Mattern, C. O., Campbell, B., Carson, T., Charland, J., Craven, S., Filip, N., Watt, C., Yaple, R., & Heidi, B. K. (2012). The addition of protein to a carbohydrate supplement enhances fluid retention but not running performance. Presentation 2356 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study determined if a protein+carbohydrate beverage during and/or after endurance exercise improved performance in a subsequent exercise bout compared to carbohydrate alone. It also measured fluid retention as a possible mechanism for enhanced performance. Endurance-trained Ss (N = 9) received a beverage containing carbohydrate (0.65g of carbohydrate/kg) or protein+carbohydrate (0.52g of carbohydrate/kg plus 0.13g of protein/kg) during a one-hour run at 68% of VO2max. During a 7-hour recovery period, Ss then received beverages containing either carbohydrate (1.0g of carbohydrate/kg) or protein+carbohydrate (0.80g of carbohydrate/kg plus 0.20g of protein/kg) immediately post-exercise and at one and four hours of recovery. Urine volume and body weight were measured post-exercise, during recovery at hours 3, 5, and 7 to calculate fluid retention. Ss then ran a 10-km time-trial.

There were no statistical differences in 10-km running times, measures of blood glucose, or insulin during or after exercise among the four nutritional conditions. However, fluid retention was significantly higher at hour 5 of recovery in both conditions in which protein+carbohydrate was provided during recovery as compared to those in which carbohydrate alone was given.

Implication. A 4:1 ratio of carbohydrate to protein provided in recovery enhanced fluid retention compared to carbohydrate alone. It did not lead to improved 10-km running performance.

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