[Exercise and other lifestyle factors for prevention of osteoporosis during growth and young adulthood].

Increased mechanical loading of the skeleton results in bone gain, whereas unloading the skeleton leads to bone loss. Regular exercise, especially resistance and high-impact activities, contributes to development of high peak bone mass and the greatest effects on bone mass appear to occur in early adolescence. Therefore, it seems reasonable to turn our attention to intervening in the younger population to establish lifelong exercise habit that maximize peak bone mass. Adequate calcium intake together with exercise is crucial to develop optimal peak bone mass and to preserve bone mass throughout life. This lifelong exercise may prevent osteoporosis and reduce fracture risk by attenuating age-related bone loss and lowering the incidence of falls. Moreover such lifestyle as sitting on Tatami mat could also stimulate bone accumulation in early adolescent girls. Sports participation may offset the negative effect of smoking on bone mass.