Sweat rates during international open water competitions and the importance of feedings ineliteswimmers

Open water swimming is an outdoor discipline with different environmental characteristics that affect athletes. The aim of this work was to know the sweat rate during a 5 km and 10 km OWS in elite swimmers in different water temperatures and analyze hydration before competition. A total of 45 elite swimmers (22 females and 23 males) were analyzed during an international event over 5 or 10 km in different water temperature. Sweat rate (L·h−1), percentage of weight loss and drink ingestion (L) were measured. ANOVA test indicatesthe significance of the difference. The results showed that warm water on 10 k sweat rate is statistically significant (p < 0.001) (-1.99 ± 0.34vs -1.14 ± 0.36 vs -1.48 ± 0.49 L·h−1), and in cold water with wetsuit, weight loss (p < 0.05) and drink ingestion (p < 0.001) are significant too (-2.27 ± 0.75 %; 1.31 ± 0.63 L). The results show a higher sweat rate in warm water and weight loss with wetsuit, drink ingestion is lower in cold water. This study confirms that it is important to analyze the environmental characteristics of an open water swimming competition to plan a specific hydration protocol to get the best performance.