Moore, R. W., Saunders, M. J., Pratt, C. A., Hammer, M. C., Lehman, K. L., Todd, M. K., Flohr, J. A., & Kies, A. K. (2007). Improved time to exhaustion with carbohydrate-protein hydrolysate beverage. ACSM Annual Meeting New Orleans, Presentation Number, 904.

This study attempted to: 1) determine if time-to-exhaustion during a simulated endurance duathlon was improved with the ingestion of carbohydrate-protein hydrolysate beverages, compared to a carbohydrate beverage, and 2) determine if varied concentrations of protein hydrolysate in carbohydrate-protein beverages influenced time-to-exhaustion. Recreationally-competitive male cyclists/runners (N = 10) completed a simulated duathlon comprising an 8 km treadmill run at 80%VO2max, simulated 50 km cycle at 70%VO2max, and subsequent treadmill run at 80%VO2max until volitional exhaustion. At 5 km intervals during the cycle segment, Ss consumed a total of 1.5 liters of carbohydrate (6%), carbohydrate plus protein (6% CHO + 1.2% casein protein hydrolysate) or carbohydrate plus protein hydrolysate (6% CHO + 2.4% protein hydrolysate). Ss completed three simulated duathlons (one for each treatment). Trials were separated by 7-14 days.

Time-to-exhaustion in the final run segment was significantly longer in trials utilizing protein hydrolysate beverages compared to carbohydrate alone. There was no significant difference in time-to-exhaustion between the two protein treatments. No significant treatment-effects or treatment x time interactions were observed in physiological variables (lactate, glucose, heart rate, VO2, ventilation, RER and RPE) between trials.

Implication. The addition of protein hydrolysate to a 6% carbohydrate beverage significantly improved time-to-exhaustion during a simulated endurance duathlon. However, no further improvements were observed between two different carbohydrate plus protein beverages, suggesting that protein levels >2% are unnecessary for optimal endurance benefits when beverages are consumed during exercise.

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