Irisin, Light My Fire

Abstract
Regular physical activity confers enormous fitness benefits. Exercise training enhances muscular endurance and strength, expends calories, and combats the development of common diseases such as obesity and type 2 diabetes. The effects of exercise are systemic and seemingly cannot be explained solely by the expenditure of calories in muscle ( 1 ). A recent study by Böstrom et al. ( 2 ) describes a mechanism that may elucidate how total body energy expenditure is increased by exercising muscle.