ABSTRACT
Muscle activity during exercise generates significant heat production creating a challenge for the body’s temperature regulating system even under mild conditions. Because sweat evaporation is the primary method for humans to cool the body, athletes can lose significant amounts of water during exercise. Fluid losses vary greatly across different sports and among individual athletes, ranging from 0.5 to 2.6 L/h. Sweat losses are even greater when exercise is performed in hot and humid conditions. Depending on the magnitude of the sweating response and drinking behavior of the athlete, fluid imbalances such as dehydration and hyponatremia can develop, leading to poor performance, increased risks of heat exhaustion, heatstroke, and in extreme circumstances, brain damage or even death.
