Better Sex with Arginine
Did you hear the one about the ineffectual heart medication that was repackaged as a potency drug and became the most successful prescriptive launch in pharmaceutical history?
Repeatedly, medicines and supplements that faltered on their first go-round—such as Viagra —are discovered to be highly effective when used for different purposes.
That may be the case with the protein component arginine, which first came to light in the 1970s as a reputed human growth hormone releaser. Although the amino acid did bolster GH release in one study published in the Journal of Clinical Endocrinology, effective dosages were extremely high, and arginine eventually fell from grace in muscle-hungry GH circles. But don’t shut the door on your supplement cabinet just yet.
Arginine may have several surprising attributes for the athlete who is both a lover and a fighter. By relaxing arteries and increasing blood flow, arginine apparently speeds up muscle repair; it also seems to bolster gains in muscle mass, and new research shows it may even cause new contractile units to appear at the ends of muscle fibers. Toss in its usefulness as an erection enhancer, and you have a product that’s gone from washout to winner.
Most of arginine’s effects occur after enzymes transform it into nitric oxide or NO, a messenger gas that travels easily from cell to cell (and is different from nitrous oxide or N2O, which is the fun stuff your dentist gives you). According to recent work by scientists at Monash University in Melbourne, Australia, nitric oxide promotes blood flow to muscles, helping supply them with the oxygen and nutrients they need to function. The researchers compared increases in forearm blood flow caused by isotonic exercise before and after blocking nitric-oxide synthesis in 43 healthy men. The NO block caused a 19 percent reduction in blood flow to the working muscle and a 42 percent loss of blood flow to the muscle at rest.
Theoretically, better circulation due to extra nitric oxide from arginine could speed recovery from anaerobic exercise by helping eliminate accumulated lactic acid and acid ions from the muscle. It could also boost recovery and muscle synthesis by supplying the muscle with fresh glucose and amino acids to rebuild respective glycogen and protein stores.
Size Does Matter
The latest suggestion related to arginine is that nitric oxide tells your muscles to add extra contractile units (called sarcomeres) to the ends of their fibers in response to stretching, causing the muscles to grow bigger by growing longer. Supporting this theory is a study published in both the Journal of Physiology and the American Journal of Physiology, which suggests that holding the muscle of an adult animal in a stretched position causes both sarcomere addition and NO release. Additional support comes from UCLA researchers Timothy Koh, Ph.D., and Jim Tidball, Ph.D., who worked with rats whose leg muscles had atrophied due to immobilization in casts. After the casts were removed, one week of arginine supplementation led to faster relengthening of muscle than one week of control treatment.
Another animal study, published in Nutrition, found that arginine increases protein synthesis and lessens muscle breakdown in rats suffering from burns. Although it has yet to be shown whether arginine supplementation can enhance the anabolic effects of stretching and exercise in adult humans or the muscle-sparing effects in those who are recovering from injuries, this preliminary evidence is encouraging and will ideally stimulate further research. As for arginine’s other stimulating effects, dozens of studies reviewed in The Journal of Urology confirm that arginine allows more blood to enter the penis, most likely by relaxing smooth muscles within the organ that would otherwise constrain blood flow. This results in a firmer and longer-lasting erection. The process is similar to that of Viagra, so if you’re shy about asking your doctor for that famous former heart drug, arginine could be a face-saving (and far less costly) solution.