FEMUR TROCHANTER BONE DENSITY DOSE-RESPONSE TO PROGRESSIVE STRENGTH TRAINING IN 140 POSTMENOPAUSAL WOMEN

Abstract

Recent evidence supports an osteogenic effect of strength training exercise in postmenopausal women. The dose-response relationship between the amount of weight lifted in one year of strength training and change in femur trochanter bone mineral density (BMD) was examined in a group of 140 exercising post-menopausal women: 70 taking and 70 not taking hormone replacement therapy. At three weekly sessions, the women performed eight different exercise designed to strengthen most large muscles. Duel energy x-ray absorptiometry (DXA) was used to measure total body and regional BMD at baseline and one year. A significant increase in trochanter BMD (1.68 ± 3.39%) was found. In multiple linear regression, a significant, positive relationship was found between total weight lifted and change in trochanter BMD (p < .015). A change of .001 g/cm2 in trochanter BMD was predicted for each standard deviation (SD) of weight lifted. The regression model was adjusted for age, baseline trochanter BMD, change in body weight, study entry time (cohort), and training facility. A comparable model was produced for each of the individual exercises. Weighted squats exhibited the strongest effect on trochanter BMD (.002 g/cm2 per SD of weight lifted; p < .001) followed by the military press (.001 g/cm2 per SD of weight lifted; p < .01). In the back extension each SD of weight lifted was expected to produce a change in BMD of only. .0004 g/cm2. It was concluded that the total weight lifted in some strength training exercises over a 1-year period was positively and significantly associated with the amount of BMD change in the femur trochanter. Supported by NIH AR 39559 and Mission Pharmacal