Monday, December 6, 2010

Myostatin: perhaps not so great after all by Jerry Brainum

Myostatin is a protein that was discovered in 1997 by researchers at Johns Hopkins University Medical School. The primary function of myostatin is to prevent muscle growth. In doing so, it works with other catabolic pathways in the body, including those involving the release of cortisol, the primary catabolic hormone. Animals deficient in myostatin show extreme muscle mass, along with decreased bodyfat. Naturally, such an outcome is very attractive to bodybuilders. This led to the premature release of a supplement derived from seaweed that was marketed as a "myostatin blocker." This particular property of the seaweed was produced in one in vitro study. This means that the substance blocked myostatin, but in a test-tube. There was no evidence that it duplicated this effect in an intact human body.
      The fact that there was no real evidence that the reputed myostain blocking supplement actually worked didn't deter greedy companies from touting the supplement. I had a feeling at the time that the supplement was useless, and wrote this in a bodybuilding magazine. Not long afterward, studies done with human subjects confirmed that the touted myostain blocking supplement did not work as advertised. Since that time, other alleged myostain-blocking supplements have appeared on the market. One is based on follistatin, another naturally occuring protein that does appear to block the effects of myostatin in the body. But follistatin, being a protein, is degraded in the gut before it can become active if consumed orally. The studies showing that follistatin blocked myostatin involved follistatin being injected into mice and rats. The producers of the follistatin supplement have yet to produce a human study showing that it works, although they have published anecdotal reports of efficacy, as well as an in house study, which is useless.
      While the properties of myostatin may appear to hold tremendous potential for those seeking added muscle mass, there are lesser known effects of blocking myostatin that may take the wind out of the sails of those dreaming about massive muscles with myostatin blocking. For one, there is evidence that while blocking myostatin will indeed increase muscle mass, it doesn't offer any boost in muscle strength. The latest study to report this effect compared mice bred to completely lack myostatin and normal mice. While the myostatin-deficient mice (or null mice) showed larger muscle size, they did not show any increased strength. Even worse, examination of muscle fibers of the myostatin null mice showed increased degeneration. Other studies show that myostatin plays a role in tendon regeneration, and blocking myostatin can result in an increased rate of tendon injuries. So my advice is to avoid all reputed myostatin blocking supplements, especially since none of them work. There are experiemental drugs that do effectively block myostatin, but taking such drugs now could be hazardous to health, since all the biological nuances of myostatin have yet to be established.

Gentry, B, et al. Hindlimb skeletal muscle function in myostatin-deficient mice. Muscle and Nerve 2010: in press.

©,2015 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited

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