THE EFFECT OF ENVIRONMENTAL-TEMPERATURE ON TESTOSTERONE AND CORTISOL RESPONSES TO HIGH-INTENSITY, INTERMITTENT EXERCISE IN HUMANS

The purpose of this study was to examine the testosterone, cortisol, a nd the molar ratio of testosterone to cortisol (T:C) blood concentrati on responses to intermittent, high intensity exercise in the heat. Eig ht active men [mean age 25 (SD 3) years, mass 71.1 (SD 5.5) kg, height 175.9 (SD 4.4) cm] performed two series of five 15-s Wingate anaerobi c power tests in both hot (H, 35 degrees C) and thermoneutral (TN, 22 degrees C) environments. Each period of exercise was separated by 30-s of active recovery. Each series was separated by 60 min of passive re covery. Blood samples were obtained before (PRE), immediately post (IF ), and 5(5R), 10(10R), 15(15R), 30(30R), 45(45R), and 60(60R) min foll owing exercise. Peak power was significantly higher, during the first series of exercise, in the H compared to TN. No significant difference s were seen in any of the variables between the first and second serie s of exercise in either environmental condition. Furthermore, no signi ficant differences between these conditions were observed in heart rat e, blood lactic acid concentration, or rectal temperature. A significa nt decrease in cortisol concentration was observed between PRE and IF, during both conditions. However, no significant interactions between TN or H were seen. No change from PRE was observed in testosterone or T:C during either TN or H. It would appear that testosterone and corti sol respond similarly to repeated periods of short duration high inten sity exercise, in either thermoneutral or moderately hot environments.