Nitric oxide (NO) is a powerful vasodilator. It is produced by cells lining blood vessels and arginine is used by the enzyme nitric oxide synthase (NOS) to make NO. The idea is that arginine supplementation is able to increase NO production and increase blood delivery and thus amino acids and other nutrients to muscle cells during and after exercise. These nutrients could in turn strengthen the processes that build muscle in response to resistance exercise. In addition to the positive benefits of arginine in this manner, researchers have also indicated that citrulline might also be beneficial, as it can be used to make arginine. One reason is that a lot of the arginine that is consumed is metabolized by the intestinal bacteria and arginase in the small intestine wall and liver, and never makes it to the blood vessels of muscle. On the other hand, citrulline is not metabolized in such a manner. And, on a related note, polyphenolic compounds in grapes and extracts might serve to optimize NOS activity.
Arginine is used to make nitric oxide, which can dilate blood vessels leading to muscle tissue.
Was this article helpful?