How does Creatine work?

In a brief overview, creatine works to help generate energy. When ATP loses a phosphate molecule and becomes adenosine diphosphate (ADP), it must be converted back to ATP to produce energy. Creatine is stored in the human body as creatinephosphate (CP) also called phosphocreatine. When ATP is depleted, it can be recharged by CP. That is, CP donates a phosphate molecule to the ADP, making it ATP again.

An increased pool of CP means faster and greater recharging of ATP, which means more work can be performed. This is why creatine has been so successful for athletes. For short-duration explosive sports, such as sprinting, weight lifting and other anaerobic endeavors, ATP is the energy system used. To date, research has shown that ingesting creatine can increase the total body pool of CP which leads to greater generation of energy for anaerobic forms of exercise, such as weight training and sprinting. Other effects of creatine may be increases in protein synthesis and increased cell hydration. 

Creatine has had spotty results in affecting performance in endurance sports such as swimming, rowing and long distance running, with some studies showing no positive effects on performance in endurance athletes. Whether or not the failure of creatine to improve performance in endurance athletes was due to the nature of the sport or the design of the studies is still being debated.

Creatine can be found in the form of creatine monohydrate, creatine citrate, creatine phosphate, creatine-magnesium chelate and even liquid versions.