Recent research from our lab suggests that alanine supplementation, with or without carbohydrate, promotes a favorable metabolic shift that could theoretically enhance long-term exercise performance.
PURPOSE: The purpose of this study was to explore the metabolic and potential ergogenic effects of alanine supplementation along with carbohydrate during cycling in endurance athletes.
METHODS: The effects of consuming a beverage containing 3% L-alanine plus 3% sucrose (ALA) were compared to those of an artificially flavored and sweetened, non-caloric placebo beverage (PLC) using a double-blind, randomized, cross-over approach. Twelve (nine male and three female) trained athletes 18 to 44 years of age were recruited. Participants cycled on an electronically-braked ergometer at 65% VO2max for 60 min immediately followed by completion of a pre-determined amount of work (J=0.65 x Wmax x 3600) for time to determine performance. Thirty minutes prior to exercise 500 ml of the trial beverage were ingested, and 250 mL were consumed every 15 minutes throughout the trial. Blood samples were obtained at fasting, at the end of the standardized submaximal exercise period, and upon completion of the trial. Subjects returned six to ten days later to complete the same protocol while ingesting the other beverage. Plasma concentrations of free fatty acids (FFA), 3-hydroxybutrate (3-HB), glucose, and lactate were assessed at each timepoint.
A paired t-test was used to determine potential difference in time to complete work and a 2x3 ANOVA with post hoc paired t-tests were used to assess differences among plasma substrates.
RESULTS: Time to complete work was similar (p>0.05) between trials (ALA: 71.7±8.7 min; PLC: 67.6±7.8 min). Concentrations of FFA and 3-HB after the submaximal period and after the performance trial were higher (p<0.05) during the PLC trial than the ALA trial. Plasma glucose and lactate concentrations did not differ between trials.
CONCLUSION: Despite not affecting performance, L-alanine plus carbohydrate produced positive metabolic effects suggesting the potential to preserve endogenous energy sources during endurance exercise. Further investigation is warranted on the minimal dose of alanine required to elicit metabolic changes and conditions under which exercise performance may be improved.