The Nitrox Pump is made up of several ingredients that have been selected as they have been associated with increased production of nitric oxide in the muscles. Nitric oxide synthases (NOS) are enzymes that convert Arginine and citrulline to nitric oxide. Nitric oxide is a key biological messenger, playing a role in a variety of biological processes. It is known as a vasodilator which enhances blood flow in the body which could in theory increase the delivery of oxygen and nutrients to exercising muscle. This is associated with enhanced muscle pumps during exercise. A low level of nitric oxide is associated with physical fatigue.