This is an exciting growing area of the sports supplements' industry. Also known as NO , NO2 , NOS , Nitro , Pump etc, these are derived from the amino acid L-Arginine.
This helps with the getting of the blood around the body but particularly the muscles and thus creating an instant "Pumped" effect in the gym, this means that heavy weights or higher repetitions can be achieved. The muscle gaining results are acheived pretty quickly and safely.