Effect of amino acid mixture intake on physiological responses and rating of perceived exertion during cycling exercise.

This study examined the effects of an amino acid mixture supplement on physiological response and ratings of perceived exertion during submaximal cycle-ergometer exercise in 15 healthy, untrained male students. Subjects performed submaximal sustained exercise (oxygen uptake at anaerobic threshold: 54.6 +/- 12.5% of maximum oxygen uptake capacity) with a cycle-ergometer ride for 60 min. after resting for 1 min. and unloaded cycling for 2 min. They drank either a 380-ml supplement containing vespa amino acids or a lemon-flavored placebo at 30 min. before starting exercise in a double-blind design. The subjects participated in both experiments over a 1-wk. interval. Oxygen uptake, respiratory exchange ratio, heart rate, ratings of perceived exertion, and plasma lactate concentration were measured during the exercise. The change-rate of respiratory exchange ratio for the Supplement group was significantly lower than that for the Placebo group at 10 min. after starting exercise. The change-rate of the ratings of perceived exertion for the Supplement group was significantly lower than that for the Placebo group at 50 min. after starting exercise. There were no significant changes in the rates in oxygen uptake, heart rate, and plasma lactate concentration between groups. We inferred that ingesting the supplement before starting exercise has a significant effect on the respiratory exchange ratio and ratings of perceived exertion during submaximal sustained exercise for 60 min. but not on oxygen uptake, heart rate, and plasma lactate concentration.