L-Arginine is an amino acid that the body uses to make nitric oxide, a compound that relaxes blood vessels. Better blood flow can help nutrients and oxygen reach working muscles during exercise.
People take it before training to support circulation and reduce the time muscles need to recover. For best uptake, take L-Arginine on an empty stomach. Some blended forms are easier on the stomach.
L-Arginine can drop blood pressure and may interact with blood pressure drugs, nitrates, and blood thinners. Avoid it if you have an active herpes infection, low blood pressure, or kidney problems. High doses are not advised when kidney function is reduced.