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Can arginine lower exercise fatigue?

Despite being classified as a “nonessential” amino acid because it can be synthesized in the body, L-arginine is extremely popular with bodybuilders. In the past, arginine was touted as being the most potent amino acid for promoting growth hormone (GH)  release. This was based on studies showing that intravenous infusions of 30 grams of arginine did stimulate GH release. But you cannot provide that high a dose in an oral supplement form because nausea sets in when the dose of arginine reaches about 12 grams. Since then several studies have discounted the GH effect of oral arginine, while others have confirmed that it does work. The popularity of arginine had a resurgence with the introduction of nitric oxide (NO) stimulating supplements, most of which are based on arginine. NO is a important chemical in the body that plays a major role in blood vessel dilation, blood pressure regulation, hormone release, and numerous other processes in the body. While NO supplements are very popular, similarly to the arginine/GH effect, several articles have been published discounting this NO-boosting effect of arginine. These articles point out that the NO effect of arginine has occured mainly through infusions of 18 grams or more. Yet NO supplements rarely contain more than 4 grams of arginine per dose. Based on this, the critics of supplemental arginine suggest that any beneficial effect derived from oral arginine supplements can likely be attributed to the placebo effect.

But there is no denying the important role that arginine plays in the body. For example, arginine is involved in the synthesis of creatine in the body, and this alone can boost training efficiency. Several studies have confirmed that arginine does increase training efficiency, but again, these studies featured a intravenous administration of arginine at doses ranging from  3 to 30 grams. Some studies, however, used oral doses of up to 6 grams of arginine, and showed increased upper body strength, along with reistance to fatigue during training. In the most recent study, 50 untrained college men were divided into three groups: 1) placebo;2) 1.5 grams of arginine and 300 milligrams of grape seed extract; 3) 3 grams of arginine and 300 milligrams of grape seed extract (GSE). The study lasted a month, and subjects were tested at the start and end of the study with a electromyographic procedure that measure the highest output of muscle power before fatigue sets in.

Grape seed extract offers potent antioxidant effects, and also promotes the release of NO. As such it’s highly compatible with arginine. The results of the study showed that the group ingesting 1.5 grams of arginine showed a 22.4% increase in exercise-based fatigue resistance, while those ingesting the 3 gram dose of arginine showed a 18.8% increase in fatigue resistance. Those in the placebo group showed no changes.  As such, the smaller dose worked better, an effect not discussed by the study authors. They did offer an explanation for the beneficial effects of the arginine/GSE combo. The supplement was able to reduce metabolic exercise fatigue products, such as ammonia and lactate, and also likely boosted NO production. The increased NO boosted blood flow and oxygen delivery to working muscles, which would translate into decreased fatigue. One implication of this study is that the effects of ingesting oral arginine supplements are not all in the heads of those using these supplements. There may be a real effect marked by increased training efficiency.

Camic CL, et al. Effects of arginine-based supplements on the physical working capacity at the fatigue threshold. J Stengh Cond Res 2010: in press.

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