Bodybuilding & Gym Supplements

L-Arginine – The Key to Nitric Oxide (NO) Supplements

…But What Does it Do?

It seems you can’t go anywhere without hearing about Nitric Oxide products – from NO-Xplode, NaNO Vapor to NaNOx9, Nitric Oxide activators are all the rage. But because so many of these products contain caffeine, citrulline malate, beta-alanine and a host of other ingredients, it’s hard to determine what effect the Nitric Oxide activators, such as L-Arginine, actually have. Because of this, some people get the impression that they don’t do anything on their own. But what does science have to say about it? Let’s dive into the research.

The first study examined the effects of L-Arginine supplementation on circulation and exercise capacity, but the supplement was administered for only one week. The dosage for each participant varied, as the researchers administered .5g of L-Arginine per each 10kg of body weight. Even over the short duration of the study, significant differences were observed. The first result of the one-week L-Arginine supplementation was the decrease in pulmonary arterial pressure by 5mmHg. Additionally, the researchers found that pulmonary vascular resistance decreased by 16 percent. In some participants, this decrease was even more significant; 10 patients experienced a 20 percent drop in pulmonary vascular resistance. This allows for easier blood flow through the body, enabling oxygen and nutrients to be delivered to working cells more efficiently.

The changes in arterial pressure and vascular resistance were not the only significant changes that resulted from the L-Arginine supplementation. Mean systemic arterial pressure dropped by 5mmHg as well. Additionally, there was an 11 percent average decrease in systemic vascular resistance. The researchers found that exercise capacity was affected by the L-Arginine supplementation through the study as well. The participants experienced an increase of 65ml/min in VO2 max (maximal oxygen consumption, a measure of aerobic capacity). Because of this, there was also a significant increase in peak workload – an average of 10 Watts (1).

Other studies have also indicated that L-Arginine supplementation has worthwhile benefits for fitness enthusiasts. The amino acid has been shown to boost protein synthesis as well as help heal wounds. L-Arginine supplementation has also been linked to enhanced responsiveness of the pituitary gland, the master gland of the endocrine system.

Lastly, researchers have observed that the combination of L-Arginine and exercise have synergistic effects. One study involved participants in four groups – one placebo, one participating in exercise, one supplementing with L-Arginine, and one exercising and supplementing with L-Arginine. While both the exercise-only and supplement-only groups did experience improvements in vasodilation over the four-week period, the group that exercised and used L-Arginine had the greatest results, with arterial diameter increasing by 12 percent (3).

Based on this research, it seems there are many benefits to be attained by saying “Yes” to NO supplements.


1. Nagaya, Noritoshi, et al. Short-term Oral Administration of L-Arginine Improves Hemodynamics and Exercise Capacity in Patients with Precapillary Pulmonary Hypertension. American Journal of Respiratory and Critical Care Medicine, 2001; 163(4): 887-891.

2. Brown, Liz. Arginine and Exercise. Better Nutrition, 2000. 62(6): 30.

3. Hambrecht, R., et al. Correction of endothelial dysfunction in chronic heart failure: additional effects of exercise training and oral L-arginine supplementation. Journal of the American College of Cardiology, 2000; 35(3):706-713,


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