Analysis of Regional Differences in Bone Mineral Density Acquisition Factors in Young Women

Purpose: Obtaining high peak bone mass (PBM) and maintaining bone mass is important for the prevention of osteoporosis. This study aimed to examine the regional differences in bone mineral density and factors associated with its acquisition from exercise. Design: The study population included 75 women of 18 - 22 years of age in East Japan and 104 women of 18 - 27 years of age in West Japan. The speed of sound (SOS) of the calcaneus was measured, and the young adult mean (%YAM) was calculated from the SOS. The subjects’ medical history, family history of osteoporosis, and exercise habits were examined using a self-administered questionnaire. Results: There were a significantly greater number of subjects with low %YAM in West Japan. The exercise history and exercise time were significantly higher in West Japan, and the exercise intensity score tended to be higher in East Japan during junior high and high school. A multiple regression analysis by region revealed that the following factors had a significant positive association with the SOS: exercise intensity at elementary school and outdoor sports at junior high school in East Japan; and exercise time at elementary school, muscle mass, and outdoor sports at junior high school in West Japan. On the other hand, exercise time in junior high school in West Japan showed a negative association with the SOS. Conclusions: Regional differences in bone mineral density existed, suggesting a trend toward lower bone mineral density in West Japan. Exercise history and time tended to be higher in West Japan, and exercise intensity scores tended to be higher in East Japan, suggesting that exercise intensity may be more important than exercise time for obtaining bone mineral density.