ABSTRACT
Water is one of the most important nutrients for anyone who exercises or participates in sports, and it assumes even greater importance during the exercise/sport session. Exercise performance is impaired if normal body weight decreases by as little as 2 to 3% as lost water, and greater losses lead to serious physiological changes and death. Thirst usually prompts us to drink enough water to meet our daily needs. When exercising, however, water losses are greater than normal and the sensation of thirst is blunted, so that we must deliberately rehydrate by following a water replacement regimen. Despite the essential nature of water, there is a range of optimum intake which if exceeded can result in water toxicity. Fortunately, water intoxication, which is usually associated with deliberate overconsumption by ultraendurance athletes, is rare and is usually quickly resolved.
