Purpose: The main purpose of this study was to analyze the impact of a 1-yr resistance-training program on body composition and muscle strength in postmenopausal women, and to describe the impact of hormone replacement therapy (HRT) on body composition changes, with and without exercise. Secondarily, we wanted to study dose-response relationships between measures of program compliance and changes in primary outcomes.
Methods: Subjects were postmenopausal women (40-66 yr) randomly assigned to an exercise (EX) group (N = 117) and a nonexercise group (N = 116). The EX group participated in a 1 yr trainer-supervised resistance-training program, 60-75 min.d-1, 3 d.wk-1. Lean soft tissue (LST) and fat tissue (FT) changes were measured by dual-energy x-ray absorptiometry and strength by one-repetition maximum testing.
Results: Significant (P < 0.001) gains in LST were observed for women who exercised, regardless of HRT status, whereas women who did not exercise lost LST (P < 0.05) if they were not taking HRT, and gained LST (P = 0.08) if they were on HRT. The only significant FT losses were observed for women who exercised while on HRT (P < 0.05). Strength increases were observed at all sites (P < 0.001). Total weight lifted by subjects in their training sessions was a significant predictor of changes in LST (P < 0.001) and strength (P < 0.01).
Conclusions: Resistance and weight-bearing exercise significantly changed total and regional body composition in postmenopausal women by increasing LST in all women and decreasing FT in women on HRT. Hormone therapy showed no independent effects on body composition, but it protected nonexercising women from losses in LST. The lean and muscle strength changes observed were partially dependent on the volume of training, as expressed by attendance and total weight lifted in 1 yr of training.