Exerkine

An exerkine is a signaling molecule released in response to exercise that helps mediate systemic adaptations to exercise.

Background
Exerkines come in many forms, including hormones, metabolites, proteins and nucleic acids; are synthesized and secreted from a broad variety of tissues and cell types; and exert their effects through endocrine, paracrine and/or autocrine pathways. These effects are thought to underly much of the health benefits of exercise in terms of enhanced resilience, healthspan and longevity.

The study of exerkines is the focus of the field of exercise endocrinology. Though the existence of exerkines had been speculated about as early as the 1960s, the identification of the first exerkine, IL-6, which is secreted from contracting muscles, didn't occur until 2000. In 2012 a new exerkine, irisin, was discovered and found to be involved in the regulation of energy expenditure, attracting significant scientific and public attention to the field. To date many thousands of potential exerkines have been identified, though only a limited number have been studied in any depth. Research is ongoing to understand how they function individually and in concert.

Etymology
The word 'exerkine' was coined in 2016 by Mark Tarnopolsky and colleagues, based on a combination of the beginning of 'exercise' and the beginning of κίνησις (kínēsis, Ancient Greek for 'movement').