Abstract:
Physical activity (PA) has been described as one of the best strategies to optimize skeletal development during
growth. In this study, at baseline 81 boys and 53 girls aged 7-9 years were included in a curriculum-based exercise
intervention program comprising 40 minutes of PA per school day. Age and gender-matched 57 boys and 50 girls,
assigned to the general Swedish school curriculum of 60 minutes PA per week, served as controls. Both boys and
girls in the intervention group had significantly higher accrual of bone mineral content and larger gain in bone size in
the lumbar vertebrae. No exercise-induced bone mineral accrual or structural changes were observed at the femoral
neck. The PA measured by accelerometers was high so that all children reached the international recommended level
of 60 minutes of moderate to vigorous PA per day. Children who participated in the exercise intervention groups were
reported to experience more of the highest intensities of physical activities. This study has identified that a schoolbased
exercise intervention program in pre-pubertal children enhances the skeletal benefits at the lumbar spine but
not bone mineral accrual or structural changes at the femoral neck.
