Seifert, J. G., Schapman, J., Little, T. J., Robins, A., Thompson, D. G., & Portman, R. (2009). Gastric emptying characteristics of carbohydrate/protein and carbohydrate only sports drinks during moderate intensity exercise. ACSM 56th Annual Meeting, Seattle, Washington. Presentation number 1977.

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This study compared the gastric emptying rate of a carbohydrate-protein sports drink to a carbohydrate sports drink during moderate intensity, steady state exercise. Ss (N = 12) cycled for 60 minutes at 65%VO2max while ingesting 300 ml of either a 6% carbohydrate plus 1.5% protein sports drink or a 6% carbohydrate only sports drink. Each drink contained 100 mg 13C labeled-NaC2H3O2 to serially assess gastric emptying. Beverage ingestion occurred following a 10-minute warm-up and 13 minutes of steady state exercise. 13CO2 was then collected every five minutes over 45 minutes after ingestion. Venous blood glucose, heart rate, and rating of perceived exertion were collected at 15-minute intervals during exercise.

There were no differences between treatments in gastric emptying, blood glucose, heart rate, or rating of perceived exertion. Gastric emptying peaked approximately 25 minutes after beverage ingestion for both treatments.

Implication. Carbohydrate-protein sports drinks have similar gastric emptying characteristics during exercise to that of a carbohydrate sports drink.

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