ABSTRACT
For many years the importance of carbohydrates as substrates for contracting skeletal muscle has been recognized (Christensen and Hansen, 1939a and 1939b; Krogh and Lindhard, 1920), the classical studies of Christensen and Hansen in the 1930s clearly demonstrating the importance of carbohydrate availability during prolonged exercise and the potential influence of dietary carbohydrate on endurance exercise performance. Their work was expanded in the late 1960s with the use of the percutaneous muscle biopsy technique to examine skeletal muscle glycogen metabolism during exercise in human volunteers (Bergstrom and Hultman, 1967; Bergstrom et al., 1967; Hermansen et al., 1967). These studies demonstrated the critical role of muscle glycogen as a determinant of endurance exercise performance and the benefit of increasing dietary carbohydrate intake prior to prolonged exercise. Since that time, numerous studies have been undertaken and there is little doubt that adequate carbohydrate availability is essential for heavy training and successful athletic performance (Costill, 1988).
