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Old 05-29-2005, 02:06 PM
Darkhorse Darkhorse is offline
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Default Part 1

The Real Secret

Here’s where things get real interesting. You may want to be seated for this, because I’m about to blow the lid off the whole deal.

Arginine is the amino acid known to be the most potent insulin secretagogue, meaning that it causes insulin release from the pancreas (4). Now this is of critical importance, because insulin itself stimulates vasodilation and blood flow (2), and this occurs via elevations in nitric oxide synthesis (27).

So arginine stimulates insulin, and insulin stimulates nitric oxide. Nitric oxide causes vasodilation and increased blood flow. Hmmm… Combining this info with what the scientific literature tells us, we can see that much of arginine’s vasodilatory effect can be attributed to insulin secretion!

In fact, one study examined the extent of this very effect, and the results are shocking. Researchers infused the standard 30 grams of arginine with or without blocking insulin release from the pancreas (15). As usual, the massive arginine infusion increased blood flow. But, when insulin release was blocked, blood flow decreased by 77%!

When the latter experiment was repeated with an insulin infusion, blood flow was completely restored! So, over three-quarters of the increased blood flow response was caused by insulin. While not all arginine-induced blood flow can be attributed to insulin, you must remember that these studies use the equivalent of over 40 grams orally ingested arginine, which isn't even possible to tolerate.


The Revised Theory:

Arginine -> Insulin -> Nitric Oxide -> Vasodilation -> Nutrient Delivery -> Muscle Growth and Strength

You have to wonder if the companies who produce these supplements knew this when they began to market them. If they did, then they intentionally swindled people. If they didn’t, then they clearly didn’t have any idea what they were asking people to put into their bodies. Either way, it’s lose-lose for them.

To make things worse, AKG is being shown to play a role in stimulating insulin secretion (23), suggesting that companies may have indeed been trying to pull the wool over our eyes the whole time.

While this addition may seem beneficial, you have to remember that we still have no real evidence even suggesting that any of these products work at reasonable doses. And don't forget, an increase in insulin levels (and therefore blood flow) is all too easy to obtain without NO products.

Why would we use arginine to stimulate blood flow when we can get direct effects by manipulating insulin? In Part II of this article, I'll tell you how to do that without arginine supplements. The good news is, you're probably already doing it!

Summary

• Arginine blood flow stimulators ("nitric-oxide" or "NO2" supplements) have been shown to increase vasodilation, but only in unfed people receiving enormous doses through an IV.

• Oral arginine supplementation doesn't affect blood flow.

• A dose as low as 10 grams has been associated with gastric upset when consumed orally. This dose has no significant effect on glycogen storage, even if it didn't cause diarrhea.

• Time release arginine is supposed to lead to a "perpetual pump" effect. New studies have shown this not to be the case.

• NO2 was shown to have no effect compared to a placebo on body composition or muscle strength.

• It's not possible for us to consume high enough levels of arginine to effectively increase nitric oxide levels.

• Copycat NO2 products are no better than the original supplement. In fact, those that contain glycocyamine should be avoided because of potential health concerns.

• If you think these products work for you, then you'd better look into the placebo effect.

• Arginine might temporarily elevate growth hormone levels, but only if you're able to take unrealistic doses. There's little evidence to support that this short term increase in GH would do anything for your physique anyway.

• In one study, arginine aspartate was shown to increase prolactin by an average of 75%. Prolactin is associated with decreased Testosterone levels.

• Five grams of arginine consumed during resistance exercise was shown to decrease normal exercise-induced GH output.

• The positive benefits of oral arginine supplementation can only be achieved through doses higher than the human body can handle. And most (but not all) of this effect is mediated by insulin. So if you want to have blood flow increases equivalent to a huge IV arginine infusion, just manipulate insulin through other means (which will be discussed in the next article.)




About the Author

David J. Barr is a Doctoral student at the prestigious University of Texas Medical Branch amino acid metabolism lab, which is almost single handedly responsible for our pre and post-workout nutrition information. An accomplished varsity strength coach, he has certifications with the NSCA and USA Track and Field. In addition to his work for NASA at the Johnson Space Center, David’s research has involved everything from the cellular basis of muscle breakdown to work on critically ill catabolic patients. He can be contacted at DBMuscle@Hotmail.com.
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