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Core temperature and hydration status during an Ironman triathlon
P B Laursen1, R Suriano, M J Quod
1School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia. p.laursen@ecu.edu.au
British Journal of Sports Medicine
|March 25, 2006
Summary
Well-trained triathletes can tolerate up to 3% body mass loss during an Ironman triathlon without adverse effects on core body temperature or performance. This field study contrasts with lab findings, suggesting greater resilience in real-world endurance events.
Area of Science:
- Sports Science
- Exercise Physiology
- Environmental Physiology
Background:
- Laboratory studies indicate aggressive hydration (1-2 L/h) is crucial to prevent hyperthermia and performance decline.
- Field data linking hydration status, core body temperature, and performance in endurance events are scarce.
Purpose of the Study:
- To measure core body temperature (Tcore) in triathletes during a 226 km Ironman triathlon.
- To compare post-event Tcore with hydration status markers.
Main Methods:
- 10 well-trained triathletes participated in the Ironman Western Australia event.
- Core temperature was monitored using ingestible telemetry; body mass, plasma electrolytes, and urine specific gravity were measured pre- and post-race.
Main Results:
- Mean Tcore was 38.1°C; athletes lost 2.3 kg (3.0%) body mass.
- Urine specific gravity increased significantly, indicating dehydration.
- No significant changes in plasma electrolytes were observed.
Conclusions:
- Body mass loss up to 3% was tolerated by triathletes during the Ironman.
- Findings suggest a higher tolerance to hypohydration in field conditions compared to laboratory settings.
- No evidence of thermoregulatory failure was observed despite dehydration markers.
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