Time to Exhaustion in Munutes
Carbohydrates are the bodies preferred source of energy during exercise. If intensity is low, the body can burn fat; however, at higher intensities, the body will preferentially use carbohydrates. Because the body has a limited supply of carbohydrates, it is important to maximize this stored fuel prior to racing or competing in a major endurance activity. This study, shows that people that used a “carbo-loading” procedure performed better than those who did not.
This slide summarizes research conducted back in 1967. This research has been replicated in subsequent research of various forms and the results suggest the importance of carbohydrate in the diet for performance.
This study took trained cyclist in what is called a cross-over experimental design. One third of the subjects was placed on a 25% CHO diet, another on a 50% CHO diet, and the final group on a 75% CHO diet for several weeks. At the end of the diet period they were to ride stationary cycles to exhaustion.
The groups were given a couple weeks in between before being placed on one of the other diets. So each cyclist had a chance to be on each diet and performthe test. These are the results of the average of each diet group.
Bergstrom, et.al., (1967). Acta.Physiol.Scand. 71:140-150.