Are calcium intakes and physical activity patterns during adolescence related to radial bone mass of white college-age females?

The determinants of bone mass, i.e., size and density, in young adult women after cessation of growth in length of the bones are not well understood. Usual dietary calcium (Ca) intakes and physical activity (PA) patterns during the post-pubertal half-decade have been considered as two important factors contributing to bone mass. In the present hypothesis-generating cross-sectional study, radial bone mineral content and density were measured by single-photon absorptiometry at two sites containing different proportions of trabecular and cortical bone tissue in 705 healthy, Caucasian college women (18-22 years). Ca intake during high school and college, as estimated by milk and cheese intake only, was categorized into low, moderate and high groups; and physical activity, estimated during the same time frame, was also categorized into low, moderate and high groups. Bone measurements were related to both long-term dietary Ca intake from milk and cheese and long-term PA in sports, dance or other exercises, as assessed by recall. By univariate analyses, both distal and mid-radial bone mineral content (BMC) and areal bone mineral density (BMD) were found to be positively related to gynecological age (GA) (p less than 0.01). Also, independent effects of long-term Ca intake (p less than 0.05) on distal BMC and BMD, and of long-term PA (p less than 0.05) on distal and mid-BMC and BMD were observed.(ABSTRACT TRUNCATED AT 250 WORDS)