PHYSICAL EXERCISE INCREASES BONE-MINERAL DENSITY IN POSTMENOPAUSAL WOMEN

To examine whether physical exercise is beneficial in preventing postm enopausal osteoporosis, we measured bone mineral density (BMD) in thre e distinct groups of healthy postmenopausal Japanese women aged 49-61 yrs: 11 volleyball players (V) and 5 joggers (j), and 9 controls (C) w ho had not been participating in regular physical activity. BMD was me asured at the lumbar spine (L2-L4) and proximal femur using dual energ y X-ray absorptiometry, and at the radius using single X-ray photon ab sorptiometry. Serum levels of estradiol (E2), parathyroid hormone (PTH ) and calcitonin were also measured by radioimmunoassay. Osteocalcin w as determined by enzyme immunoassay. BMD in the lumbar spine was great er in the V and J groups than in the C group (P<0.01). The J group had a significantly lower PTH level than the C group. In contrast to weig ht-bearing bones, we found no significant differences in BMD at the ra dius among the three groups. BMD at the distal radius was negatively c orrelated with years after menopause in both the V group and the J gro up significantly. These results indicate that regular physical exercis e has a positive effect on the maintenance of bone mineral in postmeno pausal women and that the protective action is localized in skeletal s ites used predominantly for the sport without opposing the negative re gulation caused by estrogen deficiency in systemic bones.