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Developmental Changes in Isometric Strength: Longitudinal Study in Adolescent Soccer Players.
Joao P Duarte1,2, João Valente-Dos-Santos2,3, Manuel J Coelho-E-Silva1,2
1Faculty of Sports Sciences and Physical Education, University of Coimbra, Coimbra, Portugal.
International Journal of Sports Medicine
|June 21, 2018
Summary
This study tracked knee extensor and flexor strength in young athletes over five years. Chronological age and fat-free mass were key predictors of isometric strength development.
Area of Science:
- Pediatric sports science
- Human physiology
- Biomechanical analysis
Background:
- Adolescent athletic development requires understanding muscle strength progression.
- Longitudinal data on knee muscle strength is crucial for identifying potential impairments.
Purpose of the Study:
- To longitudinally examine changes in isometric knee extensor (ImKE) and knee flexor (ImKF) strength.
- To identify predictors of isometric strength development in young athletes.
- To establish predictive models for ImKE and ImKF strength.
Main Methods:
- Longitudinal study of 67 male athletes (11.0-13.9 years at baseline) over five years.
- Measurements included stature, body mass, skinfolds, and isometric strength at 30° and 60°.
- Fat-free mass (FFM) derived from skinfolds; multilevel regression analyses used for modeling.
Main Results:
- Annual increases in chronological age (CA) significantly predicted isometric strength.
- Each 1 kg increase in FFM positively correlated with increased isometric strength.
- Developed polynomial regression models predicting ImKE and ImKF strength based on CA and FFM.
Conclusions:
- Chronological age and fat-free mass are significant longitudinal predictors of knee muscle strength in adolescents.
- Skeletal maturity showed a negligible effect on strength development.
- Regular assessment of knee extensor and flexor strength is recommended during adolescence.
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