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Mild hypohydration decreases cycling performance in the heat
Costas N Bardis1, Stavros A Kavouras, Lena Kosti
1Department of Nutrition and Dietetics, Harokopio University, Athens, Greece.
Medicine and Science in Sports and Exercise
|March 9, 2013
Summary
Mild hypohydration (less than 2% body mass loss) impairs cycling performance and increases thermal strain. Even slight dehydration negatively impacts endurance athletes in warm conditions.
Area of Science:
- Exercise Physiology
- Sports Science
- Environmental Physiology
Background:
- Hypohydration exceeding 2% of body mass is known to decrease exercise performance.
- The specific effects of mild hypohydration (less than 2% body mass loss) on performance remain unclear.
Purpose of the Study:
- To investigate the impact of mild hypohydration on cycling performance.
- To assess performance in a simulated-hill circuit course within a warm environment (32.5°C).
Main Methods:
- Ten trained male cyclists completed a simulated cycling circuit under euhydrated (EUH) and hypohydrated (HYP) conditions.
- Hypohydration was induced at -1.0% ± 0.1% of body mass.
- The circuit involved alternating 5 km at 50% max power and 5 km at all-out pace, with rest periods.
Main Results:
- Cycling speed and mean power output were significantly lower in the hypohydrated trial compared to the euhydrated trial.
- Gastrointestinal temperature was elevated in the hypohydrated condition.
- Sweat sensitivity was reduced during hypohydration, while RPE and heart rate remained similar.
Conclusions:
- Mild hypohydration negatively affects cycling performance.
- Increased thermal and cardiovascular strain likely contribute to performance decrements.
- Maintaining hydration is crucial for optimal cycling performance in warm conditions.
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