Prevention of Involutional Bone Loss by Exercise

Abstract

To ascertain whether exercise could prevent involutional bone loss, 18 postmenopausal women, half of whom exercised for 1 h 3 times/wk, were studied. Total and regional bone mass were measured before and after 1 yr of exercise by total-body neutron activation analysis (total body Ca) and photon absorptiometry (bone mineral content) of the distal radius. Total body K was measured by whole body counting. Bone mineral content and total body K did not change significantly in either group. Total body Ca increased in the exercise group from 781 .+-. 95 g to 801 .+-. 118 g (SD). In contrast, total body Ca decreased in each subject in the sedentary group. The daily Ca balance derived from the difference in total body Ca measurements was significantly different in the 2 groups of women (P < 0.001). These data support the hypothesis that exercise can modify involutional bone loss.