You’ve known for some time that supplementing with arginine preworkout leads to increased vascularity, better muscle pumps, and more intense workouts. These effects are due to increased production of the potent vasodilator nitric oxide (NO). For the most part the effects of nitric oxide on muscle growth and strength have been credited to its ability to increased muscle blood flow, thus supporting delivery of anabolic (muscle building) nutrients and flushing of metabolic byproducts (such as lactic acid).

However, accumulating scientific evidence not only substantiates better muscular gains, but also shows that arginine does much more than promote vasodilation and muscle pump. In a recent study, scientists from the Shriners Hospital for Children in Galveston, Texas, investigated the anabolic potential of arginine, independent of nitric oxide related mechanisms. Using a burn model of injury in rabbits, the researchers found arginine significantly increased net protein balance and recovery in skin and skeletal muscle compared to animals that received an amino acid mixture of equal nitrogen content.

The researchers concluded that arginine produces true anabolic effects that specifically act by stimulating the transport of amino acids into injured tissues (i.e., those in a catabolic state), leading to increased amino acid availability for protein synthesis to promote anabolism.

As with most muscle building supplements, arginine evokes muscle growth through various but complementary mechanisms. The ever familiar nitric oxide related mechanism is just one. With continuous research being conducted on this popular amino acid, you can expect there’ll be more data to come on how it elicits anabolic effectiveness.