Performance is affected by dehydration with some studies saying that even a 2% dehydration, expressed as body mass loss, is enough to alter performance negatively.
A recent study analysed the effects of hydration and cooling on performance during the Doha 2019 World Athletics Championships, held in hot and humid conditions.
To do so they surveyed the hydration and cooling strategies, body mass loss, and core and skin temperatures of 83 elite athletes.
- 93% of endurance athletes had a drinking strategy, which included water (85%), electrolytes (83%) and carbohydrates (81%).
- 80% of athletes planned pre-cooling, mainly using ice vests (53%) and cold towels (45%).
- 93% of athletes used mid-cooling, mainly head/face water dousing (65%) and cold-water ingestion (52%).
- Less common cooling interventions were ice slurry ingestion and menthol-based interventions.
- Relative body mass loss was higher in men than women (-2.8% vs -1.3%), and not associated with performance outcome.
- DNF had a higher pre-race skin temperature (33.8°C vs 32.6°C in finishers).
- Within finishers a lower pre-race skin temperature was moderately associated with faster race completion.
- Most athletes had a pre-planned drinking strategy, based mainly on personal experience.
- Pre-race temperature management, including skin temperature, is important for endurance exercise in hot-humid conditions.
In hot conditions hydrate properly and keep your temperature low to improve your performance and chances of finishing a race.
Hydration and cooling in elite athletes: relationship with performance, body mass loss and body temperatures during the Doha 2019 IAAF World Athletics Championships. Racinais S, Ihsan M, Taylor L, et al. British Journal of Sports Medicine 2021;55:1335-1341.