quality:corruption
Start

At the start, some athletes play psychological games such as trying to be last to the starting blocks.

At high level meets, the time between the gun and first kick against the starting block is measured electronically, via sensors built in the gun and the blocks. A reaction time less than 0.100 s is considered a false start. This time interval accounts for the sum of the time it takes for the sound of the starter's pistol to reach the runners' ears, and the time they take to react to it.

For many years a sprinter was disqualified if responsible for two false starts individually. However, this rule allowed some major races to be restarted so many times that the sprinters started to lose focus. The next iteration of the rule, introduced in February 2003, meant that one false start was allowed among the field, but anyone responsible for a subsequent false start was disqualified.

This rule led to some sprinters deliberately false-starting to gain a psychological advantage: an individual with a slower reaction time might false-start, forcing the faster starters to wait and be sure of hearing the gun for the subsequent start, thereby losing some of their advantage. To avoid such abuse and to improve spectator enjoyment, the IAAF implemented a further change in the 2010 season – a false starting athlete now receives immediate disqualification. This proposal was met with objections when first raised in 2005, on the grounds that it would not leave any room for innocent mistakes. Justin Gatlin commented, "Just a flinch or a leg cramp could cost you a year's worth of work." The rule had a dramatic impact at the 2011 World Championships, when current world record holder Usain Bolt was disqualified.