Effects of exercise training and hormone replacement therapy on lean and fat mass in postmenopausal women

Background. Menopause is associated with decreases in lean mass and increases in fat mass. Serum hormone levels and hormone replacement therapy (HRT) may modify the effects of exercise training on body composition in postmenopausal women. Methods. We assessed the changes in total body and regional lean soft tissue and fat mass (using dual-energy x-ray absorptiometry) in 94 sedentary postmenopausal women, aged 40-65 years, after 12 months of resistance and weight-bearing aerobic exercise training. Women currently on oral HRT (n = 39) and not on HRT (n = 55) were randomized within groups to exercise and no exercise, resulting in four groups: exercise + HRT (n = 20), HRT (n = 22), exercise (n = 24), and control (n = 28). Fasting blood samples were measured for resting serum total levels of estrone, estradiol, cortisol, androstenedione, growth hormone, and insulin-like growth factor 1 at baseline and 12 months. Results. We found significant effects of exercise on increases in total body, arm, and leg lean soft tissue mass, and decreases in leg fat mass and percentage of body fat. There were no interaction effects of exercise and HRT on the changes in muscle strength and body composition. No significant changes in total hormone levels were found after 12 months. Conclusions. Exercise training resulted in significant beneficial changes in lean soft tissue and fat mass in early postmenopausal women. These changes in body composition were neither influenced by prolonged HRT use nor accompanied by changes in total levels of the hormones determined in this study.