Carbohydrate mouth rinse enhances time to exhaustion of running performance among dehydrated subjects

Abstract

Mouth rinsing with carbohydrate (CHO) solution can effectively enhance endurance performance by stimulating areas of the brain that are related to arousal and motivation. It remains unclear whether the effectiveness of CHO mouth rinsing is influenced by the level of hydration. Hence, this study was conducted to examine the effect of mouth rinsing a CHO solution on the running performance among dehydrated subjects. Twelve well-trained subjects (age: 21 ± 1 years; stature: 170.8 ± 3.5 cm; weight: 58.5 ± 3.5 kg; VO2max: 58.3 ± 3.3 mL.kg−1.min−1) completed two sub-maximal running exercises at an intensity 70% VO2 max until exhaustion while in a dehydrated state (2% body weight deficit). During the run, participants had mouth rinsed 25 mL of either a 6% CHO solution or placebo (PLA) at 15 min intervals. Plasma glucose (Pglu), plasma lactate (Plac) and psychological measures were sampled intermittently during the exercises. Gas exchange, perceived exertion (RER), heart rate (HR), mean skin temperature (Tsk) and rectal temperature (Tr) were recorded during trials. The running time to exhaustion (TTE) was significantly (p = 0.000) shorter when mouth rinsing a PLA (76.8 ± 3.9 min) solution as compared to that when rinsing with a CHO solution (81.2 ± 4.1 min). There was no significant effect on the metabolic, psychological, thermoregulatory and cardiovascular variables between the two trials. This study demonstrated that participants in a dehydrated state were able to enhance their performance when they rinsed their mouth using a CHO solution as against a PLA.