Effect of exercise on serum sex hormones in men: a 12-month randomized clinical trial

Purpose: The effect of exercise on androgens in middle-aged to older men is poorly understood, and it could have implications for several aspects of health. This analysis was conducted to examine the effects of long-term aerobic exercise on serum sex hormones in middle-aged to older men. Methods: One hundred two sedentary men, ages 40-75 yr, were randomly assigned to a 12-month exercise intervention or a control group (no change in activity). The combined facility- and home-based exercise program consisted of moderate/vigorous-intensity aerobic activity for 60 min.d(-1), 6 d.wk(-1). Serum concentrations of testosterone, free testosterone, dilrydrotestosterone (DHT), 3 alpha-androstanediol glucuronide (3 alpha-Diol-G), estradiol, free estradiol, and sex hormone binding globulin (SHBG) were measured at baseline, 3, and 12 months. Results: Exercisers trained a mean of 370 min.wk(-1) (102% of goal), with only two dropouts. Cardiopulmonary fitness (VO2max) increased 10.8% in exercisers and decreased by 1.8% in controls (P<0.001). DHT increased 14.5% in exercisers versus 1.7% in controls at 3 months (P=0.04); at 12 months, it remained 8.6% above baseline in exercisers versus a 3.1% decrease in controls (P=0.03). SHBG increased 14.3% in exercisers versus 5.7% in controls at 3 months (P=0.04); at 12 months, it remained 8.9% above baseline in exercisers versus 4.0% in controls (P=0.13). There were significant trends toward increasing DHT and SHBG, with greater increases in VO2max at 3 and 12 months in exercisers. No statistically significant differences were observed for testosterone, free testosterone, 3a-Diol-G, estradiol, or free estradiol in exercisers versus controls. Conclusions: A yearlong, moderate-intensity aerobic exercise program increased DHT and SHBG, but it had no effect on other androgens in middle-aged to older men.