Water is the most important, yet over-looked, nutrient by athletes. Water and fluids are essential to maintaining good hydration and body temperature. Sweat losses to keep the body cool can exceed several liters in a 1-hour period. Adolescents and adults should replace any lost body weight lost during a exercise with equal amounts of fluids. A good indication that you have fully rehydrated is to check to see if your urine is clear.
Cool water is the best choice.
Drink plenty of water, juice and milk. Avoid caffeine containing beverages. Caffeine is a diuretic and promotes fluid loss. Drink plenty of fluid before, during, and after exercise. Changing body weight to improve performance must be done safely and effectively or it may do more harm than good.