Improved Time To Exhaustion With Carbohydrate-Protein Hydrolysate Beverage

Abstract

PURPOSE: Increased carbohydrate content in sports beverages improves time to exhaustion (TTE), up to concentrations ranging between 6–10%. Recent studies show that co-ingestion of carbohydrate-protein elicits further improvements in TTE versus carbohydrate alone, but no studies have examined the effects of varying protein content in carbohydrate-protein beverages on TTE. The purposes of this study were to: 1) determine if TTE during a simulated endurance duathlon was improved with 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 TTE. METHODS: Ten recreational ly-competitive male cyclists/runners (VO2max=54.3±7.1 mL·kg-1·min-1) completed a simulated duathlon, which consisted of an 8km treadmill run at 80% VO2max, simulated 50km cycle at 70% VO2max, and subsequent treadmill run at 80%VO2max until volitional exhaustion. At 5km intervals during the cycle segment, subjects consumed a total of 1.5L of carbohydrate (CHO; 6%), CHO+P (6% CHO + 1.2% casein protein hydrolysate; PeptoPro®) or CHO+PP (6% CHO + 2.4% protein hydrolysate). Subjects completed three simulated duathlons (one for each treatment) in a randomly-assigned, double-blind protocol. Repeat trials were separated by 7–14 days. RESULTS: TTE in the final run segment was significantly longer (p<.05) in trials utilizing protein hydrolysate beverages (15.9±7.5min) compared to CHO (13.0±8.3min). There was no significant difference in TTE between CHO+P (17.5±8. 7min) and CHO+PP (14.2±7.9min) treatments. No significant treatment-effects or treatment*time interactions were observed in physiological variables (lactate, glucose, heart rate, VO2, ventilation, RER and RPE) between trials. CONCLUSIONS: Addition of protein hydrolysate to a 6% carbohydrate beverage significantly improved TTE during a simulated endurance duathlon. However, no further improvements were observed between CHO+P and CHO+PP beverages, suggesting that protein levels >2% are not necessary for optimal endurance benefits when CHO+P beverages are consumed during exercise. Supported by a research grant from DSM Food Specialties, Inc.