Welikonich, M. J., Nagle, E. F., Goss, F. L., Robertson, R. J., & Crawford, K. (2011). Effect of carbohydrate-protein supplementation on resistance exercise performance, perceived exertion, and salivary cortisol. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 2216.

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This study determined the effect of carbohydrate and protein versus carbohydrate supplementation and a placebo on resistance exercise performance, perceived exertion, and post-exercise salivary cortisol in healthy recreationally-trained males (N = 27). Ss randomly received 1) carbohydrate and protein; 2) carbohydrate; or 3) a placebo supplement 15 minutes prior to, between every other set, and immediately following resistance exercise. The carbohydrate and protein and carbohydrate supplements were of equal fluid volume and isocaloric. The resistance exercise session consisted of a seated leg-press exercise beginning with 1 set of 10 repetitions at 40, 50, and 60% of 1 RM, continuing with multiple sets of 8 to 10 repetitions at 70% of 1 RM until fatigue. Ratings of perceived exertion for the active muscle group and overall body were measured immediately following each set and Session-RPE was measured 30 minutes following the exercise session. Salivary cortisol samples were collected 15 minutes before and 30 minutes following the resistance exercises.

Carbohydrate and protein and carbohydrate supplementation resulted in a significantly greater total number of repetitions performed to fatigue than a placebo. Carbohydrate supplementation resulted in reduced post-exercise salivary cortisol and ratings of perceived exertion of the active muscles at 25% and 50% of total volume of work performed compared to carbohydrate and protein supplementation or a placebo.

Implication. Carbohydrate and protein and carbohydrate supplementations before and during resistance exercise can have an immediate beneficial performance effect.

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