Effects of carbohydrate, caffeine and menthol mouth rinses on exercise performance and ratings of perceived exertion: a systematic review and network meta-analysis.

BACKGROUND: Mouth rinsing with carbohydrate (CHO), caffeine (CAF), or menthol (MEN) is a non-ingestive strategy that may enhance exercise performance and alter ratings of perceived exertion (RPE), but findings remain inconsistent. This systematic review and network meta-analysis (NMA) compared their relative effects. METHODS: This prospectively registered review (PROSPERO CRD420261282363) followed PRISMA-NMA. PubMed, Embase, Web of Science, the Cochrane Library, and SPORTDiscus were searched to 3 April 2026. Randomized controlled and crossover trials were eligible. RoB 2 and Confidence in Network Meta-Analysis (CINeMA) were used to assess risk of bias and certainty of evidence. Pairwise and network meta-analyses were performed in Stata 18.0, effects were expressed as standardized mean differences (SMDs), and rankings were based on the surface under the cumulative ranking curve (SUCRA). RESULTS: Fifty-seven studies involving 609 participants were included. The evidence base primarily comprised trained or physically active individuals, and the exercise protocols predominantly involved cycling- or running-based endurance tasks. CAF ranked first for time to exhaustion (SUCRA = 85.1%), work done during a fixed-time test (83.4%), and RPE (74.0%). MEN ranked first for time to complete a fixed amount of work (79.8%) and mean power (77.3%), whereas CHO ranked second across all five outcomes. The NMA showed no statistically significant differences among CHO, CAF, and MEN. Compared with placebo (PLA), CAF (SMD = 0.57, 95% CI: 0.13, 1.01) and CHO (SMD = 0.43, 95% CI: 0.11, 0.75) significantly prolonged time to exhaustion. CAF (SMD = 0.48, 95% CI: 0.11, 0.86) and CHO (SMD = 0.36, 95% CI: 0.12, 0.60) also significantly increased work done during a fixed-time test. CHO significantly reduced RPE (SMD = -0.14, 95% CI: -0.26, -0.02). No significant effects relative to PLA were observed for time to complete a fixed amount of work or mean power. CONCLUSION: The relative advantages appeared outcome-specific. CAF showed the most favorable ranking trends for fatigue tolerance, sustained output, and RPE, whereas MEN ranked highest for completion efficiency and mean power. Because CHO, CAF, and MEN did not differ significantly, these rankings should be interpreted probabilistically rather than as evidence of clear superiority. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261282363, identifier CRD420261282363.