Influence of carbohydrate mouth rinsing on repeated interval swimming performance in well-trained adolescent swimmers

Background: Carbohydrate mouth rinsing (CHO-MR) may provide an ergogenic effect for exercise performance, with small beneficial effects demonstrated in cycling and running exercise ≤ 1 hour. There is little evidence supporting the use of CHO-MR during high-intensity intermittent activity such as some swimming disciplines. As such, the aim of this study was to explore the impact of CHO-MR on sprint time, perceptions of effort and arousal, and gastrointestinal comfort in well-trained adolescent swimmers. Eleven participants completed three trials (CHO-MR, placebo and control) in a randomised, double-blinded fashion. Participants were fasted and completed four 50m sprints separated by 30-seconds rest, with rinsing occurring prior to each sprint. Results: There were no significant differences between conditions for fastest (CHO: 29.7 ± 3.3 s; PLA: 30.0 ± 3.2 s; CON: 29.3 ± 3.2 s), mean (CHO: 31.4 ± 3.0 s; PLA: 31.4 ± 2.8 s; CON: 30.8 ± 2.6 s), total sprint time (CHO: 125.5 ± 12.2 s; PLA: 125.5 ± 11.4 s; CON: 123.3 ± 10.5 s) or percentage decrement score (CHO: 5.8 ± 4.2%; PLA: 4.9 ± 4.2%; CON: 5.7 ± 4.7%). Furthermore, no significant differences between conditions were observed for rate of perceived exertion, arousal, or gastrointestinal comfort. Conclusion: The results of this study do not support the use of CHO-MR as an ergogenic aid for repeated interval swimming. Future research could explore the impact of CHO-MR on longer duration swimming given the potential ergogenic effect in other disciplines.