Written by justis berg
30 June 2011

Arginine Has No Effect On Vasodilatation In Healthy, Young Adults

Arginine is necessary for the execution of many physiological processes. These physiological processes include hormone secretion, an increase in growth hormone output, the removal of toxic waste products from the body, and immune system defenses. L-Arginine is a precursor to nitric oxide (NO) because L-Arginine and L-Citrulline are converted to NO synthases. Despite limited scientific data, L-arginine is also being marketed as an ergogenic aid, aimed at augmenting NO production and increasing blood flow in healthy individuals. L-Arginine and supplements containing L-Arginine are advertised as being capable of increasing blood flow during resistance exercise for greater delivery of oxygen and nutrients during exercise, and causing a transient increase in muscle pumps.

Researchers from the University of Illinois examined the effects of L-Arginine on vasodilatation in healthy young adults, to determine if taking L-Arginine before resistance exercise could enhance nitric oxide and increase muscle pumps. The researchers designed the study so that the subjects performed the same resistance exercise protocol, but on one occasion they used a placebo and the on other, they took 7 grams of L-Arginine orally. The resistance exercise bout consisted of 4 sets of 5 repetitions using 80 percent of the 1-RM bench press. After the bench press, 4 sets of 10 repetitions using 70 percent of the 1-RM biceps curl were completed for the biceps curl, using a two-arm curl bar. A 2-minute rest was given between all sets.

 

Immediately following the study, researchers examined several markers for vasodilatation or muscle blood flow. 7 grams of L-Arginine before resistance exercise did not have any effect on vasodilatation responses to resistance exercise in healthy young subjects. As expected, acute resistance exercise increased both the resting blood flow and the blood flow response to resistance exercise. Resting flow and peak exercise blood flow increased to a similar extent after both conditions in the study. The scientists commented that L-Arginine may not the limiting factor in the nitric oxide pathway for vasodilatation. Other physiological factors such as acetylcholine and catecholamines, which are elevated during exercise, also increase NO release and NO dependent dilation, respectively. Therefore, further augmenting NO production during exercise via L-Arginine supplementation may not be possible. The present research suggests that taking L-Arginine alone before exercise has little effect on vasodilatation and its impact on nitric oxide.

 

Ø     Fahs CA, Heffernan KS, Fernhall B. Hemodynamic and Vascular Response to Resistance Exercise with l-Arginine. Med Sci Sports Exerc, 2009 Mar 7.