Creatine is a natural energy source that is used in muscle and nerve tissue and is stored as creatine phosphate phosphocreatine in muscle cells this phosphocreatine is the important factor that forms atp adenosinetriphosphate one of the bodies quick energy molecules creatine replaces the atp that has been used up during muscle contraction to allow prolonged intense activity creatine monohydrate supplementation increases phosphocreatine levels in the muscle especially when accompanied