Six-year longitudinal analysis shows physical activity impacts on lean mass development in adolescence

THE STUDY of physical activity effects on muscle and bone in youth is largely limited to cross-sectional comparisons among athletic and nonathletic groups and short-term inter- vention studies often less than one year. Critical to the field is the impact of physical activity throughout the develop- mental years on the musculoskeletal system and especially muscle and bone mass. With the development of a healthy muscle and bone mass, children will be better protected from the chronic diseases of osteoporosis and sarcopenia in