AEROBIC POWER AND BODY-SIZE AFFECTS THE EXERCISE-INDUCED STRESS HORMONE RESPONSES TO VARYING WATER TEMPERATURES

Eleven active male subjects were used to examine the effects of anthro pometrics and aerobic power (Vo(2)max) on the plasma cortisol (CO) and urine excretion of catecholamines (NE and E) and dopamine (D) during exercise in differing water temperatures. Each performed 30 min of cyc le ergometer exercise at 60% Vo(2)max while immersed to the neck in 20 , 25, 30, and 35 degrees C water (Tw). The change in core temperature (triangle Tre) during exercise was related to Tw (p < 0.007). Plasma C O (exercise - rest) increased during the 20 degrees C trials and decre ased during the 30 and 35 degrees C trials (p = 0.011). Catecholamines were generally higher during the 20 and 35 degrees C trials than the 25 and 30 degrees C trials, with significance for only D and NE during the 35 degrees C vs. 25 degrees C trials (p < 0.05). Multiple regress ion analyses (MRA) with CO during the 20 degrees C trials revealed tha t Vo(2)max and triangle Tre were significant partial correlates (p < 0 .05), white in 35 degrees C water body mass index and triangle Tre wer e significant partial correlates (p < 0.05). MRAs with NE and E during the 20 degrees C trials indicated that body fat was the only consiste nt significant partial correlate. The MRA for NE and E during the 35 d egrees C trials were not significant; however, the MRA for D wets sign ificant. These results indicate that in addition to the core temperatu re, anthropometrics, and aerobic power affect the exercise induced str ess hormone responses during exposures to cold and warm water.