Creatine Monohydrate is a natural substance which has a key role in the processes which provide energy for the cells. The only direct source of energy, needed for the contraction of muscle cells, is the molecule adenosine triphosphate (ATP). The macroergic molecule of ATP can provide energy for a very short period of time, thus it transforms to adenosine diphosphate (ADP). For maintenance of necessary energy, it is required a constant recovery of ATP through a transformation from ADP to ATP. Creatine monohydrate has a fundamental role in this process because when the muscles are resting it is transformed into creatine phosphate through a process called phosphorylation. Creatine phosphate provides its phosphate group to ADP in order to transform it to ATP. There is a balance between the quantity of creatine and creatine phosphate in the organism as nearly 1/3 of the creatine in our bodies is free and 2/3 is in the form of creatine phosphate. The higher the level of creatine is in the body, the higher the creatine phosphate is. Thus it increases the speed of effective recovery of ATP, respectively increases the energy and work capacity of muscle cells. The result is more muscle power in short explosive contractions, which are part of the power training, which helps the increase of muscle mass. Creatine is nitrogen containing carboxylic acid. It is contained mainly in animal products (meat, fish) and the easiest way to supply with it is through supplementation. Creatine is a fundamental food supplement for muscle building programs.