CARBOHYDRATE-LOADING AND EXERCISE PERFORMANCE - AN UPDATE

This review suggests that there is little or no effect of elevating pr e-exercise muscle glycogen contents above normal resting values on a s ingle exhaustive bout of high-intensity exercise lasting less than 5 m inutes. Nor is there any benefit of increasing starting muscle glycoge n content on moderate-intensity running or cycling lasting 60 to 90 mi nutes. In such exercise substantial quantities of glycogen remain in t he working muscles at the end of exercise. However, elevated starting muscle glycogen content will postpone fatigue by approximate to 20% in endurance events lasting more than 90 minutes. During this type of ex ercise, exhaustion usually coincides with critically low (25 mmol/kg w et weight) muscle glycogen contents, suggesting the supply of energy f rom glycogen utilisation cannot be replaced by an increased oxidation of blood glucose. Glycogen supercompensation may also improve enduranc e performance in which a set distance is covered as quickly as possibl e. In such exercise, high carbohydrate diets have been reported to imp rove performance by 2 to 3%.