GLOSSARY

Hydration and Performance concerns water status and task performance, with effects dependent on the task and conditions.

Effects depend on the size and speed of the deficit, heat, duration and task. Prolonged endurance in heat is often more vulnerable, whereas strength, skill and cognitive outcomes vary. A single percentage is not a universal cliff at which every athlete's performance suddenly deteriorates. Sleep, fueling, illness and training fatigue also matter when interpreting a slower time or an unsuccessful training session.

Reduced body water can increase cardiovascular and heat-dissipation demands, especially during prolonged hot exercise. Adequate hydration does not guarantee protection against heat illness; intensity, acclimation and environment still matter. Not every performance decline or temperature rise is caused solely by dehydration. Continuing to drink should never substitute for recognizing excessive strain, reducing exposure and obtaining appropriate assessment when warning signs occur.

During exercise, coordinate drinking opportunities and fueling with estimated losses and gut tolerance. Replacing every drop of sweat immediately is not compulsory, and gaining mass from excessive drinking is undesirable. The strategy should adapt to weather and intensity. When access is constrained, rehearsing its practical execution matters as much as calculating volumes. A plan supports decisions rather than forcing intake despite changing conditions.