0.02).
However, in CMSLJ only GCOM had significantly
reduced (p=0.00) performance during the de‐
training recess. This decrement is not surprising
since GCOM had a higher increase (however not
significantly different from GR) during the
training period. In speed running a significant
loss of performance was found in GC and GCOM,
but not in GR. This loss was expected as speed
running is strongly affected by the nervous
system adaptation and phosphocreatine reserves.
In the 1 and 3kg medicine ball throw distance test,
no significant changes were observed for the
experimental groups, despite an overall increase
in performance, which means a more sustained
effect of training in this power task. The control
group had the worst performance marks for both
the 1 and 3kg medicine ball throw distance test.
Yet, only the 3kg medicine ball throw distance
test, change was significant. For both variables,
differences were found between GC and GR as
well as between GC and GCOM. Thus, power
strength gains from both training programs were
kept after a DT period of 12 weeks, as strength is
determined, among other factors, by muscular
mass. Faigenbaum et al. (1996) results show that
the 8 weeks of de‐training led to significant losses
of leg extension (‐28.1 %) and chest press (‐19.3%)
strength whereas the control group strength
scores remained relatively similar. Finally, the
VO2max (ml.kg‐1.min‐1) remained stable for all
groups, except for GCOM where a significant loss
(‐4.3%) was observed. Mujika and Padilla (2001)
found that changes are more controlled in
recently trained subjects (compared with highly
trained subjects) in the short‐term, but recently
acquired VO2max gains are completely lost after
training ceases for longer than 4 wks. Conversely,
our results show that GCOM kept VO2max gains
even after 12 wks of DT.
Overall, our results suggest that
concurrent strength and endurance school‐based
training programs seem more effective on both
strength and endurance fitness feature of age‐
school girls. In other words, our study indicates
that concurrent training is an effective, well‐
rounded exercise program that can be set up as a
means to improve initial or general strength in
healthy school girls. Moreover, performing
simultaneously strength and endurance training
in the same workout does not impair strength
development in young girls, which has important
practical relevance for the construction of strength
training in school‐based programs. The de‐
training period was not sufficient to reduce the
overall training effects. Future studies should
examine the interference effects arising from the
arrangement of strength and endurance training
exercises (e.g., endurance training before strength
training or vice versa) on strength.
Acknowledgments This study was possible thanks to Professor Jaime Sampaio (University of Trás‐os‐Montes and Alto Douro)
and Professor Hugo Louro (Rio Maior Sport High‐School – Polytechnic Institute of Santarém) for
collaborating and providing assessment equipment used in this study. We thank the children and their
parents for participating in this study and gratefully acknowledge Manuela Costeira (the School Principal of
EB Poceirão) and her management team for allowing the use of the training equipment used in this study
and school facilities, Jorge Romão (the School Principal of EB2,3 Pegões) and his management team for
allowing the use of school facilities.
102 Concurrent strength and endurance training/de‐training in high school
Journal of Human Kinetics Special Issue 2011, http://www.johk.pl
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Corresponding author
Mário C. Marques
Department of Sport Sciences, University of Beira Interior (UBI), Covilhã, Portugal. Research Centre for
Sport Sciences, Health and Human Development, Vila Real, Portugal. UBI ‐ University of Beira Interior,
Department of Sport Sciences, Rua Marquês D´Ávila e Bolama, 6200‐001 Covilhã, Portugal
Tel: +(351) 275329153
Fax: +(351)275329157
Appendices
b
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Appendix B
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Appendices
c
Concurrent resistance and aerobic training follow a detraining period in elementary school students.
Appendix C
EFFECTS OF CONCURRENT RESISTANCE AND ENDURANCE TRAINING/ DE-TRAINING
PROGRAMS ON PUBESCENT AND ADOLESCENTS PHYSICAL FITNESS PERFORMANCE.
Running Title: CONCURRENT RESISTANCE/ENDURANCE TRAINING AND DE-TRAINING
Albano P. Santos1,2
, Daniel A. Marinho1,2
, Aldo M. Costa 1,2
, Mikel Izquierdo3, Tiago M. Barbosa4,
Mário C. Marques1,2
1 Department of Sport Sciences, University of Beira Interior, Covilhã, Portugal
2 Research Centre for Sport, Health and Human Development, Portugal
3 Department of Health Sciences, Public University of Navarre, Navarre, Spain
4 Department of Sport Sciences and Physical Education, Polytechnic Institute of Bragança, Portugal
Correspondence to: Mário C. Marques, Phd
Department of Sport Sciences, University of Beira Interior –Portugal,
Rua Marquês D´Ávila e Bolama 6200-001 Covilhã, Portugal;
Tel: +(351) 275329153; Fax: +(351)275329157; E-mail: mariomarques@mariomarques.com
Abstract
Resistance training can offer unique benefits for children and adolescents when appropriately
prescribed and supervised. Comprehensive school-based programs are specifically designed to
enhance health-related components of physical fitness, which include muscular strength. However,
resistance school-based programs aiming an increase in physical fitness performance are less studied
and with inconclusive findings.
Objectives: The aim of this study was to synthesize information published in English language and
fulfilled the following criteria were included in this review: (i) experimental studies in children or
adolescents samples; (ii) at least one exercise intervention investigated resistance training.
Methods: A systematic database search for full-length manuscripts were performed on Sportdiscus,
Springerlink, Taylor & Francis, Sciencedirect, Wiley Interscience, and Pubmed for the 1980–2011
(September week 4) period. Four keyword categorical searches were conducted: (i) ‘resistance
training’, or ‘strength training’, or ‘weight training’; (ii) ‘child’, or ‘adolescent’, or ‘pediatric’; or
‘paediatric’ (iii) ‘concurrent’ and (iv) ‘de-training’, ‘recess’. The reference lists of each of these
studies and a number of review papers and position stands were manually searched to extract further
studies.
Conclusions: Concurrent training seems to be effective in pre- and post-pubescent boys and girls. It
can be assumed that concurrent strength/endurance training not only does not impair strength or
endurance development as seems to be an effective, well-rounded exercise program. Regarding to
de-training effects, studies that have been properly investigated the changes in resistance training-
induced strength gains during detraining in pre-adolescents are still scarce and insufficient. Even
after a period as long as 3 month, strength/endurance gains can be observed in untrained early to
post-pubescent youth.
Keywords: resistance, concurrent training, youth, school-based
Introduction
egular physical activity during
childhood and adolescence is
associated with improvements in
numerous physiological and psychological
variables and it has been extensively
documented in health related outcomes field
(Sallis and Patrick, 1994; U.S. Department of
Health and Human Services, 1996; Sallis et
al., 1997; U.S. Department of Health and
Human Services, 2010). Recommendation for
the amount of physical activity deemed
appropriate to yield beneficial health and
behavioural outcomes for school-age youth
have been also widely proposed (Sallis and
Patrick, 1994; U.S. Department of Health and
Human Services, 1996; Strong et al., 2005).
Muscle strength is one of the most important
health-related factors of physical fitness. By
definition, muscular strength refers to the
maximal force or tension a muscle or a group
of muscles can generate at a specified velocity
(Knuttgen and Kraemer, 1987; Ortega et al.,
2008). Resistance training refers to a
specialized method of conditioning, which
involves the progressive use of a wide range of
resistive loads and a variety of training
modalities designed to enhance health, fitness,
and sports performance (Faigenbaum et al.,
2009). Although the term resistance training,
strength training, and weight training are
sometimes used synonymously, the term
resistance training encompasses a broader
range of training modalities and a wider
variety of training goals (Faigenbaum et al.,
2009). The term weightlifting refers to a
competitive sport that involves the
performance of the snatch and clean and jerk
lifts (Faigenbaum et al., 2009). It’s largely
documented that in addition to aerobic
activities, research increasingly indicates that
resistance training can offer unique benefits
for children and adolescents when
appropriately prescribed and supervised (Yu et
al., 2005; American Academy of Pediatrics,
2008; Behringer et al., 2011).
Comprehensive school-based programs are
specifically designed to enhance health-related
components of physical fitness, which include
muscular strength (Wechsler et al., 2000;
National Association for Sport and Physical
Education, 2005). However, resistance school-
based programs aiming an increase in physical
fitness performance are less studied and with
inconclusive findings.
Therefore, the purpose of this research was to
systematically review the effects of resistance
training alone, concurrent resistance and
endurance training over physical performance
of 10 to 18 years old children and adolescents
to assess current knowledge and level of
evidence according to the Consolidated
R
Standards of Reporting Trials (CONSORT)
checklist guidelines (Mosher et al., 2001).
Methods
Inclusion and exclusion criteria
Research that were published in English
language and fulfilled the following criteria
were included in this review: (i) experimental
studies in children or adolescents samples
(aged 10-18 years old); (ii) at least one
exercise intervention investigated resistance
training (using machines, free weights, elastic
bands or tubes, medicine ball, body weight or
a combination of several), either in isolation or
as an adjunct to an alternative treatment.
Search protocol
A systematic database search for full-length
manuscripts were performed on Sportdiscus,
Springerlink, Taylor & Francis, Sciencedirect,
Wiley interscience, and Pubmed for the 1980–
2011 (September week 4) period.
First, four keyword categorical searches were
conducted: (i) ‘resistance training’, or
‘strength training’, or ‘weight training’; (ii)
‘child’, or ‘adolescent’, or pediatric, or
‘paediatric’; (iii) ‘concurrent’ and (v) ‘de-
training’, ‘recess’. The reference lists of each
of these studies and a number of review papers
and position stands were manually searched to
extract further studies.
Introduction
It’s strongly documented that resistance
training can offer unique benefits for children
and adolescents when appropriately prescribed
and supervised (Yu et al., 2005; Myer and
Wall, 2006; Faigenbaum et al., 2009;
Faigenbaum and Myer, 2010). Indeed,
improvements in muscular fitness and
speed/agility, rather than cardiorespiratory
fitness, seem to have a positive effect on
skeletal health (Ortega et al., 2008).
Strength training (also called resistance
training) refers to a specialized method of
physical fitness conditioning that comprises
the progressive use of a wide variety of
resistive loads — from medicine balls to high
intensity plyometric drills — that enhance or
maintain muscular fitness (Faigenbaum et al.,
1996; American Academy of Pediatrics, 2001;
British Association of Exercise and Sport
Sciences, 2004; Faigenbaum and Mediate,
2006; Myer and Wall, 2006; American
College of Sports Medicine, 2006; American
Academy of Pediatrics, 2008; Faigenbaum et
al., 2009; Faigenbaum and Myer, 2010).
Research into the effects of resistance exercise
on youth has increased over the past years
(Faigenbaum et al., 1996; British Association
of Exercise and Sport Sciences, 2004;
American College of Sports Medicine, 2006;
Faigenbaum and Mediate, 2006).
Consequently, youth strength training is,
nowadays, accepted by medical and fitness
organizations and this qualified acceptance is
becoming universal (Faigenbaum et al., 1996;
American Academy of Pediatrics, 2001;
British Association of Exercise and Sport
Sciences, 2004; American College of Sports
Medicine, 2006). Complementary, school
physical education is the primary societal
institution with the responsibility for
promoting physical activity in youth (Sallis et
al., 1997; Dobbins et al., 2009) and
comprehensive school-based programs, are
specifically designed to enhance among other
fitness components, muscular strength
(Faigenbaum and Mediate, 2006, Faigenbaum
et al., 2009).
Several factors seem to have an effect over
muscular strength and power development and
studies have been used different
methodologies and thus different results;
which led us to this systematic search.
Youth’s muscular strength trainability
The efficacy and success of a resistance
training programme on children has been
questioned in the past (Lillegard et al., 1997).
Children lack adequate circulating androgens
required for gains in muscular strength was
appointed as explainer of that ineffectiveness
(Legwold, 1982). Thus, different studies on
children have reported no significant strength
increases after the intervention period of
resistance training programme (Docherty et
al., 1987). A great range of reasons such as no
inclusion of control group, assessment testing
methods different from training drills,
inadequate loads (resistance, repetitions, or
sets), or a short study period can help to
explain the lack of significant strength gains
reported in those studies (Lillegard et al.,
1997). Conversely, numerous other studies
comparing strength trained children with age
and sex matched controls have shown strength
gains are possible (Ozmun et al., 1994) with
no detrimental effect on growth (Sadres et al.,
2001; Myer et al., 2005).
Pre-pubescent muscular strength trainability
Faigenbaum et al. (1993) found for both
genders and pre-pubescent population that
twice/wk strength training program can
increase significantly (p<.001) strength in
upper and lower limbs strength [10-RM leg
extension (64.5%), leg curl (77.6%), chest
press (64.1%), overhead press (87.0%), and
biceps curl (78.1%)] after strength training
program whereas gains in the control group
averaged 13.0% (range 12.2 to 14.1%) for the
same tested motions. The mean gains in
strength for the experimental group were
significantly greater than those for the control
group. In vertical jump and seated ball put,
subjects submitted to training programme
improved 13.8% and 4% respectively,
compared with 7.7% and 3.9% observed in
control group. There were no significant
interaction effects on vertical jump and seated
ball put; however, significant (p<.05) main
effects (both groups combined) for time were
found on both performance measures
(Faigenbaum et al., 1993).
Concordantly, Ozmun et al. (1994) for the pre-
pubescent boys and girls that significant
isotonic (22.6%), and isokinetic (27.8%)
strength gains and integrated EMG amplitude
(16.8%) increases were found after training
programme period without corresponding
changes in arm circumference or skinfolds.
For the authors (Ozmun et al., 1994) early
gains in muscular strength resulting from
resistance training by prepubescent children
may be attributed to increased muscle
activation.
The effectiveness of strength training program
in pre-pubescent boys and girls was confirmed
using 6RM leg extension strength and 6RM
chest press strength tests since exercise group
significant increased +53.5 and 41.1%,
respectively, compared with non-significant
increase of 6.4 and 9.5% in controls
(Faigenbaum et al., 1996). Significantly
greater gains in strength during the 2nd
phase
of training for 6RM leg extension and 6RM
chest press strength tests has been found,
comparing with controls (Faigenbaum et al.,
1996). After a training program of 1RM chest-
press exercise for either low or high
repetitions maximum, it has been found that
pre-pubescent boys are sensitive to gains in
1RM chest-press test (Faigenbaum et al.,
2005). That increase was about 52% for low
repetitions maximum and 66% for high
repetitions maximum, of their initial 1 RM
(Faigenbaum et al., 2005). More recently the
positive effect of strength training program
over strength variables was confirmed in
school context for pre-pubescent population
(Cowan and Foster, 2009).
Besides pre-pubescent subjects are
respondents to resistance training program, it
was demonstrated that after a plyometric
training programme pre-pubescent soccer
players boys can increase performance in
muscle power tests such as maximal cycling
power (p<.01), CMJ (p<.01), squat jump
(p<.05), multiple 5 bounds (p<.01), repeated
rebound jump for 15 seconds (p<.01) and
running velocity on 20m (p<.05). These
performances’ improvements in the treatment
group were reached without concomitant
performances’ improvements in controls
(Diallo et al., 2001).
As mentioned downward the effectiveness of
strength training in pre-pubescent subjects can
be reached with different training program
context such as sports-based (Diallo et al.,
2001; Garrido et al., 2010), fitness club-based
(Faigenbaum et al., 1996; Lillegard et al.,
1997; Faigenbaum et al., 2005; Yu et al.,
2005; Ingle et al., 2006) or school based
(Faigenbaum and Mediate, 2006;
Kotzamanidis, 2006; Cowan and Foster, 2009)
and resistance modes such as child sized
weight machines (Faigenbaum et al., 1993;
Faigenbaum et al., 1996, Faigenbaum et al.,
2005), free weights or common weight
machines (Lillegard et al., 1997; Garrido et al.,
2010), body weight/tubing exercises/dumbbell
exercises (Cowan and Foster, 2009; Sgro et
al., 2009; Garrido et al., 2010) and medicine
ball (Faigenbaum and Mediate, 2006; Cowan
and Foster, 2009; Sgro et al., 2009; Garrido et
al., 2010).
Post-pubescent muscular strength trainability
Strength training is also effective in pubescent
and in post-pubescent population as well. In a
pubescent male athletes sample, upper (bench
press) and lower [leg press (DeRenne et al.,
1996; Hetzler et al., 1997) and vertical jump
(Hetzler et al., 1997)] strength has been
increased after training period (DeRenne et
al., 1996; Hetzler et al., 1997). Tsolakis et al.
(2004) found that resistance training induced
strength changes independently of the changes
in the anabolic and androgenic activity.
A considerable number of studies has been
investigated the effects of resistance training
on adolescents. After a training period subjects
significantly increase predicted 1RM squat
(92%) and 1RM bench press (20%), right
(10.39cm) and left (8.53cm) single-leg hop
distance and vertical jump (3.3cm) and speed
in a 9.1-m sprint (0.07seconds) (Myer et al.,
2005). Basic resistance training alone induced
favourable neuromuscular and biomechanical
movement changes (Myer et al., 2005; Lephart
et al., 2005) providing greater sport-specific
training improvements (Szymanski et al.,
2007) in high school male (Myer et al., 2005;
Szymanski et al., 2007) and female (Lephart et
al., 2005) athletes.
In summary youth are indeed trainable and a
short bout of 10 to 15 minutes in each physical
education class it’s sufficient to achieve
significant gains in the shuttle run, long jump,
sit and reach flexibility, medicine ball
abdominal curl, medicine ball push up and
medicine ball toss (Faigenbaum and Mediate,
2006). The introduction of manual resistance
training on physical education class also
resulted in curl-up test (Dorgo et al., 2009).
Additionally, an important finding highlight
that performing resistance training at a
moderate volume is more effective and
efficient than performing at a higher volume
(González-Badillo et al., 2005): junior
experienced lifters can optimize performance
by exercising with only 85% or less of the
maximal volume that they can tolerate.
Onset physical fitness level effect
It’s well documented that resistance training is
effective on muscular strength development of
either untrained (Faigenbaum et al., 1993;
Ozmun et al., 1994; Faigenbaum et al., 1996;
Lillegard et al., 1997; Faigenbaum et al.,1999;
Faigenbaum et al.,2002; Tsolakis et al., 2004;
Yu et al., 2005; Faigenbaum et al., 2005;
Faigenbaum and Mediate, 2006; Shaibi et al.,
2006; Ingle et al., 2006; Kotzamanidis, 2006;
Faigenbaum et al., 2007; Cowan and Foster,
2009; Dorgo et al., 2009; Sgro et al., 2009;
Lubans et al., 2010) or trained ( DeRenne et al,
1996; Hetzler et al., 1997; Diallo et al., 2001;
González-Badillo et al., 2005, Lephart et al.,
2005; Myer and Wall, 2006; Christou et al.,
2006; Faigenbaum and Mediate, 2006;
Szymanski et al., 2007; Bogdanis et al., 2007;
Garrido et al., 2010) pre-pubertal (Faigenbaum
et al., 1993; Ozmun et al., 1994; Faigenbaum
et al., 1996; Lillegard et al., 1997; Faigenbaum
et al.,1999; Diallo et al., 2001; Faigenbaum et
al.,2002; Faigenbaum et al.,2005; Yu et al.,
2005; Kotzamanidis, 2006; Cowan and Foster
2009; Sgro et al., 2009) or pubertal/post-
pubertal non-adult population (DeRenne et al,
1996; Lillegard et al., 1997; Tsolakis et al.,
2004; Lephart et al., 2005; González-Badillo
et al., 2005; Ingle et al., 2006; Faigenbaum
and Mediate, 2006; Christou et al., 2006;
Myer and Wall, 2006; Shaibi et al., 2006;
Bogdanis et al., 2007; Szymanski et al., 2007;
Faigenbaum et al., 2007; Dorgo et al., 2009;
Lubans et al., 2010). Comparing with
untrained subjects, highly experience (at least
6 years) adolescents athletes in different sports
(basketball, soccer, and volleyball players)
girls, significantly increase predicted 1RM
squat and 1RM bench press performances, as
well as right and left single-leg hop distance,
vertical jump and speed 9.1-m running
performances; rise movement biomechanics:
increase knee flexion-extension range of
motion during the landing phase of a vertical
jump and decreased knee valgus and varus
torques (Myer and Wall, 2006). Another
research has been specifically investigated the
effect of sports experience on strength training
adaptation in adolescent males (Hetzler et al.,
1997): comparing with controls, experienced
training subjects and novice training subjects
significantly increased leg press, bench press
and vertical jump after a 12 weeks, thrice a
week, with free weights and machines.
Gender effects
Faigenbaum et al. (1996), Faigenbaum et al.
(1999), Faigenbaum et al. (2002), Faigenbaum
et al. (2005), Yu et al. (2005), Faigenbaum and
Mediate (2006), Sgro et al. (2009) and Lubans
et al. (2010) observed increases in various
training-induced strength gains in
prepubescent (Faigenbaum et al., 1996;
Faigenbaum et al.,1999; Faigenbaum et al.,
2002; Faigenbaum et al.,2005; Yu et al., 2005;
Sgro et al., 2009) and pubescent (Faigenbaum
and Mediate, 2006; Lubans et al., 2010) boys
and girls; however, details of the detraining
responses were not reported in those studies.
Cowen et al. (2009) found that boys and girls
revealed improvements in push up scores, curl
up scores, and overall percentile ranking after
a strength training program; however, the
statistical difference between both genders
was not reported. Lillegard et al. (1997)
observed no significant 3 or 2-way (gender,
Tanner’s stage, treatment) interactions for any
of 10 RM strength differences (barbell curl,
triceps extension, bench press, lat pull, leg
extension, leg curl) and for any of the 5 motor
performance parameters (flexed arm hang,
jump and reach, shuttle run, standing long
jump, 30 yard dash). However, when it was
considered the gender main effect, in 2 of the
six 10RM strength measures (lat pull, leg
extension), males had significantly gains then
females and significant pre- and post-test
genders difference occurred on shuttle run
(favoured the females) (Lillegard et al., 1997).
Program design
Resistance training programs as short as 10-15
minutes per session (Faigenbaum and Mediate,
2006), in addition to physical education
classes have been showed to be sufficient to
promote strength developments in paediatric
population. Different weekly training
frequency have been used such as once a week
(Faigenbaum et al.,1999; Faigenbaum et al.,
2002; Yu et al., 2005), twice a week
(Faigenbaum et al., 1993; Faigenbaum et al.,
1996; Faigenbaum et al.,2002; Faigenbaum et
al.,2005; Christou et al., 2006; Faigenbaum
and Mediate, 2006; Kotzamanidis, 2006;
Shaibi et al., 2006; Faigenbaum et al., 2007;
Garrido et al., 2010; Lubans et al., 2010;)
thrice a week (Ozmun et al., 1994; DeRenne et
al, 1996; Hetzler et al., 1997; Lillegard et al.,
1997; Diallo et al., 2001; Tsolakis et al., 2004;
Lephart et al., 2005; Myer et al., 2005; Yu et
al., 2005; Ingle et al., 2006; Szymanski et al.,
2007; Dorgo et al., 2009; Sgro et al., 2009) or
five days a week (González-Badillo et al.,
2005; Bogdanis et al., 2007; Cowan and
Foster, 2009) with success on strength
performances development. Strength training
programs using experienced non-adults
population lasted from 4 (Bogdanis et al.,
2007) to 24 weeks ( DeRenne et al., 1996).
When we focus our analysis on untrained non-
adults subjects studies, we found that the
mostly used period it has been 8 weeks (
Faigenbaum et al., 1993; Faigenbaum et al.,
1996; Faigenbaum et al., 1999; Faigenbaum et
al., 2002; Tsolakis et al., 2004; Faigenbaum et
al., 2005; Lubans et al., 2010). Training period
range has last from 6 ( Faigenbaum and
Mediate, 2006; Faigenbaum et al., 2007) to 64
(36+28) weeks (Yu et al., 2005). However,
significant gains in upper and lower limbs
strength can occur during a short period as the
first 4-weeks of a training program
(Faigenbaum et al., 1996).
Therefore, muscular strength can be improved
during childhood years, and favour a training
frequency a twice/week (Faigenbaum et al.,
2002), 1 set/exercise of a higher repetition
maximum (15-20 reps.) training range
(Faigenbaum et al., 2005) for untrained
children participating in an introductory
strength training program (Faigenbaum et al.,
2002).
Training Frequency
Faigenbaum et al. (2002) studied the effects of
week frequency (1 vs. 2 sessions/wk) of
strength training on upper and lower body
strength in non-prior strength training
experienced children. The 1-day group
training at a 62.3 and 68.8% intensity (of their
initial 1RM) on the chest press and leg press
exercises, respectively, whereas the 2-day
group trained at an intensity of 61.1 and 67.4%
(of their initial 1RM), respectively
(Faigenbaum et al., 2002). The authors found
that in 1RM chest press strength performance,
participants who trained 1 day/week increased
9.0% from their initial score whereas 2
days/week strength training group increased
11.5% [only this group made significantly
(p<.05) greater gains in this variable as
compared to the control group]. Compared
with baseline scores, 1 day/week training
group increased 14.2% in 1RM leg press
strength whereas 2 days/week strength training
group increased 24.9% (Faigenbaum et al.,
2002). Control group has increased 4.4 and
2.4% in first and second variable, respectively
(Faigenbaum et al., 2002). The authors
proposed that the control group’s strength
gains may be explained by growth, maturation,
and the learning effect. Despite no pre- post-
program significant differences between
groups were observed in handgrip strength,
long jump, vertical jump, and flexibility it can
be assumed that muscular strength can be
improved during childhood years, favouring a
training frequency of twice/week for children
participating in an introductory strength
training program. These results have to be
taken with caution as long as throughout the
study period 64% of subjects in the 1-day
group, 70% in the 2-day group, and 69% in the
control group regularly participated (at least 2-
day/week) in organized community sports
programs (mainly swimming and soccer) and
these last programmes were not controlled by
researchers.
Other authors ( DeRenne et al, 1996) have
been studied the effect of training week
frequency (1 vs. 2 sessions/wk) in 12 wks in-
season over strength gains retaining. Firstly,
all subjects (including control group) attended
to a preseason 12 wks, thrice a week of
progressive strength training. In in-season,
significant differences (p<.05) in absolute
strength scores between group which trained 2
day/wk and the control group prior to the
maintenance protocol for bench press were
observed. At the end of the 12-week in-season
period, subjects of both weekly training
frequencies (1 and 2 sessions/wk) differed
significantly (p<.05) from the control group in
absolute bench press strength scores.
Additionally, significant differences (in pre-
to post in-season program) between 1 and 2
sessions/wk training groups and the control
group were observed. No other differences
were observed between groups. During the
12- week maintenance protocol, group which
trained 1 day/wk had significant increases in
strength in the bench press (p<.05) while the
control group had significant decreases in the
bench press and pull-ups. Thus, for pubescent
male athletes, 1 day/wk maintenance program
is sufficient to retain strength performance
during the competitive season.
Training intensity and training volume
Trained adolescents of both genders can
benefit from a short session of strength
training. A 10 to 15 minutes of medicine ball
strength training program performed twice a
week on physical education classes have been
shown to be sufficient to significantly (p<.05)
promote gains in long jump, medicine ball
abdominal curl, medicine ball push up and
medicine ball toss tests (Faigenbaum and
Mediate, 2006).
González-Badillo et al (2005) found that
junior resistance-trained athletes can optimize
performance by exercising with only 85% or
less of the maximal volume that they can
tolerate. In fact, after a periodized routine
using the same exercises and relative
intensities but a different total number of sets
and repetitions at each relative load, the
authors observed that moderate-volume group
showed a significant increase for the snatch,
clean & jerk, and squat exercises (6.1, 3.7, and
4.2%, respectively, p<.01), whereas in the
low-volume group and high-volume group, the
increase took place only with the clean & jerk
exercise (3.7 and 3%, respectively, p<.05) and
the squat exercise (4.6%, p<.05, and 4.8%,
p<.01, respectively). The increase in the
snatch exercise for the moderate-volume
group was significantly higher than in the low-
volume group (p=.015). The study’s
(González-Badillo et al., 2005) results showed
higher strength gains in the moderate-volume
group than in the high-volume group or low-
volume group. There were no significant
differences between the low-volume group
and high-volume group training volume-
induced strength gains (González-Badillo et
al., 2005). These finding are consistent with
Faigenbaum et al. (1999) conclusions:
muscular strength and muscular endurance can
be enhanced in untrained pre-pubertal boys
and girls and favour the prescription of higher
repetition–moderate load resistance training
programs during the initial adaptation period”(
Faigenbaum et al., 1999). That study’s results
shows that in 1RM leg extension strength a
significant increase was observed in both
Low-Repetition-High-Load Group (+31.0%)
and High-Repetition-Moderate-Load Group
(+40.9%) compared with controls. In leg
extension muscular endurance both Low-
Repetition-High-Load Group and High-
Repetition-Moderate-Load Group significantly
increased compared with controls, although
gains resulting from High-Repetition-
Moderate-Load Group (13.1±6.2 repetitions)
were significantly greater than those resulting
from Low-Repetition-High-Load Group
(8.7±2.9 repetitions). In chest press 1-RM
strength and chest press muscular endurance
tests only the High-Repetition-Moderate-Load
Group made gains (16.3% and 5.2±3.6
repetitions, respectively) than gains in the CG
(Faigenbaum et al., 1999). More recently,
another study (Faigenbaum et al., 2005) in
untrained children which begin resistance
training, confirmed this thesis. Study’s results
(Faigenbaum et al., 2005) favour the
prescription of a higher RM training range (1
set of 15-20 RM): both Low-Repetition-
Maximum Group and High-Repetition-
Maximum Group made significant gains on 1
RM-strength (21% and 23%, respectively),
however, only the High-Repetition-Maximum
Group made significantly greater gains (42%)
on 15 RM local muscular endurance test
(Faigenbaum et al., 2005). Nevertheless future
longstanding studies are necessary to evaluate
the effects of different combination of sets and
repetitions on performance measures in non-
adult (Faigenbaum et al., 2005).
Training mode
Different modes such as medicine balls
(Faigenbaum and Mediate, 2006; Cowan and
Foster 2009; Sgro et al., 2009; Garrido et al.,
2010;), weighted bags (Sgro et al., 2009),
exercise machines (Faigenbaum et al., 1996;
Hetzler et al., 1997; Lilligard et al., 1997;
Faigenbaum et al.,1999; Faigenbaum et
al.,2002; González-Badillo et al., 2005;
Faigenbaum et al., 2005; Yu et al., 2005;
Garrido et al., 2010), dumbbells ( Hetzler et
al., 1997; Cowan and Foster 2009; Sgro et al.,
2009; Lubans et al., 2010) or elastic
bands/tubing (Cowan and Foster 2009; Sgro et
al., 2009; Lubans et al., 2010) have been used
successfully on strength training development
of both trained and untrained or pre- and
pubescent boys and girls. Notwithstanding we
didn’t find any study that has been specifically
compared de effect of different modes on
strength training development.
Conclusion
Summarising, when we considered the studies
which have investigated resistance training
alone, we found that pre-pubescent to early
post-pubescent boys and girls who participate
in a resistance training programme can
significantly raise upper and lower body
strength performance, enhance flexibility and
improve body composition as well. Different
training modes are effective on strength
training development of both trained and
untrained or pre- and pubescent boys and girls.
Moreover, performing resistance training a
minimum of 10-15 minutes twice a week, at a
moderate volume is more effective and
efficient than performing at a higher volume.
This is particularly important for school
context since usual available training
resources does not allow the usage of high
strength loads. When considering gender
effect, males seem to have greater strength
improvements then females.
Concurrent resistance and endurance
training
Adaptations as consequence of training
process are highly dependent on the specific
type of training implemented (Booth and
Baldwin, 1996; Zatsiorsky and Kraemer,
2006). Endurance training generally
encompasses exercise volume of several
minutes up to some hours at many exercise
intensities, increasing the ability to sustain
repetitive high-intensity, low-resistance
exercise with minimal fatigue accumulation
and minimal performance loss (Nader, 2006;
Bompa and Haff, 2009;). Resistance training
encompasses short-duration activities at high
exercise intensities, and increases the capacity
to perform high-intensity, high-resistance
exercise of a single or relatively few
repetitions, and throwing events in school or
sports field (Zatsiorsky, 2002; Nader, 2006).
Many researchers has rationalise that
concurrent training promote the benefits of
both resistance and endurance training (1993).
Nevertheless an inhibition in strength or
endurance adaptation as a consequence of
concurrent training has been reported (Volpe
et al., 1993). Sale et al. (1990) observed that
concurrent strength and endurance training
applied on different days produced gains
superior to those produced by concurrent
training on the same day. Although the
training programs were held otherwise
constant, alternate-day training was more
effective in producing maximal leg press
strength gains than same-day training. This
suggests that the interference effect may also
be true when the overall frequency and/or
volume of training are higher. Briefly, the
literature researches do not demonstrate the
universality of the interference effect in
strength development when strength training is
performed concurrently with endurance
training (Santos et al., 2011).
In the present analysis we did not considered
studies which has investigated resistance
training concurrently to subject’s sports
workouts. Thus we only considered the
researches that have been investigated the
concurrent resistance and aerobic endurance
training in untrained youth.
Concurrent resistance and endurance training
has been demonstrate to be effective even in
short periods of resistance training as 10 to 15
minutes for untrained adolescents of both
genders. Assuming that Physical Education are
mainly aerobic, subjects who participated in
medicine ball training program during the first
10 - 15 minutes of each Physical Education
class has significantly (p<.05) greater gains in
the shuttle run, long jump, sit and reach
flexibility, medicine ball abdominal curl,
medicine ball push up and medicine ball toss
as compared to the subjects who participated
in Physical Education lessons but not
medicine ball training (Faigenbaum and
Mediate, 2006).
Subjects who concurrently trained manual
resistance and cardiovascular endurance in
every Physical Education session has showed
significant improvements in one-mile run
(p<.002) and trunk lift (p<.0001) measures
from 0-9 and 9-18 wks compared with
subjects who trained manual resistance
training alone (Dorgo et al., 2009). Concurrent
training seems to be effective also in pre-
pubescent boys and girls. Cowan and Foster
(2009) observed significant improvements in
one-mile run, push up and curl up scores for
both genders after a concurrent strength and
endurance training period.
More recently, Santos et al. (2011) found that
concurrent resistance and endurance training is
effective on both upper and lower limbs
muscular power development of pubescent
girls. Only group who had included endurance
exercises on strength training program has
been increased endurance performance.
Conclusion
In concurrent resistance and endurance
training analysis we only considered the
research that has been investigated the
concurrent strength and endurance training in
untrained youth. Concurrent training seems to
be effective in pre-pubescent and post
pubescent boys and girls. It can be assumed
that concurrent strength and endurance
training not only does not impair strength or
endurance development as seems to be an
effective, well-rounded exercise program that
can be used as a means to improve initial or
general strength in youth.
De-training effects
Reversibility, one of the training’s
methodological principles, sustain that
whereas regular physical training results in
numerous physiological adaptations that
enhance physical and athletic performance,
stopping or markedly reducing training
induces a partial or complete reversal of these
adaptations, compromising performance
levels. Therefore, the reversibility principle
can be considered the principle of detraining
(Hawley and Burke, 1998).
De-training is defined as the partial or
complete loss of training-induced anatomical,
physiological and performance adaptations, as
a consequence of training reduction or
cessation (Mujika and Padilla 2000). Training
cessation implies a temporary discontinuation
or complete abandonment of a systematic
programme of physical conditioning (Mujika
and Padilla 2000). Reduced training is a non-
progressive standardised reduction in the
quantity of training (Mujika, 1998), which
may result in a maintenance or even in an
improvement of many of the positive
physiological and performance adaptations
acquired with training process (Houmard et
al., 1996; Mujika, 1998).
In this review de-training is defined as the
partial or complete loss of training-induced
anatomical, physiological and performance
adaptations, as a consequence of systematic
training cessation or reduction. Training
cessation refers to a temporary discontinuation
or complete abandonment of a systematic
programme of physical conditioning (Mujika,
1998).
Interruptions in training process because of
illness, injury, holidays, post-season break or
other factors are normal situations in
numerous kind of sport (Faigenbaum et al.,
1996; Faigenbaum and Mediate, 2006;
Faigenbaum et al., 2009) and in school context
as well. The extent of performance decrease
may depend upon the length of the period
recess in addition to training levels and
performance attained by the subjects (Marques
et al., 2008). Nevertheless, information about
the changes in resistance training-induced
strength gains during detraining in pre-
adolescents it’s still scarce (Tsolakis et al.,
2004) and insufficient studies (Blimkie, 1992;
Faigenbaum et al., 1996) have investigated the
effects of detraining with an inclusion of a
control group to control for growth-related
rises in muscular strength.
The maintenance of upper and lower body
muscular strength improvements such as
1RM, muscular strength endurance (DeRenne
et al, 1996) or muscle power (Diallo et al.,
2001) were observed in pubescent trained boys
after 8 weeks (Diallo et al., 2001) or 12 weeks
(DeRenne et al., 1996) period of reduced
strength training.
At the end of 8 weeks of detraining (absolute
training cessation), Faigenbaum et al. (1996)
observed that pre-pubescent untrained boys
and girls, significant loss 6RM leg extension (-
28.1 %) and chest press (-19.3%) strength.
Lower limbs muscular strength loss was made
mainly during the first 4 weeks of detraining
(6RM extension: -21.3%) while upper limb
muscular strength loss was about half during
the first 4 weeks (chest press: -8.9%) and
albeit EG values remained significantly higher
than CG values. Nevertheless, at end of the 8-
week detraining period, the chest press but not
leg extension strength of the subjects who
have strength trained remained significantly
greater than controls. Concordantly, in pre-
and early pubertal untrained males the same
trend can be found (Tsolakis et al., 2004).
After 8 weeks of detraining, Tsolakis et al.
(2004) fount that the trained subjects' strength
(concentric strength of the elbow flexion in
the right arm, assessed by an upper extremity
dynamometer; and 10RM elbow flexion with
adjustable dumbbells) decreased significantly
by 9.5%, converging toward the control
values. The week degree of the initial strength
gain and the detraining extent could partly
explain the reversible response of strength
(Blimkie, 1992). Nevertheless, despite that
observed strength loss, the treatment group
maintained about by 64% of the strength
gained during training program, probably
due to the high intensity of the training
program (Kraemer et al., 1989), which is an
important factor related to the magnitude of
the improvement of the muscular strength
(Blimkie and Bar-Or, 1996).
In this line, the benefits of upper and lower
body complex training (in pre- and early
pubertal boys) are lost at similar rates to other
training modalities at the end of 12 weeks of
training recess (Ingle et al., 2006).
Conversely, in pre- and early pubertal boys
and girls swimmers, it was observed that at the
end of 6 weeks of detraining period strength
parameters remained stable and swimming
performance still improved (Garrido et al.,
2010), however all the swimmers maintained
the normal swimming program, without any
strength training. Thus, this study cannot be
compared with previous since subjects of
treatment and controls continued on their usual
swimming training and thereby recess effects
can be biased by swimming training.
More recently and inconsistently with
previous studies, it was shown that in early
pubertal and adolescents untrained girls, 12
weeks of de-training period was not sufficient
to reduce the overall training effects. No
significant changes were observed after a
recess period in any of the treatment groups
(strength training group and concurrent
strength and endurance training group) for
medicine ball toss and sprint running.
Resistance training group kept jump
(horizontal and vertical distance) and
concurrent strength and endurance training
group maintained the endurance performance
(Santos et al., 2011).
Conclusion
Studies that have been properly investigated
the changes in resistance training-induced
strength gains during de-training in pre-
adolescents are still scarce and insufficient.
Different results have been found on de-
training effect over subject’s strength gains.
However, it can be assumed that even after a
period as long as 3 month, strength and
endurance gains can be observed in untrained
early to post-pubescent boys and girls.
Summary and conclusions
Despite of consensus exists from The British
Association of Sport & Exercise Science
(Stratton et al., 2004), The American
Academy of Pediatrics (2008), The American
College of Sports Medicine (Faigenbaum,
2000; Lavalee, 2005), and the National
Strength and Conditioning Association (1996),
with other recommendations summarized by
Faigenbaum et al. (2009), Fulton et al. (2004)
and Twisk (2001), that resistance training
since appropriately designed and supervised
by expert personnel is beneficial to children
and adolescents’ athletic performance, health
and fitness, there is a scarcity of robustly
designed studies investigating the main factors
which determine concurrent strength and
endurance training gains and detraining effect
(school-based) in untrained children and
adolescents. Muscular strength has been
recognized as an important component of
fitness in the recent evidence-based physical
activity guidelines for school-age youth
(Strong et al., 2005). Despite there is clear
data in adults (Lavalee, 2005) to support these
positions, evidence-based data in children and
adolescents are limited. However, available
data suggest that well-designed and supervised
resistance training programmes may have
beneficial health outcomes associated with
cardiorespiratory fitness (Faigenbaum, 2000;
Stratton et al., 2004) and it would be
improvident to ignore those findings while the
depth of evidence in non-adult population is
being established.
Ours findings are important to increase de
effectiveness of endurance and strength
training design of untrained children and
adolescents in school context.
It’s well documented that endurance training
program results in VO2max raise but more
studies are needed to clarify what is the best
school-based program’s methodology on
endurance training in paediatric population.
A minimum of 10-15 minutes twice week of
resistance training is sufficient to improve
strength and moderate volumes are more
effective and efficient than higher volumes.
This is particularly important for school
context since usual available training
resources does not allow the usage of high
strength loads. When considering gender
effect, males seem to have greater strength
improvements then females.
Concurrent strength and endurance training
not only does not impair strength or endurance
development as seems to be an effective, well-
rounded exercise program that can be used as
a means to improve initial or general strength
in youth.
Studies that have been properly investigated
the changes in resistance training-induced
strength gains during de-training in pre-
adolescents are still scarce and insufficient.
However, from published studies it can be
assumed that even after a period as long as 3
month, strength and endurance gains can be
observed in untrained early to post-pubescent
boys and girls.
This study is consistence with previous studies
which highlight the role of school as the
primary institution in physical fitness
promoter.
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