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Hydration and Thermoregulation during a Half-Ironman Performed in Tropical Climate

Abstract : The aim of this study was to compare the core temperature (TC) and markers of hydration status in athletes performing a half Ironman triathlon race in hot and humid conditions (27.2 ± 0.5°C, relative humidity was 80 ± 2%). Before and immediately after the 2012 Guadeloupe half Ironman triathlon, body mass and urine osmolality (mean ± SD) were measured in 19 well-trained male triathletes. TC was measured before and after the race, and at each transition during the event, using an ingestible pill telemetry system. Ambient temperature and heart rate (HR) were measured throughout the race. Mean ± SD performance time was 331 ± 36 minutes and HR was 147 ± 16 beats·min-1. Wet bulb globe temperature (WBGT) averaged 25.4 ± 1.0°C and ocean temperature was 29.5°C. The average TC at the beginning of the race (TC1) was 37.1 ± 0.7°C; it was 37.8 ± 0.9°C after swimming (TC2), 37.8 ± 1.0°C after cycling (TC3), and (TC4) 38.4 ± 0.7°C after running. Body mass significantly declined during the race by 3.7 ± 1.9 kg (5.0 ± 2.4%; p < 0.05), whereas urine osmolality significantly increased from 491.6 ± 300.6 to 557.9 ± 207.9 mosm·kg-1 (p < 0.05). Changes in body mass were not related to finishing TC or urine osmolality. Ad libitum fluid intake appears applicable to athletes acclimatized to tropical climate, when performing a half Ironman triathlon in in a warm and humid environment.
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Contributor : Philippe Simon <>
Submitted on : Friday, May 15, 2015 - 10:32:07 PM
Last modification on : Thursday, May 23, 2019 - 5:34:03 PM


  • HAL Id : hal-01152333, version 1



Michelle Baillot, Olivier Hue. Hydration and Thermoregulation during a Half-Ironman Performed in Tropical Climate. Journal of Sports Science and Medicine, University of Uludag, 2015, 14 (2), pp.263-268. ⟨hal-01152333⟩



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