FILE - In this Sunday, Aug. 28, 2011 file photo, Jamaica's Usain Bolt, third from bottom, false starts from the men's 100-meter final at the World Athletics Championships in Daegu, South Korea. Bolt was disqualified. Under the zero-tolerance false-start rule in place for the London Olympics, a sprinter's mistimed jump from the blocks could destroy four years of hard work in an instant. (AP Photo/Kin Cheung)