Evolutionary
analysis of physical strength capacity in Ecuadorian physical education
Abstract
The aim of this literature review was
to analyze the evolution of physical strength within the context of school
physical education, considering variables such as age, sex, and pedagogical
intervention methods. To this end, more than 40 studies published between 2000
and 2024 in specialized databases such as PubMed, Scopus, and SciELO were
reviewed. The results show that muscle strength develops naturally, linked to
maturational processes, with a significant increase during puberty, especially
in boys, due to hormonal factors (increased testosterone) and changes in body
composition. In girls, progress is more gradual and less pronounced, although
it also improves with appropriate training programs. The study demonstrates
that the inclusion of specific strength training methods, adapted to each
developmental stage, has a positive effect on both improving strength and
preventing injuries, as well as on developing basic motor skills. The
literature highlights that strength training at an early age, if properly
planned and supervised, does not pose health risks, debunking myths about
possible negative effects on growth. It concludes that the didactic treatment
of strength in school physical education should consider developmental and
gender differences, as well as the individualization of workloads and methods,
to promote the student's comprehensive development.
Keywords: Strength,
Physical Education, Training, Motor Skills, Physical Capacities
Introduction
Strength is one of the
fundamental physical capacities that underpin motor development and physical
performance in school-aged children. Its appropriate stimulation from an early
age not only contributes to improved performance in sports and recreational activities,
but also plays a crucial role in injury prevention, the adoption of active
lifestyles, and the promotion of overall health ( Stricker et al., 2020; Garthe
et al., 2020). In the context of Physical Education, strength development has
been the subject of debate due to the existence of myths related to its impact
on the growth and maturation of children and adolescents (Moran et al., 2018;
Lesinski et al., 2020).
Several studies have shown that
strength development is closely linked to biological factors such as age, sex,
hormonal changes, and neuromuscular adaptations, which determine the
differences in the development of this capacity throughout childhood and
adolescence (Moreno-Torres et al., 2025; Miñanes -Rufo et al., 2023). However,
the effectiveness of intervention programs in schools also depends on
pedagogical factors, such as the correct dosage of training loads, the choice
of appropriate methods, and consideration of each student's individual
characteristics (de Souza et al., 2022; Fernández-Chacón & Bayas-Machado,
2021).
Furthermore, the literature has
highlighted that well-structured strength training programs not only improve
overall physical fitness but also boost self-esteem, adherence to physical
activity, and academic performance in schoolchildren ( Faigenbaum et al., 2016;
Masanovic et al., 2020). Incorporating strength exercises into the physical
education curriculum has demonstrated benefits in both body composition and
metabolic health parameters, underscoring its importance in preventing chronic
non-communicable diseases from an early age ( Stricker et al., 2020;
García-Hermoso et al., 2018).
Furthermore, it has been shown
that the response to strength stimuli varies according to the level of
biological maturation of children and adolescents, which implies the need to
design adapted programs that respect individual developmental stages to avoid
the risk of overload or stagnation of progress ( Behm et al., 2017; Moran et
al., 2018). Similarly, the integration of playful and motivational
methodologies has proven effective in increasing active participation and
enjoyment among schoolchildren during training sessions (García-Roca et al.,
2020; Marcillo Iza et al., 2022).
Gender differences influence
strength development, as males typically reach higher levels of absolute
strength after puberty, while girls show more moderate increases due to
hormonal and structural factors. However, both sexes improve significantly with
well-adapted strength training programs ( Lesinski et al., 2020; Miñanes -Rufo
et al., 2023).
This literature review analyzes
the evolution of physical strength capacity in the educational field, compiling
scientific evidence on its development at different school stages and offering
didactic guidelines for its appropriate implementation in Physical Education.
It highlights the importance of planning strength training based on principles
of individualization, progression, and variety, incorporating alternative
materials and motor games that promote a holistic approach, encompassing
physical, psychological, and social dimensions (Fernández-Chacón &
Bayas-Machado, 2021; García-Roca et al., 2020; Moquera Nazareno & Suntaxi ,
2024).
Methodology
A systematic literature review was conducted following the PRISMA
guidelines ( Preferred Reporting Items for Systematic Reviews and Meta-
Analyses ) to ensure rigor, transparency, and reproducibility in the selection
and analysis of studies (Page et al., 2021). This approach is widely recognized
in sports science and physical education research for its ability to
objectively synthesize the available scientific evidence ( Moher et al., 2009).
The search was conducted between January and May 2025 in the specialized
databases Scopus , PubMed, Web of Science and EBSCO were selected for their
relevance in the areas of health sciences, sports, and education. The search
strategy included controlled and free-text terms such as: “strength,” “
resistance training,” “ strength training,” “muscular fitness,” “ child ,” “
adolescent ,” and “ physical .” education ”, combined using boolean operators
(AND/OR) to optimize the retrieval of relevant articles ( Lesinski et al.,
2020; Garthe et al., 2020).
The search limits included publications between 2018 and May 2025, in
English and Spanish, in order to incorporate recent studies that reflect
current trends in strength training in school populations (Moran et al., 2018;
de Souza et al., 2022).
Inclusion criteria:
Studies with school population between 6 and 18 years old.
Direct (dynamometry, 1RM, vertical jump) or indirect (physical test
batteries) assessments of strength capacity.
Methodological design of the type meta-analysis, systematic review or
experimental/intervention study.
Studies developed in school contexts or whose applicability is directly
to school Physical Education.
Exclusion criteria:
Research with adult populations (>18 years) or focused on
high-performance athletes, because their physiology and training contexts
differ substantially from the school population ( Faigenbaum et al., 2016).
Articles without access to full text, which prevents a comprehensive
evaluation of the methodology and results.
Observational studies that did not include intervention or that did not
specifically evaluate the strength variable ( Masanovic et al., 2020).
The study selection process included the reading of titles, abstracts,
and full texts by two independent reviewers, with discrepancies resolved by
consensus or consultation with a third reviewer, following the recommendations
of Moher et al. (2009). The methodological quality of the included studies was assessed using
the PEDro tool for clinical trials or AMSTAR-2 for systematic reviews and
meta-analyses ( Shea et al., 2017), ensuring the internal validity of the
integrated evidence.
Population
and sample
The target population consisted of scientific studies related to the
development of strength capacity in schoolchildren. The final sample comprised
30 key studies selected after an initial screening process of over 1000
records. The
sample included:
Additionally, 3 studies conducted in Ecuador were considered, which
provided specific data on the national context.
Methods,
techniques and procedures
The methodological process was developed in the following phases:
Systematic bibliographic search in the indicated databases, applying the
descriptors and filters of date, language and school population.
Screening of titles and abstracts to discard irrelevant studies (n=1000
initial records).
Full text review to assess the methodological and thematic relevance of
the preselected articles (n=85).
Application of PRISMA criteria for the final selection (n=30 studies),
ensuring methodological quality and thematic relevance.
Data extraction from each selected article: study design, sample size,
age and gender of participants, duration and intensity of interventions,
variables evaluated (maximum strength, muscle endurance, power, VO2max ), main
findings and pedagogical recommendations.
Narrative and comparative synthesis of results, differentiating by age
groups (6–11 and 12–18 years), sex and type of intervention.
Results
and discussion
·
The evolution of strength follows a pattern of progressive increase
associated with neuromuscular maturation in childhood (6–11 years) and hormonal
factors (especially in males) in adolescence (12–18 years).
·
Calisthenics interventions and motor games in children showed
significant improvements in strength-endurance without requiring specialized equipment.
·
Structured strength programs (HIIT, progressive loads) of 6–12 weeks
demonstrated improvements in maximum strength and power in adolescents, with
notable increases in VO₂max and speed.
·
A sustained global decline in muscle strength and endurance was observed
since the 1990s, associated with sedentary lifestyles and less time spent on
physical activity at school.
·
The differences between the sexes were minimal in prepuberty , widening
after puberty in favor of males in absolute strength, but not in relative
strength.
·
No negative effects on growth, epiphyseal plates, or bone health were
reported when the interventions were supervised and well-dosed.
·
Cognitive (attention, working memory) and emotional (self-esteem)
improvements were evident after 8-week strength programs.
·
Ecuadorian studies confirmed these global trends, with specific findings
such as a positive correlation between frequency of physical activity and
strength, and a decrease in strength-endurance in sedentary schoolchildren.
Table 1. Summary of
Effects of Force Interventions by Age Group
|
Age Group |
Type of Intervention |
Main Results |
Additional comments |
|
6 – 11 years (childhood) |
Calisthenics ( push -ups,
planks , curl -ups), motor games, recreational activities |
Improved
strength-endurance, coordination, neuromuscular activation |
No changes in muscle
mass; cognitive benefits observed (attention, concentration) |
|
12-18 years
(pre-adolescence and adolescence) |
Calisthenics + HIIT +
strength training with progressive overload (40-60% 1RM) |
Increase in absolute
strength (greater in males), muscle power, VO₂max , speed |
Hormonal changes
(testosterone/estrogens) make a difference in absolute strength gains |
Table 2. Effects of
Strength Training on Physical, Metabolic, Cognitive and Psychosocial Variables
|
Variable evaluated |
Observed effects |
Level of evidence* |
Comments |
|
Muscle strength |
↑ Maximum strength,
strength-endurance, power |
High |
Best results with
programs ≥6 weeks, 2-3 sessions/week |
|
Body composition |
↓ Body fat, ↑
lean mass |
Moderate |
Associated with
progressive overload and calisthenics programs |
|
Bone mineral density |
↑ Bone density
without epiphyseal plate involvement |
High |
Supervised training does
not pose a risk to growth |
|
Metabolic health |
↑ Insulin
sensitivity, improved lipid profile |
Moderate |
More consistent effects
in adolescents; lack of longitudinal studies |
|
Cognition |
↑ Attention,
working memory |
Moderate |
8-week strength +
endurance programs show improvements |
|
Emotional state |
↓ Anxiety, ↑
self-esteem |
Low to moderate |
Need for more specific
controlled studies |
|
Academic performance |
Trend towards improvement
in executive functions |
Low |
Insufficient longitudinal
school studies |
Table 3. Main
Differences by Sex and Biological Maturation
|
Variable / Age |
Prepuberty (6–11 years) |
Puberty (12–18 years) |
Key comments |
|
Relative strength
(relative to body weight) |
Minimal differences
between the sexes |
Marked increase in
post-pubertal males |
Influence of testosterone
in men |
|
Absolute strength |
Similar in boys and girls |
Higher in males |
Related to muscle mass
and bone mass |
|
Response to training |
Primarily neuromuscular |
Obvious hypertrophy in
men |
The girls are improving,
but to a lesser extent. |
|
Motivation and adherence |
No clear differences
reported |
Few studies
differentiated by sex |
It is recommended to
investigate self-efficacy and motor perception. |
Level of evidence (according to a synthesis
of reviewed studies):
·
High: Consistent results in ≥3 high-quality studies.
·
Moderate: Consistent results, but with methodological limitations or
heterogeneity.
·
Low: Limited or inconsistent evidence.
The findings of this review reaffirm the importance of integrating strength training into school physical education from an early age, as an essential strategy for the comprehensive development of children and adolescents. Numerous studies agree that well-structured and supervised strength training programs not only increase physical capacity (Moran et al., 2018; Lesinski et al., 2020), but also provide benefits in metabolic terms (reduced risk of obesity and insulin resistance), bone health (increased bone mineral density), cognitive function (improvements in executive functions), and psycho-emotional well-being. (increased self-esteem and intrinsic motivation) ( Faigenbaum et al., 2016; Stricker et al., 2020).
Scientific
evidence confirms that strength training in school-aged children is safe and
effective with proper supervision, even in pre-pubertal and pubescent children.
Its planning should be tailored to the level of biological maturation, also
considering socio-environmental factors that affect their development. However,
gaps remain in the research, such as the lack of longitudinal studies and
standardized protocols. A playful, progressive and individualized approach is
recommended , with the involvement of families and continuous training of
teachers to ensure the adherence and effectiveness of these programs (
Behringer et al., 2010; Myer et al., 2013; Lloyd & Oliver, 2012; Marcillo
Iza et al., 2022; Frómeta et al., 2019; Garthe et al., 2020; Moran et al.,
2018; Rodríguez-Rodríguez et al., 2022; de Souza et al., 2022; Miñanes -Rufo et
al., 2023; González-Cutre et al., 2019; Stricker et al., 2020; Moquera Nazareno
& Suntaxi , 2024).
Conclusions
The findings of this review highlight the
importance of systematically and strategically including strength-building
activities in school physical education programs. These activities not only
contribute to improving specific physical abilities but also have a positive
impact on students' bone, metabolic, and psychological health, reducing the
risk of chronic diseases in adulthood. This demonstrates that strength training
extends beyond mere athletic pursuits, establishing itself as a cornerstone of
holistic health and well-being during the school years.
Despite scientific evidence, myths persist
about the risks of strength training in school children. Therefore, it is
essential to update the training of physical education teachers, integrating
the latest advances in this area to implement safe, effective, and motivating
strategies that promote the holistic development of students.
The analysis shows that the effectiveness of
strength training in school-aged children depends largely on personalizing
programs according to individual characteristics, such as biological age, level
of maturation, gender, and initial physical condition. Adapting the load,
volume, and intensity is crucial to maximizing benefits and minimizing risks,
underscoring the need for an individualized pedagogical approach in Physical
Education.
In addition to program design, extrinsic
factors such as family support, school culture, and access to suitable
facilities play a crucial role in motivating and ensuring the continuity of
strength training in children and adolescents. Interventions should involve the
educational and family community to promote active and healthy lifestyles,
facilitating the incorporation of strength training as a long-term habit.
Acknowledgments
To all the professionals in the Sciences of Physical Activity and Sports
who help to nurture the knowledge and research of our profession every day.
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