Date Approved


Degree Type

Open Access Senior Honors Thesis

Department or School

Health Sciences

First Advisor

John Carbone, PhD, RD

Second Advisor

Colleen Croxall, PhD

Third Advisor

Ann R. Eisenberg, PhD


Background: L-menthol is an emerging athletic performance-enhancing aid. This review serves as an analytic report of existing controlled trials in the scientific literature that have investigated this compound as a sports aid when administered via the novel method of mouth rinsing followed by expectoration. Methods: Data on menthol mouth rinsing was sourced from EBSCO PowerSearch, Medline, and NCBI. In addition to a systematic review of existing literature, the current review outlines a detailed protocol to evaluate menthol mouth rinsing on a treadmill time-to-exhaustion test. This protocol adds an additional feature of conducting blood work examining any changes in energy substrate availability subsequent to menthol mouth swirling. It will also provide further investigation on whether a pre-exercise mouth rinse administration is sufficient to elicit an ergogenic response, which could then be compared to protocols that implemented more frequent mouth rinsing intervals. Results: Nine controlled trials involving menthol mouth rinsing were found. Data showed that menthol mouth rinsing could provide ergogenic effects when used in heated environments by non-heat acclimated individuals. What exactly causes these ergogenic effects is still not fully known, but it is predicted that menthol activates and then desensitizes ion channels in the mouth known as Transient Receptor Potential Cation Channel Subfamily M Member 8 (TRPM8) that subsequently result in a feeling of coolness, while also reducing thermal discomfort and improving breathing comfort. It is still inconclusive whether administration is best prior to exercise, at different intervals throughout an activity, in the latter stages of exercise, or a combination of all. Conclusion: L-menthol is a promising ergogenic aid and swirling it might provide a practical aid for athletes that train and compete in heated environments