Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

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Arginine useless for bodybuilders, says study

More NO as a result of an L-arginine supplement? Better blood supply to the muscles? Enhanced muscle protein production? Forget it, say sports scientists at McMaster University According to their study, bodybuilders and other strength athletes have nothing to gain from taking supplements that contain L-arginine. We read the article, but are not about to bin our NO boosters.

The researchers got 8 men in their early twenties to train one leg on resistance machines. Afterwards the men drank a shake containing amino acids plus 10 g arginine [ARG], or a shake containing the same amount of glycine [CON]. Like arginine, glycine is a non-essential amino acid, but without the ergogenic effects of arginine.

The researchers analyzed the blood of their subjects after training to assess the effects of the supplements. As they expected, the subjects' amino acid concentration rose, but the concentration of nitrite and nitrate did not rise. If arginine supplements were to boost NO, you'd expect to find more nitrate and nitrite in the blood. The subjects' growth hormone levels did rise.

Arginine useless for bodybuilders, says study

The researchers observed no change in the blood supply to the trained leg muscles. So arginine supplements didn't cause the blood vessels to widen.

Arginine useless for bodybuilders, says study

After the training session the researchers took samples from the non-trained [REST] and the trained [EX] leg muscles and examined the muscle protein synthesis. This had risen in the EX samples and not in the REST samples, but the arginine supplementation had no effect.

"These results bring into question the ergogenic potential of arginine in healthy young men and suggest that neither NO synthesis nor muscle blood flow are limiting to muscle anabolism when an adequate amount of EAA is provided", the researchers conclude.

The study is interesting, but it hasn't undermined our belief in NO boosters. Not only because the researchers didnít give their subjects the supplements until after they had trained instead of beforehand, but also because, in our experience, you only start to notice the effects of NO supplements after a few days of taking them. And more to the point, you wouldn't expect NO supplements to lead directly to more muscle protein production, but rather to muscle tissue recruiting more stem cells.

J Nutr. 2011 Feb;141(2):195-200.

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