Cathcart, A. J., Murgatroyd, S. R., McNab, A., Whyte, L. J., & Easton, C. (2008). The thermoregulatory effect of consuming a beverage containing protein during exercise. ACSM 55th Annual Meeting Indianapolis, Presentation Number 835.

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This study determined the effect of consuming a standard CHO-electrolyte beverage containing a small quantity of protein during eight days of strenuous competition in a hot environment. Competitors (N = 28) in the TransAlp mountain bike stage race (~ 35C) were assigned to fitness matched placebo (CHO-electrolyte supplement) or protein (protein plus CHO-electrolyte supplement) groups based on predicted VO2peak. Less than one hour before and after each stage, core temperature, urine osmolality, and creatine kinase concentration were measured. Heart rates throughout the competition and performance were recorded.

Supplement consumption was significantly higher in the protein-added group. There was no significant difference in creatine kinase between groups before the event. Creatine kinase was substantially elevated during the race, the rise being similar between groups. Both groups commenced the race with similar urine osmolalities which increased significantly throughout the race although the rise was significantly more in the protein-added group. Core temperature was similar between groups prior to the race but was significantly lower post-exercise and throughout the race in the protein-added group. Total race time was significantly shorter in protein-added group.

Implication. Despite no effect on muscle damage, the addition of protein to a standard carbohydrate-electrolyte beverage enhanced fluid retention, reduced thermal strain, and improved exercise performance in the heat.

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