The effects of carbohydrate caffeine mouth rinsing on indices of power output during repeated supra-maximal cycling

Carbohydrate–caffeine mouth rinsing has been shown to rapidly improve peak power production (Beaven et al., 2013, Journal of Applied Physiology, Nutrition and Metabolism, 6, 633–637). The purpose of the current research was to investigate if carbohydrate–caffeine mouth rinsing increased power output during repeated supra-maximal cycling. Ten recreationally active males (mean ± s: age: 26 ± 4 years, body mass: 81.7 ± 12.1 kg and height: 180 ± 6 cm) were recruited following ethical approval. Participants completed three exercise trials in a randomised, double-blind cross-over design where they were exposed to either a no rinse (control), placebo rinse solution or a carbohydrate–caffeine solution. Exercise trials comprised 4 × 15 s Wingate tests interspersed with 4 min of active recovery. Resistance in each Wingate was set at 0.7 Nm · kg−1 of body weight. About 25 ml of solution containing either 1.6 g of maltodextrin plus 70 mg of anhydrous caffeine or a non-caloric placebo solution was rinsed for 20 s in the oral cavity immediately before each sprint, and power output measures were recorded. Compared to the placebo condition, the carbohydrate–caffeine mouth rinse had no significant difference on peak power (P = 0.588), mean power (P = 1.0), revolutions per minute maximum (P = 0.486), or total work (P = 1.0). However, total work following the carbohydrate–caffeine rinse was significantly higher than the no-rinse control (11667 ± 2048 J, 11289 ± 1973 J; P = 0.012). Magnitude-based inferences identified carbohydrate–caffeine mouth rinsing had a small positive overall effect on peak power compared to placebo (d = 0.37; 95% CL = 15–57 W), and a moderate positive effect on peak power compared to control (d = 0.71; 95% CL = 15–84 W). A novel finding from the current study suggests that the act of mouth rinsing may elicit an ergogenic effect on supra-maximal exercise performance in comparison with not rinsing at all; however, no significant difference was observed when comparing a carbohydrate–caffeine mouth rinse and a non-caloric placebo. This may indicate that previous mouth rinse literature, which failed to incorporate a no-rinse condition, may have underestimated the role of the placebo effect associated with the act of mouth rinsing. More research is required to separate the placebo and true physiological effects of carbohydrate–caffeine mouth rinsing given the reported improvement in supra-maximal exercise performance.