A Study to Understand the Analgesic Properties of Topically Applied Menthol When Used in a Marathon.

This is a real-world, observational study evaluating self-selected use of topically applied menthol among runners in the 2025 Chicago Marathon. Participants independently choose whether to use topically applied menthol products, which products to use, and how frequently to apply them as part of their usual pain-management behaviour. The study does not assign or administer any intervention. Data are collected from participants who voluntarily used topically applied menthol and chose to complete the questionnaires. Participants may self-select to use topically applied menthol products during the race or recovery as they normally would. Researchers do not assign or direct product use. Product application occurs independently of study participation.