Sgt. Jerrod Fields, a U.S. Army World Class Athlete Program Paralympic sprinter hopeful, works out at the U.S. Olympic Training Center in Chula Vista, Calif. A below-the-knee amputee, Fields won a gold medal in the 100 meters with a time of 12.15 seconds at the Endeavor Games in Edmond, Okla., on June 13, 2009. Sgt. Fields lost his leg to an improvised explosive device in Baghdad, Iraq, in March 2005. You can read more about him here. (Photo courtesy army.mil.)