We've heard of men changing genders and then competing in women's events, and even of women switching teams to compete. Michael Jordan changed sports, and boxer Roy Jones Jr. juggles weight divisions so often you never know where he'll end up. But there's only one athlete we know of who went from being an excellent, able-bodied outdoorsman to a one-armed top jock over the course of a couple of bloody hours. A four-limbed climber of some renown around his home of Aspen, Aron Ralston famously hacked off his own wing with a pocket knife after finding himself trapped under a rock during a solo climb. These days, the tri-limbed Ralston is concentrating on adventure racing. It's unknown if team members permit him to carry his own blade.