Carbohydrate, Muscle Glycogen, and Improved Performance

In brief: Muscle glycogen is the body's chief source of energy for prolonged exercse at moderately high intensity (65% to 85% of Vo2 max); glyocgen reserves therefore limit endurance at this pace. Endurance athletes who train daily must maintain normal glycogen stores to support their training and thereby improve performance. Glycogen synthesis after prolonged exercise is directly related to the amount of dietary carbohydrate; accordingly, athletes who engage in intense daily training should consume 70% of their calories as carbohydrate. Further, athletes can increase their endurance by overloading their glycogen stores. This is done by tapering training the week before a competition and increasing carbohydrate intake the last three days before the event.