Effect of physical activity during teenage years, based on type of sport and duration of exercise, on bone mineral density of young, premenopausal Japanese women

In this cross-sectional study, 91 healthy premenopausal women aged 20-39 ye ars were investigated to determine the effect of physical activities during their teenage years on their current bone mineral densities (BMD). We meas ured whole-body BMD (WBMD), lumbar BMD (LBMD), and radial BMD (RBMD) with d ual energy X-ray absorptiometry (DXA). Using a questionnaire, we asked the women about their physical activities during junior and senior high school and at present. We also asked about their current nutritional status and pa st and current milk intaker After adjusting for age, body mass index (BMI), current total calorie and calcium (Ca) intake, and milk intake when they w ere teenagers and at present, we determined that subjects who exercised dur ing extracurricular activities at each of the three periods (during junior and senior high school and at present) had significantly higher WBMD and LB MD (P < 0.01, respectively) than did those who did not exercise at those ti mes. Subjects who played high-impact sports at each period had significantl y higher WBMD and LBMD than did subjects who played low-impact sports (P < 0.05, respectively). Subjects who had exercised regularly from their teenag e years to the present had significantly higher BMD at all sites than BMD i n other subjects after adjusting for the potential confounders described ab ove (P < 0.05, respectively). Our data suggest that continuous exercise beg inning in junior high school, especially high-impact sports, may be associa ted with greater current bone mass. It is important to incorporate adequate exercise beginning in the teenage years to lower one's future risk for ost eoporosis.