SportLife Nutrition® Arginine is a 100% pure L-arginine powder made with the latest technology. L-arginine is an amino acid found in many nutrients. L-arginine is an effective amino acid that is essential for the production of nitric oxide (NO) in the human body. Nitric oxide, in turn, causes the dilation of small blood vessels, thereby improving blood flow to the muscles, among other things. As a result, there is increased access to oxygen and nutrients in the muscles, which significantly enhances the muscles' ability to recover quickly from training and develop more rapidly.