In considering the nutrition for maximal sports performance, only the carbohydrate stores are relevant to energy expenditure. During training periods adequate supply of protein is a prerequisite. In competition periods of less than 20 minutes' duration, normal glycogen stores in muscle tissue seem to be adequate, but liver glycogen deficiency can limit the performance via a hypoglycemic effect on the central nervous system. Thus, a carbohydrate-rich diet should be given during the days before and between competition events. With heavy exercise of longer duration it can be of value to increase the glycogen store in muscle groups performing the heaviest work. This is achieved by first depleting muscles of glycogen through exercise and thereafter taking a diet rich in carbohydrate. This regimen also increases the liver glycogen store.