Energizer are preparations which supply the necessary energy for showing other physically demanding performances. They excite for activity, and at the same time they increase concentration and keep attention. Creatinine is a side product of creatine metabolism. Creatine decomposes in muscles for the purpose of producing energy. Sportsmen, athletes and bodybuilders should use the products with creatine which is quite stabile in body liquids and does not decompose into creatinine (that is responsible for convulsions, digestive disorders, muscular pain, etc. and it must be removed by kidneys). L-carnitine is a substance peculiar to the body, which is essential in fat degradation. It transfers fatty acids into mitochondrias, where they are transformed into energy.