Exercise and androgen levels
Physical exercise has been found to be associated with changes in androgen levels. In cross-sectional analyses, aerobic exercisers have lower basal total and free testosterone compared to the sedentary. Anaerobic exercisers also have lower testosterone compared to the sedentary but a slight increase in basal testosterone with resistance training over time. There is some correlation between testosterone and physical activity in the middle aged and elderly. Acutely, testosterone briefly increases when comparing aerobic, anaerobic and mixed forms of exercise. A study assessed men who were resistance trained, endurance trained, or sedentary in which they either rested, ran or did a resistance session. Androgens increased in response to exercise, particularly resistance, while cortisol only increased with resistance. DHEA increased with resistance exercise and remained elevated during recovery in resistance-trained subjects. After initial post-exercise increase, there was decline in free and total testosterone during resistance recovery, particularly in resistance-trained subjects. Endurance-trained subjects showed less change in hormone levels in response to exercise than resistance-trained subjects. Another study found relative short term effects of aerobic, anaerobic and combined anaerobic-aerobic exercise protocols on hormone levels did not change. The study noted increases in testosterone and cortisol immediately after exercise, which in 2 hours returned to baseline levels. Aerobic In trained long term aerobic exercisers, basal levels are unchanged, or decreased. Acutely, endurance based aerobic efforts cause testosterone to rise. A year long, moderate-intensity aerobic exercise program increased DHT and SHBG in sedentary men age 40–75, but had no effect on other androgens. Both DHT and SHBG increased 14% in exercisers at 3 months, and at 12 months they remained 9% above baseline. SHBG is protective against DHT as it binds free androgen. In acute assessment of hormone levels in soccer players before, during and after a game, DHT and testosterone increased during the match, but returned to baseline after 45 minutes rest. Aerobic exercise in Japanese rats done on a rodent treadmill doubled local concentrations of DHT in calf muscles as assessed by protein assay. After intense aerobic effort, high endurance athletes were also found to have lower free testosterone the next day. In prolonged endurance exercise, such as a marathon, levels ultimately decrease. Similarly, DHT drops, while adrenal androgen and cortisol will increase with the stress response. Anaerobic It is unknown if anaerobic training changes individual hormone profiles, or if conditioned athletes in studies self-selected because of physiologic predisposition to athletic conditioning. There is variation of response to anaerobic stress depending on exercise intensity, age, gender, length of time studied, and time at which serum indices were drawn. Most studies report that testosterone increases or is unchanged acutely, though some even report it to decrease. Anaerobic exercisers have testosterone levels below sedentary controls in cross sectional analysis. Over months to years, levels are stable to slightly increased. The ratio of testosterone to cortisol can both increase and decrease during resistance training, depending on intensity of exercise. A study comparing young and old subjects showed acute increases in GH and testosterone for both, although