Abstract To examine the responses of the endocrine system to moderate-resistance training in younger (YO) verses middle-aged (MI) men, two groups of men (21 and 49 years-old) participated in 8-week moderate-resistance training program three times per week. Blood was obtained before, immediately after, and 30 min after exercise at before and after training period for analysis of total tes- tosterone, cortisol, GH, lactate and ACTH. Squat and bench press strength, and circumference of thigh and arm increased for both groups. After training, resting testos- terone and GH increased in YO; testosterone concentra- tions were also increased for YO and MI from pre-training values. However, GH values decreased in MI after training period. Cortisol and ACTH values were lower compared to similar times in pre-training. These data indicate that middle-aged men do respond with an enhanced hormonal profile in the early phase of a resistance training program, but the response is different from that of younger men.
