Genetic doping can permanently increase the muscle mass in mice and there are delivery methods which could avoid the need for immune system suppression

The origins of genetic doping have nothing to do with sports. Rather, researchers have been trying to develop ways to repair muscles in people with muscular disorders. Here’s how it works: A synthetic gene is engineered to secrete a specific protein, one that’s normally involved in muscle growth and repair. That gene is delivered by an otherwise harmless virus, and when it reaches the cell it’s designed to work with, it "turns on." With access to more of the protein than would normally be produced, the damaged muscle is enhanced. Current techniques allow this all to happen without actually altering a person’s genetic makeup.

But according to Dr. H. Lee Sweeney, a professor of physiology at the University of Pennsylvania Medical School who’s worked to develop such treatments, healthy athletes could benefit greatly from similar methods. "The same things, if introduced into normal muscle, would make them much more responsive to exercise and training, and much more responsive to repairing themselves following an injury," says Sweeney. For that reason, Sweeney doesn’t believe sports leagues and governing bodies will allow it.

The change in muscle performance for an elite athlete could be substantial. The actual effect would depend on a number of factors (including the intensity of training), but in tests, lab rats who were injected and then made to do resistance exercises increased their muscle mass by 15 percent on top of what they would have normally achieved with exercise alone. More important to an athlete, the effects could last for years, if not decades. Researchers tested it on monkeys some 15 years ago and still haven’t seen the induced changes drop off.

Dr. Charles Yesalis, a professor emeritus at Penn State who’s researched performance-enhancing drugs, says he expects this "cascade" method of doping — in which athletes trick their bodies into releasing more of something that would increase performance — will become increasingly common as new advances are made. And while he says there are different ways athletes could use such a method, "The No. 1 thing that comes to mind is genetic doping."

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