Innovation in prosthetics technology is enabling a whole new population of athletes to emerge—a population that includes quite a few older folks. John Grimm of Vail, Arizona, at 70 years old, is one of them. And with the aid of his new RUSH™ Foot, developed by Ability Dynamics, Tempe, Arizona, he says that he is a higher-performing athlete today than with his previous prosthetic foot, a carbon-composite foot with a flexible keel. Grimm knows something about pushing himself physically, having spent 30 years as a United States Navy SEAL from 1960 to 1990. Training to qualify as a U.S. Navy SEAL is infamously tough, requiring more than a year of specialized underwater, combat, and survival training.