High-Intensity Intermittent Exercise and Mouth Rinsing: A Systematic Review and Meta-Analysis

Carbohydrate (CHO), caffeine (CAF), and menthol (MEN) mouth rinses are emerging ergogenic aids that may enhance sports performance without the gastrointestinal risks of ingestion. However, there is limited evidence specifically regarding their effects on high-intensity intermittent exercise (HIIE) performance. This systematic review and meta-analysis aimed to evaluate the effect of mouth rinsing on HIIE performance, specifically focusing on solutions containing CHO, CAF, and/or MEN. A comprehensive literature search was conducted using seven databases through June 2025, following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Twenty randomized crossover studies were included. Overall, our meta-analysis revealed no significant improvement in overall HIIE performance following CHO mouth rinse (standardized mean difference = 0.18; 95% confidence interval [-0.10, 0.46]; p = .21), CAF mouth rinse (standardized mean difference = 0.37; 95% confidence interval [-0.02, 0.75]; p = .06), and CHO + CAF combined mouth rinse (standardized mean difference = -0.19; 95% confidence interval [-0.68, 0.30]; p = .44). Subgroup analysis based on HIIE performance outcomes, including power output, total distance covered, and sprint time, also showed no significant differences for any mouth rinse (p > .05). MEN mouth rinse reported no performance benefits in hot environments, despite an improved cooling sensation. While some individual studies suggested improvements-particularly with low glycogen availability or frequent rinsing-the overall evidence does not support mouth rinsing as an ergogenic strategy for HIIE. Further well-controlled research is needed to define optimal rinse type, timing, frequency, and dietary context for HIIE applications.