Start of the men's 100 metres final at the
The 100 metres, or 100-metre dash, is a
On an outdoor
The 100 m (109.361 yards) emerged from the metrication of the
US athletes have won the men's Olympic 100 metres title more times than any other country, 16 out of the 28 times that it has been run. US women have also dominated the event winning 9 out of 21 times.
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 0.1 s is considered a
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
Runners normally reach their top speed just past the halfway point of the race and they progressively decelerate in the later stages of the race. Maintaining that top speed for as long as possible is a primary focus of training for the 100 m.
The winner, by IAAF Competition Rules, is determined by the first athlete with his or her
Climatic conditions, in particular air resistance, can affect performances in the 100 m. A strong head wind is very detrimental to performance, while a tail wind can improve performances significantly. For this reason, a maximum tail wind of 2.0 m/s is allowed for a 100 m performance to be considered eligible for records, or "wind legal".
Furthermore, sprint athletes perform a better run at high altitudes because of the thinner air, which provides less air resistance. In theory, the thinner air would also make breathing slightly more difficult (due to the