Should Ultra-Runners drink to thirst? study tests hydration advice

This study aimed to find out if drinking only when thirsty is a safe and effective hydration strategy for runners in an extreme, multi-day mountain race. Researchers followed 198 participants of the 2015 Ultra Trail du Mont-Blanc, comparing their blood sodium levels, weight changes, and symptoms based on whether they drank when thirsty or followed a pre-set schedule. The goal was to gather evidence to help athletes avoid dangerous electrolyte imbalances and improve race performance.