It's fairly well known that if you want to get ripped, you gotta pump some iron. But what's more of a surprise is that lab-engineered muscle also responds to a workout. Researchers at the Wake Forest Baptist Medical Center Institute for Regenerative Medicine have been looking at a way to help the body grow new muscle, and found that cells derived from muscle tissue (on a bio-compatible material) responded to "exercise." The research also showed that when tissue was applied to mice with reduced back muscles, those which received the exercised flesh enjoyed significant recovery benefits over those that just received the "sedentary" cells. The scientists who conducted the study suggest that if this was done on an equivalent human scale, muscle would have recovered to 70 percent of the force of native tissue within two months -- what they consider a significant amount. So if you ever need a transplant, perhaps that Thighmaster in the loft will finally come to use.