Mechanisms through which menthol acts on human temperature regulation and perception, and possible effects on muscle function.

Menthol is one of the world’s most widely used flavors and fragrances, and owing to its cooling and analgesic properties, it has long been used to alleviate symptoms arising from a number of maladies, from the common cold to musculoskeletal pain. More recently, menthol has been used as an ergogenic aid to alter perception and performance, and as part of an approach for studying the physical basis of temperature sensation and thermoregulatory function in humans. The purpose of this opening presentation is first to review the mechanisms whereby menthol is thought to exert its influence, and second, to explore its influence on muscle function per se. Specifically, Part One of this presentation will explore possible mechanisms through which menthol acts on human temperature regulation and perception. This will include an overview of what menthol is, and common uses. A more general review of the physical basis of human thermosensitivity will follow, with emphasis on the family of temperature-activated Transient Receptor Potential (TRP) ion channels, focusing on the TRP Melastatin 8 (TRPM8) ion channel and its interaction with menthol in primary sensory neurons. The afferent pathways and central sites of integration arising from menthol exposure will be reviewed, along with the associated perceptual and thermophysiological responses. Various factors thought to influence menthol’s forcing function when taken orally or topically will also be presented. Part Two of this presentation will explore the possible influence menthol exerts on muscle function when applied topically. Specifically, menthol’s possible influence on recovery of muscle soreness and gross measures of physical performance following exercise-induced muscle will be reviewed, along with its acute influence on muscular strength, power, and joint range of motion. Attendees will be given a comprehensive overview of current research in this area, as well as gaps in our knowledge, and directions for future studies.