A POTENTIAL METHOD FOR EVALUATING TESTOSTERONE SECRETION

Abstract

Explanations for the mechanism of acute exercise induced increase in serum testosterone (T) were conflicting in previous studies. In order to explore if the increase in serum testosterone is due to an increase in testosterone secretion, total testosterone (TT) and free testosterone (FT) in serum were repeatedly assayed in the incremental workload exercise test (IWLE-t) and human chorionic gonadotrophin (hCG) stimulating test (hCG-st). Healthy adult volunteers (15) without endocrinopathic history were randomly divided into hCG group (8 of 15) and control group (7 of 15), in which 1000u hCG or isometric saline was injected intramuscularly between 6:00 and 6:30 on the 2nd day of the 5-day experiment. Two IWIE-ts were conducted on the 1st and 5th day of the experiment. Blood samples were drawn before and immediately after each IWIE-t and hCG-st but these FT changes were uncorrelated. However, there were a close correlation between the powers at anaerobic threshold (PAT) (r = 0.84) and that between the TT values (r = 0.92) in two IWIE-ts in the control group, which implied that the enhanced serum TT might return to the baseline under the relatively invariant body condition. After hCG administration, the PAT was unchanged even though the TT value at the 80th hour increased. The TT change induced by IWIE-t was closely correlated with that stimulated by hCG-st, which indicated that IWIE-t could be used as a method for evaluating testosterone secretion.