GNC AMP Creatine HCL 189™ is an advanced form of creatine that has been clinically studied with proven results. Creatine plays an important role in skeletal muscle protein synthesis and provides support for immediate energy production during exercise. The creatine found in GNC AMP Creatine HCL 189™ is an advanced, clinically studied form called polyethylene glycosylated creatine – or PEG Creatine HCL. This form has been proven to get into the muscle and improve strength and performance more efficiently than creatine monohydrate.