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International Journal of Pediatrics
Volume 2010, Article ID 307063, 9 pages
Clinical Study

A School-Based Exercise Intervention Program Increases Muscle Strength in Prepubertal Boys

1Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences, Lund University, 22100 Lund, Sweden
2Department of Orthopedics, Malmö University Hospital, 205 02 Malmö, Sweden
3Department of Medicine, Western Hospital, The University of Melbourne (RMH/WH), Footscray, Melbourne, Australia

Received 15 January 2010; Revised 15 April 2010; Accepted 26 April 2010

Academic Editor: Neil Armstrong

Copyright © 2010 Susanna Stenevi-Lundgren et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This prospective controlled intervention study over 12 months evaluated the effect of exercise on muscular function, physical ability, and body composition in pre-pubertal boys. Sixty-eight boys aged 6–8 years, involved in a general school-based exercise program of 40 min per school day (200 min/week), were compared with 46 age-matched boys who participated in the general Swedish physical education curriculum of mean 60 min/week. Baseline and annual changes of body composition were measured by dual energy X-ray absorptiometry (DXA), stature, and body mass by standard equipments, isokinetic peak torque (PT) of the knee extensors, and flexors at 60 and 180 deg/sec by computerized dynamometer (Biodex) and vertical jump height (VJH) by a computerized electronic mat. The annual gain in stature and body mass was similar between the groups whereas the increase in total body and regional lean mass ( ) and fat mass ( ) was greater in the exercise group. The one-year gain in body mass-adjusted knee extensor and flexor PT at 180 deg/sec was significantly greater in the intervention group compared with the control group ( , adjusted for age at baseline and , adjusted for age and muscle strength at baseline, resp.). There was no group difference in VJH. In conclusion, the increase in school-based physical education from 60 to 200 minutes per week enhances the development of lean body mass and muscle strength in pre-pubertal boys.