Acute l-arginine supplementation increases muscle blood volume but not strength performance

Abstract

l-Arginine (L-arg) is an amino acid precursor to nitric oxide (NO). Dietary supplements containing L-arg have been marketed with the purpose of increasing vasodilation, thereby elevating blood flow to the exercising muscle and enhancing the metabolic response to exercise. Our goal was to identify the acute effect of L-arg supplementation on biceps strength performance, indicators of NO production (nitrite and nitrate - NOx), and muscle blood volume (Mbv) and oxygenation (Mox) during recovery from 3 sets of resistance exercise. Fifteen males participated in a randomized, double-blind, placebo-controlled study. After withdrawing resting blood samples, the subjects were supplemented with 6 g of L-arg (ARG) or placebo (PLA). Monitoring of Mbv and Mox with near-infrared spectroscopy began 30 min after supplementation and lasted for 60 min. The exercise protocol (3 sets of 10 maximal voluntary contractions of isokinetic concentric elbow extension at 60°·s(-1), 2-min rest between sets) was initiated 80 min after supplementation. Blood samples were drawn at 30, 60, 90, and 120 min after supplementation. Repeated measures ANOVA showed that Mbv significantly (p ≤ 0.05) increased in ARG compared with the PLA during the recovery period of each set of resistance exercise. NOx, Mox, peak torque, total work, and set total work were not significantly different between groups. We found that acute L-arg supplementation increases Mbv during recovery from sets of resistance exercise with no increase in strength performance. It is still premature to recommend nutritional supplements containing L-arg as an ergogenic aid to increase muscle strength during resistance training in healthy subjects.

A Brief Review of Critical Processes in Exercise-Induced Muscular Hypertrophy

“…An interesting observation was that growth hormone concentrations were enhanced by arginine supplementation [65] but, similar to other studies [68, 69], the transiently increased growth hormone concentration did not enhance MPS. Other attempts to enhance blood flow after resistance exercise by means of arginine or other nitric oxide-enhancing compounds have proved unsuccessful, at least in healthy young men [66, 67]. …”

The effects of pre- and post-exercise consumption of multi-ingredient performance supplements on cardiovascular health and body fat in trained men after six weeks of resistance training: a stratified, randomized, double-blind study

“…We recorded no change in resting NOx within or between groups during the intervention, which agrees with most previously published research [13] in healthy individuals. Interestingly, L-arginine has recently been shown to increase blood volume within the muscle (measured with near-infrared spectroscopy) without changing NOx [31]. It is possible that our participants experienced similar changes in blood volume without the detection of any change in NOx.…”

Oral adenosine-5’-triphosphate (ATP) administration increases blood flow following exercise in animals and humans

“…However, the daily dose needed to increase blood flow is high (6-24 g) and the ergogenic response may depend on the training status and health of the subjects [21]. Whereas some studies involving untrained or moderately healthy subjects showed that nitric oxide donors could improve tolerance to aerobic and anaerobic exercise, no significant improvements were measured in healthy [22] or highly-trained subjects [21,23]. In contrast, oral ATP increases blood flow at mg doses and has been shown to increase lean body mass, strength and power in highly trained individuals [6].…”