Depending on how muscular you are, 55-70% of your body weight is water. Being "hydrated" means maintaining your body's fluid level. When you sweat, you lose water which must be replaced if you want to perform your best. You need to drink fluids before, during and after all workouts and events. Whether you drink water or a sports drink is a matter of choice. If your athletic event lasts for more than 90 minutes, you may benefit from the carbohydrates provided by sports drinks. A sports drink that contains 15-18 grams of carbohydrate in every 8 ounces of fluid should be used. Drinks with a higher carbohydrate content will delay the absorption of water and may cause dehydration, cramps, nausea or diarrhea. There are a variety of sports drinks on the market. Experiment with sports drinks during practice instead of trying them for the first time on the day of an athletic event.