title: Core temperature differences between males and females during intermittent exercise: physical considerations.
abstract: We examined differences in dynamic heat balance between males and females during intermittent exercise. Six males (M) and six females (F) performed three 30-min bouts of exercise (Ex1, Ex2, Ex3) at a constant rate of metabolic heat production (M - W) of approximately 500 W separated by three 15-min periods of inactive recovery. Rate of total heat loss (M - W) was measured by direct calorimetry, while M - W was determined by indirect calorimetry. Esophageal (T (es)) was measured continuously. Exercise at a constant M - W of approximately 500 W, was paralleled by a similar HL between sexes at the end of Ex1 (M: 462 +/- 30 W, F: 442 +/- 9 W, p = 0.117), Ex2 (M: 468 +/- 28 W, F: 508 +/- 18 W, p = 0.343), and Ex3 (M: 469 +/- 17 W, F: 465 +/- 13 W, p = 0.657). Consequently, changes in body heat content were comparable after Ex1 (M: 218 +/- 21 kJ, F: 287 +/- 35 kJ, p = 0.134), Ex2 (M: 109 +/- 18 kJ, F: 158 +/- 29 kJ, p = 0.179), and Ex3 (M: 92 +/- 19 kJ, F: 156 +/- 35 kJ, p = 0.136). However, females had greater overall increases in T (es) at the end of Ex3 (M: 0.55 +/- 0.25 degrees C, F: 0.97 +/- 0.26 degrees C, p <OR= 0.05). Differences in core temperature between sexes appear to be solely related to differences in physical characteristics, and not due to concurrent differences in whole-body thermoregulatory responses.
authors.affiliation: Laboratory of Human Bioenergetics and Environmental Physiology, School of Human Kinetics, University of Ottawa, 125 University Pvt, Ottawa, ON, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gagnon
authors.forename: Lucy E
authors.initials: LE
authors.lastname: Dorman
authors.forename: Ollie
authors.initials: O
authors.lastname: Jay
authors.forename: Stephen
authors.initials: S
authors.lastname: Hardcastle
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D001831:Body Temperature / Q000502:physiology; D002153:Calorimetry, Indirect; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D005082:Physical Exertion; D012727:Sex Characteristics; D022722:Thermogenesis / Q000502:physiology*; D014870:Water Loss, Insensible