How Creatine Works in the Body

Creatine is a nitrogenous organic acid that aids in the supplementation of energy to cells in the body, especially to the muscles. While it can be naturally produced by the human body from amino acids, it is also available as a dietary supplement. Creatine is especially popular among bodybuilders and athletes because of its energy providing role and ability to help build muscle.

Creatine can be obtained from eating foods that are high in protein which are rich in amino acids. The amino acids L-arginine, glycine, and L-methionine are used by the body to make creatine. Creatine can also be obtained from a supplement in the form of a powder, capsule, or caplet. 

When synthesized naturally by the body, creatine is produced in the liver and kidney. From there, it goes through the blood and is taken up by tissues that need energy, such as working muscles.  Muscles use ATP (adenosine triphosphate) as their fuel. One component of ATP is three phosphate molecules that are strongly bound together. One phosphate is cleaved off to provide the muscle with energy fuel which results in ADP (adenosine diphosphate). Creatine works to add back a phosphate to the ADP to make ATP, resulting in a molecule that can be used for energy again. By increasing the number of creatine molecules, there is more fuel to repower ATP for the muscles.   

Muscle fibers are comprised of sarcomeres, which have actin and myosin that are contractile proteins. A signal from the nervous system is sent to contract the muscle, which the muscle then does by utilizing ATP. Because ATP powers the cycle of contractions, more creatine can result in more strength and muscle output.