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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

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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).

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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.

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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:

•

4 international meta-analyses on strength training in schoolchildren.

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•

2 systematic reviews (one global and one Ibero-American).
•

24 original studies of intervention or strength assessment in a school context.

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).

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•

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

VO

₂

max 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%	Increase in absolute strength (greater in males), muscle power, VO ₂ max ,	Hormonal changes (testosterone/estrogens) make a difference in absolute strength gains

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Age Group	Type of Intervention	Main Results	Additional comments
1RM)	speed

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

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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

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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

Recent literature confirms that strength is an essential capacity that can be effectively developed

from school age through supervised and adapted training (such as calisthenics, HIIT or resistance

training),

with

a

minimum

frequency

of

2-3

times

per

week

for

at

least

6

weeks,

contributing

comprehensively to the physical, cognitive and metabolic health of students.

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

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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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Effects

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A

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review and meta-analysis

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Faculty of Physical Culture

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