Creatine works mainly through its effects on energy metabolism. Adenosine triphosphate (ATP) is a molecule that carries energy within cells and is the main fuel source for high-intensity exercise. When cells use ATP for energy, this molecule is converted into adenosine diphosphate (ADP) and adenosine monophosphate (AMP). Creatine exists in cells in the form of creatine phosphate (or phosphocreatine), which donates a high-energy phosphate group to ADP, thus turning this molecule back into ATP.
By increasing the overall pool of cellular phosphocreatine, supplementation with creatine can accelerate the recycling of ADP into ATP, thereby quickly replenishing cellular energy stores. This increased availability of energy can promote improvements in strength and power output.[1] The pro-energetic properties of creatine don’t just affect skeletal muscle, but nearly all body systems, including the central nervous system (which comprises the brain and spinal cord).[2]