"Creatine is synthesized in the liver from the amino acids arginine and glycine. It is stored in the major skeletal muscles as well as the heart. Inside the muscle, creatine is converted (phosphorylated) to creatine phosphate (CP). CP is utilized by the body to maintain higher levels of ATP (energy molecules) during exercise. Consequently, CP enhances physical performance and reduces exercise fatigue by absorbing hydrogen ions released into muscles by lactic acid. Intense exercise, such as weight lifting and sprinting, depletes ATP and greatly increases the demand for creatine. "