Creatine supplementation.

Creatine monohydrate is a dietary supplement that increases muscle performance in short-duration, high-intensity resistance exercises, which rely on the phosphocreatine shuttle for adenosine triphosphate. The effective dosing for creatine supplementation includes loading with 0.3 g·kg·d for 5 to 7 days, followed by maintenance dosing at 0.03 g·kg·d most commonly for 4 to 6 wk. However loading doses are not necessary to increase the intramuscular stores of creatine. Creatine monohydrate is the most studied; other forms such as creatine ethyl ester have not shown added benefits. Creatine is a relatively safe supplement with few adverse effects reported. The most common adverse effect is transient water retention in the early stages of supplementation. When combined with other supplements or taken at higher than recommended doses for several months, there have been cases of liver and renal complications with creatine. Further studies are needed to evaluate the remote and potential future adverse effects from prolonged creatine supplementation.