Colette, A., & Raynor, H. (2011). Does carbohydrate-protein supplementation enhance endurance performance in male recreational runners? Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 2223.

This study assessed endurance performance effects from different isocaloric (carbohydrate-protein and double-carbohydrate) and isocarbohydrate (carbohydrate-protein and carbohydrate) supplements compared to a placebo during an outside time-trial run. Male recreational runners (N = 12) completed four, 12-mile time-trial runs, 7-10 days apart, at about 75% of race-pace. Dietary intake and physical activity were consistent between each time-trial. Ss were not in a glycogen-depleted state upon entering each time-trial. Weather conditions were consistent among all trials for each S. During each run, Ss consumed a 600 mL drink of one of the four supplements. Supplements were administered in 120 ml servings prior to the start of the time-trial and in four 2.5-mile increments during the time-trials. Endurance performance was measured by time to complete the 12-mile run and time to complete the last 1.2 miles of the run when Ss ran at 100% of race-pace.

A main effect of time occurred during the time-trials for rating of perceived exertion (Borg scale) and heart rate. Perceived exertion significantly increased from the mid-point to completion of the time-trial. Heart rate significantly increased from the start of the run to the start of the maximal effort, and was significantly higher at completion of the effort. No significant difference was found in performance time for the total run or the final 1.2 miles between the supplements.

Implication. The type of carbohydrate and/or protein supplement has no effect on endurance performance in male recreational runners.

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