Hydration
Water is the most important nutrient for athletes. Water comprises about 60% of body weight and is essential for almost every bodily function. Because your body cannot make or store water, you must replace the water that you lose in your urine and sweat.
Everyone should drink at least two quarts (64 oz.) of water each day—and athletes need even more. To stay hydrated and avoid overheating, drink plenty of fluids before, during, and after sports or exercise. When you work out or compete, especially in hot weather, try to replace the amount of water you lose in sweat by drinking the same amount of fluid.
Drinking cool water is the best way to keep hydrated during workouts or events that last an hour or less. Sports drinks made up of 6% to 10% carbohydrates can help you stay hydrated during longer events. Most sports drinks should be diluted with approximately 50% water.
Because thirst is not a reliable way to tell if you need water, be sure to drink even if you are not thirsty. You will not start feeling thirsty until you have already lost about 2% of your body weight—enough to hurt performance. Also, if you stop drinking water as soon as your thirst is satisfied you will get only about half the amount you really need.