Mouth rinsing with branched‐chain amino acids and carbohydrates on steady‐state metabolism, exercise performance, and the endocrine responses to exercise (634.6)

Abstract

Previous research suggests that mouth rinsing carbohydrates (CHO) improves exercise performance. The mechanisms for the improvement are not yet known, but may involve maintenance of insulin concentrations during exercise or attenuation of centrally‐mediated fatigue from putative, caloric‐responsive receptors in the oral cavity. The purpose of this study was to determine the effects of mouth rinsing branched‐chain amino acids (BCAA) or CHO on cycle time trial performance, blood markers of central fatigue (prolactin), plasma insulin, glucose, and lactate concentrations, substrate oxidation during steady‐state exercise, and the subjective exercise experience. Ten healthy, endurance‐trained adult males (23.5 ± 3.8 y, 74.0 ± 9.0 kg, 180.5 ± 5.4 cm, 57.9 ± 6.9 ml/kg/min VO2 peak) volunteered for the study. Participants exercised at 65% Wattmax for 30 min then completed a time trial equivalent to 30 min cycling at 75% Wattmax. Participants rinsed the mouth with 6% glucose (CHO), 6% branched‐chain amino acids (BCAA), or water (PLA) for 10 s at the start and after every 10 min during the steady‐state exercise and cycle time trial. Treatment did not affect heart rate, ratings of perceived exertion, affect, arousal, plasma glucose and lactate concentrations, and substrate oxidation during steady‐state exercise and a cycle time trial. Furthermore, mouth rinsing BCAA or CHO did not affect plasma insulin or prolactin concentrations during steady‐state exercise or a cycle time trial. Finally, mouth rinsing BCAA or CHO did not affect cycle time trial performance after steady‐state exercise. In conclusion, mouth rinsing BCAA or CHO does not improve cycle time trial lasting approximately 30 min when performed after 30 min steady‐state exercise.