The Effect of Various Carbohydrate Concentrations Mouth Rinsing on Intermittent Running Performance

Endurance exercise performance has been shown to improved with carbohydrate (CHO) mouth rinsing. While multiple studies to elucidate the effectiveness of CHO mouth rinsing continue, most of the studies have utilized 6.4% CHO solutions. The impact of higher CHO concentration on exercise performance remains inconclusive. The aim of this study was to determine the effectiveness of various concentrations of CHO mouth rinse solutions on intermittent running performance. In a double-blind, placebo (PLA) controlled crossover design, 8 recreational endurance runners [age (mean ± SD): 22 ± 1 years; body mass: 62.9 ± 5.9 kg] completed 3 experimental trials. Each trial consisted of standardized breakfast (2 h prior) followed by Yo-Yo Intermittent Recovery Test-Level 1 (Yo-Yo IRT-1) run to exhaustion. Prior the start of the exercise, subjects mouth rinsed with 25 mL of either 6%, 21% CHO and a taste-matched PLA solution for 10 s. Distance covered, level of exhaustion, heart rate (HR), blood glucose, perceived exertion (RPE), perceived arousal scale (FAS) and gastrointestinal scale (GI) were recorded during each trial. There were no significant differences in distance covered (p = 0.07) or level of exhaustion (p = 0.17) between 6%, 21% and PLA trials. There was a significant effect of time on HR (p < 0.001); nevertheless, no significant difference between trials (p = 0.24). There was no difference on blood glucose (p = 0.69) or any of the psychological markers (RPE, p = 0.10; FAS, p = 0.85; GI, p = 0.37). In conclusion, CHO mouth rising with higher solutions concentration of 6% or 21% provide no ergogenic advantage over a PLA solution, and that there was no does-response relationship between solution concentration and Yo-Yo IRT-1 running performance. Further research is warranted to examine the possibility of any dose-response effect of CHO mouth rinse during exercise for more than 30 min.