Zhu et al. 2026, Effects of different menthol administration routes on endurance performance and physiological responses in the heat — a network meta-analysis

Network meta-analysis (Frontiers in Nutrition 13:1833420) comparing menthol delivery routes — mouth rinse, ingestion and topical — for exercise in the heat (≥25 °C). For endurance performance (13 studies, 272 participants) ingestion ranked highest by surface-under-the-curve (SUCRA 76%), ahead of topical and mouth rinse, but every route’s effect was modest and non-significant (e.g. ingestion vs control SMD 0.20; 95% CI −0.48 to 0.88). Core temperature and heart rate barely moved on any route. Relative humidity was the key moderator: a robust ergogenic signal appeared below 50% humidity but was markedly attenuated at ≥50%, consistent with menthol’s effect being perceptual rather than a true cooling of the body. The authors rate the evidence low-to-very-low certainty (GRADE), call the route rankings exploratory rather than definitive, and warn that menthol decouples perceived from actual heat strain, so it must never replace genuine cooling or physiological monitoring.