The base of the diet should come from carbohydrates in the form of starches and sugars. Fluids, especially water, are also important to the winning combination. Dehydration can stop even the finest athlete from playing his or her best game. When starches or sugars are eaten, the body changes them all to glucose, the only form of carbohydrate used directly by muscles for energy. The body uses this glucose in the blood for energy.
Most glucose is stored as glycogen in the liver and muscles.
During exercise glycogen is broken down in the muscles and provides energy. Usually there is enough glycogen in muscles to provide fuel for 90-120 minutes of exercise. Most exercise and sport games do not use up glycogen stores so eating carbohydrates during the activity usually isn't needed. But for some athletes, eating or drinking carbohydrates during exercise helps maintain their blood glucose and energy levels. Instead, focus on getting enough carbohydrates everyday.