Effect of Exercise on Serum Sex Hormones in Men

Abstract

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 middleaged 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, dihydrotestosterone (DHT), 3α-androstanediol glucuronide (3α-Diol-G), estradiol, free estradiol, and sex hormonebinding 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 (VȮ 2max ) 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 VȮ 2max at 3 and 12 months in exercisers. No statistically significant differences were observed for testosterone, free testosterone, 3α-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. NIH Public Access Author ManuscriptMed Sci Sports Exerc. Author manuscript; available in PMC 2011 February 16. An age-associated decline of serum testosterone after the fourth to fifth decades of life in men has been observed not only cross-sectionally (61), but also longitudinally in large cohort studies (13,65). A combination of changes in testicular function, altered neuroendocrine regulation of Leydig cells, and increased binding capacity of sex hormonebinding globulin (SHBG) results in approximately 40% lower testosterone levels among men in their 70s compared with men in their 20s (12,25,28). Given the many health changes that also occur in men as they age, the possibility of a relationship between the decline in androgens and these health changes has, not surprisingly, been an area of active investigation. Low levels of testosterone in men have been associated with decreased sexual function, loss of muscle mass and strength, osteoporosis, declining cognitive function, and poorer quality of life (28). Further, the age-related decline in testosterone is associated with increased body fat, insulin resistance, and other metabolic risk factors (36). Despite the common belief to the contrary...

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Impact of physical activity and exercise on male reproductive potential: a new assessment questionnaire

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