How eating carbohydrates affects energy use and breakdown during long exercise

Ingesting a 10% carbohydrate drink at 500 ml/h led to a significant increase in total glucose appearance in endurance-trained cyclists during a 180-minute ride.

• Total carbohydrate oxidation was similar between the carbohydrate drink and placebo groups.
• Total glucose appearance increased significantly during exercise in both groups, but plateaued at 75 minutes in the carbohydrate drink group.
• At the end of exercise, glucose appearance was significantly greater in the carbohydrate drink group compared to the placebo group.
• Blood glucose oxidation also increased significantly and was higher in the carbohydrate drink group at the end of exercise.
• Mean endogenous glucose appearance was significantly lower in the carbohydrate drink group throughout the trial.
• Muscle glycogen utilization was identical in both groups and was higher during the first hour of exercise.

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