title: Effect of water temperature on cooling efficiency during hyperthermia in humans.
abstract: We evaluated the cooling rate of hyperthermic subjects, as measured by rectal temperature (T(re)), during immersion in a range of water temperatures. On 4 separate days, seven subjects (4 men, 3 women) exercised at 65% maximal oxygen consumption at an ambient temperature of 39 degrees C until T(re) increased to 40 degrees C (45.4 +/- 4.1 min). After exercise, the subjects were immersed in a circulated water bath controlled at 2, 8, 14, or 20 degrees C until T(re) returned to 37.5 degrees C. No difference in cooling rate was observed between the immersions at 8, 14, and 20 degrees C despite the differences in the skin surface-to-water temperature gradient, possibly because of the presence of shivering at 8 and 14 degrees C. Compared with the other conditions, however, the rate of cooling (0.35 +/- 0.14 degrees C/min) was significantly greater during the 2 degrees C water immersion, in which shivering was seldom observed. This rate was almost twice as much as the other conditions (P < 0.05). Our results suggest that 2 degrees C water is the most effective immersion treatment for exercise-induced hyperthermia.
authors.affiliation: Faculty of Health Sciences, University of Ottawa, Ottawa Ontario, Canada K1N 6N5.
authors.forename: C I
authors.initials: CI
authors.lastname: Proulx
authors.forename: M B
authors.initials: MB
authors.lastname: Ducharme
authors.forename: G P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D001831:Body Temperature; D003080:Cold Temperature; D015444:Exercise; D005260:Female; D005334:Fever / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D007101:Immersion; D008297:Male; D012007:Rectum / Q000503:physiopathology; D013696:Temperature; D014867:Water
chemical_list: D014867:Water