Nitric Oxide is a free form gas that is produced in the body and is used by the body to communicate with other cells in the body. To produce this gas, enzymes in the body break down the amino acid Arginine.
Nitric Oxide is a molecule consisting of one atom of nitrogen and one atom of oxygen. The production of Nitric Oxide occurs when the amino acid L-arginine is converted into L-citruline through an enzyme group known as Nitric Oxide Synthase (NOS)
"Summary research papers continue to flood the scientific journals and insights into the biological activity and potential clinical uses of nitric oxide (NO): a gas controlling a seemingly limitless range of functions in the body. Each revelation adds to nitric oxide's already lengthy resume in controlling the circulation of the blood, regulating activities of the brain, lungs, liver, kidneys, stomach and other organs." - Royal Society and Association of British Science Writers (1996)
NO increases vascular flow/blood flow in certain areas of the body to promote muscle growth, speed recovery times, and during workouts reduce muscle fatigue.
@Qwertty - The reason NO may make you "hyper" is from fast absorption and distribution of nutrients and other supplements due to the increased vascular flow and volume.
"A pint of sweat, saves a gallon of blood." - General George Patton