title: Aerobically trained individuals have greater increases in rectal temperature than untrained ones during exercise in the heat at similar relative intensities.
abstract: To determine if the increases in rectal temperature (T(REC)) during exercise in the heat at a given percent of VO2peak depend on a subject's aerobic fitness level. On three occasions, 10 endurance-trained (Tr) and 10 untrained (UTr) subjects (VO2peak: 60 +/- 6 vs. 44 +/- 3 mL kg(-1) min(-1), P < 0.05) cycled in a hot-dry environment (36 +/- 1 degrees C; 25 +/- 2% humidity, airflow 2.5 m s(-1)) at three workloads (40, 60, and 80% VO2peak). At the same percent of VO2peak, on average, Tr had 28 +/- 5% higher heat production but also higher skin blood flow (29 +/- 3%) and sweat rate (20 +/- 7%; P = 0.07) and lower skin temperature (0.5 degrees C; P < 0.05). Pre-exercise T(REC) was lower in the Tr subjects (37.4 +/- 0.2 vs. 37.6 +/- 0.2; P < 0.05) but similar to the UTr at the end of 40 and 60% VO2peak trials. Thus, exercise T(REC) increased more in the Tr group than in the UTr group (0.6 +/- 0.1 vs. 0.3 +/- 0.1 degrees C at 40% VO2peak and 1.0 +/- 0.1 vs. 0.6 +/- 0.3 degrees C at 60% VO2peak; P < 0.05). At 80% VO2peak not only the increase in T(REC) (1.7 +/- 0.1 vs. 1.3 +/- 0.3 degrees C) but also the final T(REC) was larger in Tr than in UTr subjects (39.15 +/- 0.1 vs. 38.85 +/- 0.1 degrees C; P < 0.05). During exercise in the heat at the same relative intensity, aerobically trained individuals have a larger rise in T(REC) than do the untrained ones which renders them more hyperthermic after high-intensity exercise.
authors.affiliation: Exercise Physiology Laboratory at Toledo, University of Castilla-La Mancha, Avda. Carlos III, s/n, 45071, Toledo, Spain. Ricardo.Mora@uclm.es
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mora-Rodriguez
authors.forename: Juan
authors.initials: J
authors.lastname: Del Coso
authors.forename: Nassim
authors.initials: N
authors.lastname: Hamouti
authors.forename: Emma
authors.initials: E
authors.lastname: Estevez
authors.forename: Juan F
authors.initials: JF
authors.lastname: Ortega
mesh_terms: D000293:Adolescent; D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D012007:Rectum / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply; D012881:Skin Temperature / Q000502:physiology; D013546:Sweating / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology; D055815:Young Adult