title: Plasma testosterone and cortisol responses to training-intensity exercise in mild and hot environments.
abstract: Seven endurance-trained and heat-nonacclimated men (Mean+/-SEM: 20+/-1 yr; VO2max = 67+/-2 ml x kg(-1) x min(-1)) ran in two environments (M: 23 degrees C, H: 38 degrees C; 7 days apart) at two absolute training-intensity velocities (S1: 240 m x min(-1); followed by S2: 270 m x min(-1); 10 min each) during the winter months. Blood samples were taken via cannula before (pre) S1 and after S1 and S2. Plasma testosterone (TEST) concentrations increased (p<0.05) above pre levels after S1 in M (19+/-3 versus 24+/-3 nmol x L(-1)) and H (18+/-2 versus 23+/-3 nmol x L(-1)), and after S2 in H (18+/-2 versus 24+/-1 nmol x L(-1)). Plasma cortisol (CORT) and the molar ratio of TEST/CORT were unchanged from pre levels after S1 and S2 during M and H. No differences were found in plasma TEST, CORT, or the molar ratio of TEST/CORT between M and H. These results indicated that circulating levels of TEST and CORT were not changed in endurance-trained, heat-nonacclimated athletes in response to short-duration running performed at the same absolute intensity in the heat, compared to mild environmental conditions. The lack of significant differences in the molar ratio of TEST/CORT, between the 23 degrees C and 38 degrees C trials, suggested that this short-duration exercise challenge performed in the heat was no more of an anabolic or catabolic stimulus for these athletes.
authors.affiliation: The University of Connecticut, Human Performance Laboratory, Department of Sport, Leisure, and Exercise Science, Storrs 06269-1110, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Kenefick
authors.forename: C M
authors.initials: CM
authors.lastname: Maresh
authors.forename: L E
authors.initials: LE
authors.lastname: Armstrong
authors.forename: J W
authors.initials: JW
authors.lastname: Castellani
authors.forename: M
authors.initials: M
authors.lastname: Whittlesey
authors.forename: J R
authors.initials: JR
authors.lastname: Hoffman
authors.forename: M F
authors.initials: MF
authors.lastname: Bergeron
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D001143:Arousal / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D006359:Heat Exhaustion / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D010807:Physical Endurance / Q000502:physiology; D012420:Running / Q000502:physiology*; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D006854:Hydrocortisone