Nitric oxide plays a major role, it simply increases the blood flow and supply oxygen to the muscle tissues.  Nitric oxide also facilitates the communication between the cells.  When one performs the workout actually he is damaging his muscle to build it. The increase blood flow and deliver y of oxygen to the muscle tissue helps in rapid healing. Force Factor being a natural product also has added features that increase the stamina and boost up the mental strength. Arginine increase the production of human growth hormone and it also boosts the immune system. I know this would have been useful.