St Laurent, T. G., Todd, M. K., Saunders, M. J., Valentine, R., & Flohr, J. A. (2006). Carbohydrate-protein beverage improves muscle damage and function versus isocarbohydrate and isocaloric carbohydrate-only beverages. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1993.

The purpose of this study was to compare the effects of a carbohydrate/protein beverage consumed during exercise to isocaloric carbohydrate (HI-CHO), isocarbohydrate (LO-CHO), and a non-caloric flavored placebo beverage on post-exercise muscle damage and muscular function. Male cyclists (N = 12) performed four rides to exhaustion on a cycle ergometer at 75% of VO2peak. During the trials, Ss consumed 250 ml of a carbohydrate/protein beverage (7.3% CHO, 1.8% P), an isocaloric carbohydrate beverage (9.1% CHO), an isocarbohydrate beverage (7.3% CHO), or a placebo beverage every 15-minutes until cessation of exercise. Exercise sessions were performed five to ten days apart in a randomly counterbalanced double-blind design. Baseline measures for biomarkers of muscle damage (plasma CK and Mb) and ratings of soreness were obtained before the first exhaustive bout. Post-exercise measures were obtained 6-9 hours (Mb), and 22-24 hours (CK and soreness) following cycling. In addition, post-exercise muscle function was assessed 22-24 hours post-exercise via the number of leg-extension repetitions to fatigue with the right leg at 70% 1 RM.

Post-exercise increases in CK and Mb were significantly higher in the isocaloric carbohydrate, the isocarbohydrate, and placebo conditions compared to the carbohydrate/protein beverage treatment. Significantly more leg-extension repetitions were completed in the muscle function test for the carbohydrate/protein beverage treatment than in the other three conditions. Pre-exercise values for Mb and CK were similar between treatments.

Implication. A carbohydrate-protein beverage consumed during exercise attenuates post-exercise muscle damage, and improves subsequent muscle functioning compared to a placebo, or carbohydrate beverages matched for either carbohydrate or total calories.

Return to Table of Contents for this issue.