Protein and amino acid metabolismEffects of L-arginine supplementation on exercise metabolismMcConell, Glenn KAuthor Information Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia Correspondence to Dr Glenn McConell, Department of Physiology, The University of Melbourne, Parkville, Victoria, 3010, Australia Tel: +61 3 8344 5844; fax: +61 3 8344 5818; e-mail: [email protected] Current Opinion in Clinical Nutrition and Metabolic Care: January 2007 - Volume 10 - Issue 1 - p 46-51 doi: 10.1097/MCO.0b013e32801162fa Buy Metrics Abstract Purpose of review To describe the influence of acute and chronic administration of L-arginine on metabolism at rest and during exercise. Recent findings There has been substantial examination of the effect of infusion and ingestion of L-arginine at rest. It has been clearly demonstrated that L-arginine administration improves endothelial function in various disease states. In addition, L-arginine infusion at rest increases plasma insulin, growth hormone, glucagon, catecholamines and prolactin. Such hormonal changes affect metabolism. There has, however, been very little examination of the effect of increases in L-arginine availability during exercise. This is important to study as there is preliminary evidence that L-arginine infusion, probably via increases in nitric oxide (NO), alters skeletal-muscle metabolism during exercise. There is a need for further research, especially to understand the mechanisms of how L-arginine affects exercise metabolism and also to determine whether the hormonal responses that occur in response to L-arginine at rest are also present to some extent during exercise. Summary This line of research may have important therapeutic implications as there are indications that L-arginine augments the effects of exercise training on insulin sensitivity and capillary growth in muscles. © 2007 Lippincott Williams & Wilkins, Inc.