An increase in school-based physical education increases muscle strength in children

Med Sci Sports Exerc. 2013 May;45(5):997-1003. doi: 10.1249/MSS.0b013e31827c0889.


Purpose: Children and adolescents are encouraged to maintain a habitually active lifestyle because of the known health benefits associated with regular physical activity, but there are some reports that a high level of activity may be associated with increased fracture risk. This prospective controlled exercise intervention study in prepubertal children evaluated if a school-based exercise intervention could enhance growth-related gains in muscle strength and muscular function without affecting fracture risk.

Methods: Fractures were registered in 417 girls and 500 boys age 7-9 yr in the intervention and in 836 age-matched girls and 872 boys. The intervention included 40 min·d of school physical education for 2 yr, whereas the controls achieved 60 min·wk. In a subsample consisting of 49 girls and 80 boys in the intervention and 50 girls and 53 boys in the control group, body composition was measured by dual-energy x-ray absorptiometry, muscle strength by isokinetic peak torque (PT) of the knee extensors, and flexors at 60 and 180°·s by a computerized dynamometer and neuromuscular performance by vertical jump height.

Results: The rate ratio (95% confidence interval) for children in the intervention group to sustain a fracture was 1.07 (0.66-1.68). The annual gain in knee extensor PT at 180°·s was significantly higher for both girls (P < 0.001) and boys (P < 0.01) in the intervention compared with the control group. Boys in the intervention group also had a greater annual gain in knee flexion PT at 180°·s (P < 0.001), and girls had a greater gain in vertical jump height (P < 0.05).

Conclusion: An increase in school-based physical education from 60 to 200 min·wk enhanced muscle strength in prepubertal children without affecting fracture risk.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Composition / physiology
  • Child
  • Female
  • Fractures, Bone / epidemiology*
  • Health Behavior
  • Humans
  • Life Style
  • Male
  • Muscle Strength*
  • Muscle, Skeletal / physiology
  • Physical Education and Training*
  • Physical Fitness / physiology*
  • Prospective Studies