Water Water plays two definable roles. First, it helps keep the body cool. Lack of water inhibits this cooling system, and, if enough water is lost, heat cramps, heat exhaustion and even death can result. The second role of water is to help metabolize the chemical reactions in the muscles that produces energy. You cannot rely on your thirst mechanism to alert you when water is needed.
Water is needed long before the thirst mechanism kicks in.
Drink at least 8 ounces of fluid every 15-20 minutes of vigorous exercise. Use a drink that is easily absorbed and be aware that some sport drinks cannot be easily absorbed and may be counterproductive. After a hard session it may take 24 hours to replace water supplies. You need to consume the right food for peak performance. Protein is not stored in the body for use and may be converted to fat.