Wounded warriors participating in the 2013 Marine Corps trials observe their coach demonstrate how to take off from a starting block during a practice session aboard Camp Pendleton, Calif., Feb. 28, 2013. The trials offer wounded active duty, retired and allied service members the opportunity to compete in swimming, cycling, track and field, strength and conditioning, shooting, archery, sitting volleyball, and wheelchair basketball. The top 50 competitors in each sport go on to compete against the other branches of the military at the Warrior Games in Colorado Springs, Colo., in May. (Official US Marine Corps photo by Sgt. Michael V. Walters/Released)