Lifetime calcium intake and physical activity habits: independent and combined effects on the radial bone of healthy premenopausal Caucasian women.

Lifetime calcium intake and lifetime physical activity (PA) habits of 181 healthy premenopausal Caucasian women (aged 20-50) were studied. Nondominant arm was measured by single-photon absorptiometry at the distal (Dis) or 5-mm site and the midshaft (Mid) or two-thirds site of the radius. Values of bone mineral content (BMC), bone width (BW), and bone mineral density (BMD) were obtained. An intermediate or high lifetime Ca (greater than 500 mg/d) was significantly associated with a greater DisBMC (p = 0.0031), DisBMD (p = 0.0031), MidBMC (p = 0.0015), and MidBMD (p = 0.0015) when adjusted for PA. Similarly, with Ca adjusted for, a high lifetime PA (greater than or equal to 45 min of moderate to strenuous activity four times a week) was significantly associated with greater DisBMC (p = 0.0032), DisBMD (p = 0.0022), MidBMC (p = 0.0012), MidBW (p = 0.0173), and MidBMD (p = 0.0546). These findings suggest important roles for both adequate Ca intake and PA habits in enhancing peak adult skeletal mass and a trade-off between these two variables, when each was intermediate or higher.