What is l-argine?

Answer 1

I think you mean L-Arginine or just Arginine. It's an amino acid. i.e. It's a protein. Bodybuilders like it. It is found in whey protein which is full of similar things like leucine, valine, glutamine, lysine, alanine, and glycine. It helps muscles grow, and when taken properly, it also causes the pituitary gland to release more growth hormone.