creatine (Cr)

creatine (Cr)

nitrogenous organic compound, held primarily in skeletal muscle. Obtained from a normal diet (mainly in meat and eggs) and also synthesized from amino acids in the liver. In resting conditions, about 60% is in the phosphorylated form, creatine phosphate (CrP). Cr+CrP constitute the creatine pool. Creatine is the fastest selling ergogenic aid among athletes; creatine supplementation aims to increase the CrP energy reserve, delaying creatine phosphate (CrP) depletion and hence reducing requirement for anaerobic glycolysis; also facilitating CrP resynthesis between bouts of high-intensity exercise, enhancing performance during multiple repeats. When supplementation is combined with resistance training, leads to greater gain in muscle mass. A typical protocol involves daily Cr intake of 20-25 g for 5 days, then continued daily supplementation with 2-3 g. The response varies between individuals, with uptake inversely related to the initial muscle concentration, and 30% appearing to be 'non-responders'. See also ergogenic aids; appendix 4.4 .