Exercise and interleukin-6

Strenuous exercise induces increased levels in a number of pro- and anti-in flammatory cytokines, natural occurring cytokine inhibitors, and chemokines . Thus, increased plasma levels of tumor necrosis factor (TNF)-alpha, inter leukin (IL)-1 beta, IL-1 receptor antagonist (IL-1 ra), TNF-receptors (TNF- R), IL-10, IL-8, and macrophage inflammatory protein (MIP)-1 are found afte r strenuous exercise. The concentration of IL-8 increases as much as 100-fo ld after a marathon race. It has recently been demonstrated that IL-6 is pr oduced locally in contracting skeletal muscles and that the net release fro m the muscle can account for the exercise-induced increase in arterial conc entration. Larger amounts of IL-6 are produced in response to exercise than any other cytokine, IL-6 is produced locally in the skeletal muscle in res ponse to exercise, and IL-6 is known to induce hepatic glucose output and t o induce lipolysis. These facts indicate that IL-6 may represent an importa nt link between contracting skeletal muscles and exercise-related metabolic changes. (C) 2001 Lippincott Williams & Wilkins, Inc.