Physiological Basis for Creatine Supplementation in Skeletal Muscle and the Central Nervous System

Creatine (Cr; methylguanidino acetic acid) is one of the safest, most extensively studied, and popular supplements in the sports science community. Its primary role is to improve bioenergetics; by mediating phosphagen metabolism, Cr improves the availability of ATP for the myosin motor and improves force and power production. With resistance training, Cr-loaded muscle allows for a higher quality of training (e.g., more reps at a given weight, higher power output) that leads to a more rapid training performance gains and muscle fiber hypertrophy. Cr has, therefore, allowed an enhancement of muscle function and more rapid training gains within the genetic capabilities of the individual. Its role in endurance exercise is not well described but shows potential benefits for increased exercise economy at submaximal intensities. The important role of Cr in the nervous system has become a major topic of research, and its therapeutic benefits are becoming clearer. Finally Cr supplementation may have important implications for aging as well as for muscle wasting and insulin resistance.