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 carbohydrate + protein (CHO + PRO) beverage during and/or after endurance exercise improves performance in a subsequent exercise bout compared to CHO alone. Secondly, fluid retention was assessed as a possible mechanism for enhanced performance. Endurance trained subjects (N = 9) received a beverage containing CHO (0.65g of CHO/kg) or CHO + PRO (0.52g of CHO/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 CHO (1.0g of CHO/kg) or CHO + PRO (0.80g of CHO/kg plus 0.20g of protein/kg) immediately post-exercise and at 1 and 4 hours of recovery. Urine volume and body weight were measured post-exercise, during recovery at 3, 5, and 7 hours to calculate fluid retention. Subjects then ran a 10-km time-trial.

There were no statistical differences in 10-km running times or measures of blood glucose or insulin during or after exercise between the four nutritional conditions. However fluid retention was significantly higher at hour 5 of recovery in both conditions in which CHO + PRO was provided when compared to CHO alone conditions.

Implication. While a 4:1 ratio of CHO:PRO provided in recovery enhanced fluid retention compared to CHO alone, there was no accompanying improvement in 10-km running performance. Enhanced fluid retention in recovery does not improve subsequent endurance performance.

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