Myostatin and Mass Exodus
Myostatin is a hot topic in bodybuilding these days. Although discovered by scientists at Johns Hopkins Medical School in 1997, myostatin remained obscure, except among researchers, until recently. It’s a naturally occurring body protein, and its synthesis is coded by genes. It also limits muscular growth. Scientists are still uncertain as to exactly how that works, but they believe it may block the activity of immature muscle cells, called satellite cells, that are involved in muscle repair and growth.
Animals born without the genes that code for myostatin become strikingly muscular and devoid of any superficial bodyfat—precisely the appearance sought by most competitive bodybuilders. Animals without myostatin also have muscles that are two to three times larger than the average. Test animals that were bred specifically to lack the myostatin gene showed significant muscular growth and a lack of bodyfat—and no particular health problems.
The implication is that myostatin-blocking activity is a magic bullet for a muscular body. Thus far, the only abnormalities that have turned up in myostatin-knockout animals are comparative weaknesses in the vertebral bone structure, evidently due to the excessive muscle surrounding the vertebral column—an imbalance between great muscular bulk and bone density in that area of the body. All other bony structures appear normal in such animals.
Scientists were quick to recognize the medical potential of arresting myostatin activity in such diseases as muscular dystrophy, cancer and AIDS, which are characterized by pronounced muscular wasting, or catabolism, and elevated levels of cortisol and myostatin. Several substances are known to block myostatin activity in the body. Recently, scientists isolated GASP-1, a protein that appears to be the body’s natural myostatin blocker. Some food-supplement companies are now selling products that contain a type of sea algae that, when exposed to myostatin in the lab, binds to it and ostensibly blocks its activity. Because what happens in a test tube isn’t necessarily duplicated in the human body, however, the true test will be to give the supposed myostatin blocker to human athletes, give a similar group a placebo, and then observe the results. No such study has been published.
One overlooked way to inhibit myostatin is simply by lifting weights, according to a newly published study that followed four men and four women, age 20 to 30, and another three men and four women, age 65 to 70, for nine weeks.1 The subjects, all untrained, participated in a resistance-exercise program consisting of just one exercise: one-leg extensions done three times a week. At the end of the study all subjects showed an average 37 percent drop in myostatin activity, an effect solely due to exercise.
Keep in mind that the research sample consisted of untrained adults who did only one exercise three times a week: The effect would likely be greatly magnified in healthy, hard-training bodybuilders. In fact, my guess is that myostatin activity would decrease by at least twice as much. Conversely, not working out for an extended time would induce a gradual rise in myostatin activity.
1 Roth, S.M., et al. (2003). Myostatin gene expression is reduced in humans with heavy-resistance strength training: A brief communication. Exp Biol Med. 228:706-709.