Creatine is found in the muscle in the form of free creatine and creatine phosphate with the amounts varying from person to person. Creatine phosphate performs a number of important roles in exercise metabolism, the best know being to provide a limited, but rapidly accessed, power system to regenerate ATP, the fuel currency of the muscle. This phosphagen’ power system is the most important fuel source for the performance of all-out sprints of 5-10 second duration. But creatine phosphate may also provide other roles in the generation of power via the anaerobic use of carbohydrate, and aerobic metabolism inside the muscle cell. It is not surprising that an increase in the muscle creatine phosphate level sounds attractive to an athlete.