100 metres

100 m (one hundred metres) is the shortest outdoor sprint race distance in athletics. The reigning 100 m Olympic champion is often named "the fastest man/woman in the world". A distance of 100 yards (91 m) was often run in the past, but this is now obsolete. Indoors events are normally held over 60 m (sometimes 50 m or 55 m) as few facilities have a 100 m indoor straight.

On an outdoor 400 m running track, the 100 m is run on the home straight, the start being set on an extension to make it a straight line race. Illegal drug use has been seen by some people as a means to gain a competitive edge; in particular, the scandal at the 1988 Summer Olympics when the winner Ben Johnson was stripped of his medal.

Major 100 m races, such as at the Olympic Games, attract much attention, particularly when the world record is thought to be within reach.

The men's world record has been improved upon eleven times since the introduction of electronic timing in 1968, never being surpassed by more than 0.05 s at a time. The current men's world record of 9.74 seconds is held by Asafa Powell of Jamaica, set in Rieti, Italy on September 9, 2007. The current women's world record of 10.49 seconds belongs to Florence Griffith-Joyner, set in Indianapolis on 16 July1988.

Due to the progression of record times compared to longer distances, the downward march of the 100-meter record has been criticized as more a measure of technological advances than athletic greatness. [1]

Start

At the start, some athletes play psychological games such as trying to be last to the starting blocks, although direct intimidation would be considered unsporting. The starter will keep the sprinters in the set position for an unpredictable time of around two seconds and then fire the starting gun.

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 0.1 seconds is considered a false start. The 0.1 second 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 it takes for a human to react to it.

For many years a sprinter was disqualified if they were responsible for two false starts individually. However, this rule was allowing some major races to be restarted so many times that the sprinters started to lose focus. The new rule is that, after one false start, anyone responsible for a subsequent false start is disqualified immediately. This rule has 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.