Carbohydrate ingestion during exercise: effects on muscle glycogen resynthesis after exercise.

To determine the effect of carbohydrate feeding on muscle glycogen resynthesis, 8 male cyclists pedaled for 2 hrs on a cycle ergometer at 70% of VO2max while consuming either a 10% carbohydrate solution (CHO) or a nonnutritive sweet placebo (No CHO). Muscle biopsies were obtained from the vastus lateralis prior to, immediately postexercise, and at 2, 4, and 24 hrs of recovery. Blood samples were taken before and at the end of exercise, and at specified times during recovery. During both trials food intake was withheld for the first 2 hrs of recovery, but at 2 hrs postexercise a 24% carbohydrate solution was ingested. The rate of muscle glycogen resynthesis during the first 2 hrs of recovery was similar for the CHO and No CHO trials. Following ingestion of the 24% carbohydrate supplement, the rates of muscle glycogen resynthesis increased similarly in both trials. These similar rates of resynthesis following ingestion of the carbohydrate supplement were obtained despite significantly greater serum glucose and insulin levels during the No CHO trial. The results indicate that the carbohydrate feedings taken during exercise had little effect on postexercise muscle glycogen resynthesis.