Acute supplementation of L-arginine affects neither strength performance nor nitric oxide production.
BACKGROUND
L-arginine is a semi-essential amino acid involved in nitric oxide production. As nitric oxide is an important vasodilator, L-arginine supplementation would increase blood perfusion and, subsequently, muscle performance during exercises. The aim of this study was to determine the acute effect of L-arginine supplementation on strength performance and nitric oxide levels in healthy trained individuals.


METHODS
In a double-blind, placebo-controlled, cross-over study, 12 men were randomly assigned to L-arginine or placebo supplementation. Subjects received 6 g of L-arginine or placebo 60 minutes before strength test (maximum number of repetitions, 3 sets at 70% of one repetition maximum on bench press and at 80% of one repetition maximum on knee extensions, 2 minutes of rest between sets and exercises). Blood samples were collected before supplementation and 6 min after exercise.


RESULTS
Plasma nitrite levels did not significantly change after L-arginine or placebo supplementation and strength-training exercise (placebo, from 13.01±1.18 to 11.83±2.81 mM; L-arginine, from 10.95±4.09 to 11.99±2.5 mM). There was a significant reduction in the number of repetitions performed from set 1 to set 3 in each set of both bench press and knee extension, but no significant interactions were observed between placebo and L-arginine.


CONCLUSIONS
These results do not support the use of L-arginine as an ergogenic aid for strength performance, at least in context of acute use immediately before resistance exercise performance.
School of Physical Education of Army, Rio de Janeiro, Brazil - claudiameirelles@yahoo.com.br.
Claudia M
CM
Meirelles
Department of Pharmacology and Psychobiology, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
Cristiane
C
Matsuura
D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism*; D054874:Athletic Performance; D018592:Cross-Over Studies; D019587:Dietary Supplements / Q000032:analysis*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000097:blood; D055070:Resistance Training; D055815:Young Adult
D009573:Nitrites; D009569:Nitric Oxide; D001120:Arginine