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Effects of heavy-resistance training on hormonal responses

Older men demonstrated a significant increase in total testosterone in response to exercise stress; this occurs along with significant decreases in resting cortisol in the early phase of a resistance training program. A study examined the adaptations of the endocrine system to heavy-resistance training in younger vs. older men. Two groups of men (30 and 62 years old) participated in a 10-week strength-power training program. Researchers analyzed total testosterone, free testosterone, cortisol, growth hormone, lactate, and ACTH. A heavy-resistance exercise test was used for evaluation (4 sets of 10-repetitions of maximum squats with 90 seconds of rest between sets). Results showed that squat strength and thigh muscle cross-sectional area increased in both groups. However, the younger group demonstrated, 1) higher total and free testosterone and insulin-like-growth-factor (IGF) than the older men, 2) training induced increases in free testosterone at rest and with exercise, and 3) increases in resting IGF-binding protein-3. With training, the older group demonstrated a significant increase in total testosterone in response to exercise stress along with significant decreases in resting cortisol. This indicates that older men do respond with an enhanced hormonal profile in the early phase of a resistance training program: the response, however, differs from that of younger men.

J.APPL.PHYSIOL. 1999 Vol 87 Iss 3 pp 982-992