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", even though the world record for the 200 m has had a faster average speed in the men's race since the mid 1990s.

In the past, athletes often competed over 100 yards (91 m) instead of the 100 m, especially in the United States. This shorter distance 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.

Record performances

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 twelve 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 9.69 s is held by Usain Bolt of Jamaica, set at the 2008 Beijing Olympic Games final on August 16, 2008. The current women's world record of 10.49 s was set by Florence Griffith-Joyner, in Indianapolis, Indiana, on 16 July 1988.

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. In 2003 revelations of failed drug tests by sprinting legend Carl Lewis before the 1988 Seoul Olympics also put the validity of his achievements into question.^[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 unsportsmanlike. 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 s 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 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 current rule, introduced in February 2003, 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. In order to avoid such abuse, the IAAF considered in 2005 to change the rule so that the first false starting athlete is immediately disqualified,^[2] but many countries objected as 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."^[3]

Climatic conditions

Climatic conditions are a crucial factor for good performances in the 100 m. Air resistance is the primary climatic factor in sprint performances. 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". The fastest recorded time for the distance, although excluded from the records because of wind assistance, was 9.68 s by Tyson Gay of the United States on 29 June 2008 during the 2008 U.S. Olympic Track & Field Trials at Hayward Field in Eugene, Oregon; the tail wind speed was 4.1 m/s, more than double the IAAF legal limit.^[4]

Furthermore, sprint athletes perform better at high altitudes because of the thinner air, which provides less air resistance. While there are no limitations on altitude, performances made at altitudes greater than 1000 m above sea level are marked with an "A".^[5]

Fastest 100 metres runners

Top thirteen all-time athletes ? men

Rank	Time	Wind (m/s)	Athlete	Date	Location
1	9.69	0.0	Usain Bolt	16 August 2008	Beijing
2	9.72	+0.2	Asafa Powell	2 September 2008	Lausanne
3	9.77	+1.6	Tyson Gay	28 June 2008	Eugene
4	9.79	+0.1	Maurice Greene	16 June 1999	Athens
5	9.84	+0.7	Donovan Bailey	27 July 1996	Atlanta
5	9.84	+0.2	Bruny Surin	22 August 1999	Seville
7	9.85	+1.2	Leroy Burrell	6 July 1994	Lausanne
		+0.6	Justin Gatlin	22 August 2004	Athens
		+1.7	Olusoji Fasuba	12 May 2006	Doha
10	9.86	+1.2	Carl Lewis	25 August 1991	Tokyo
		−0.4	Frankie Fredericks	3 July 1996	Lausanne
		+1.8	Ato Boldon	19 April 1998	Walnut
		+0.6	Francis Obikwelu	22 August 2004	Athens

Usain Bolt's 9.69 at Beijing on 16 August 2008 is also the Olympic record.
Justin Gatlin ran 9.77 in Doha on 12 May 2006, which was at the time ratified as a world record. However, the performance was annulled in 2007 after he failed a doping test in April 2006.
Ben Johnson ran 9.79 at Seoul on 24 September 1988, but he was disqualified after he tested positive for stanozolol after the race. He subsequently admitted to drug use between 1981 and 1988, and his time of 9.83 at Rome on 30 August 1987 was invalidated. Carl Lewis's 9.92 in the Seoul race was therefore recognized as the world record, and his two prior runs of 9.93 were seen as having equalled the previous world record.
Tim Montgomery's time (9.78 at Paris on 14 September 2002) was invalidated following his indictment in the BALCO scandal on drug use and drug trafficking charges. The time had stood as the world record until Asafa Powell first ran 9.77.
Ato Boldon has recorded 9.86 seconds on four occasions: the one detailed here is the first.

Top ten all-time athletes ? women

Rank	Time	Wind (m/s)	Athlete	Date	Location
1	10.49	0.0	Florence Griffith Joyner	16 July 1988	Indianapolis
2	10.65A	+1.1	Marion Jones	12 September 1998	Johannesburg
3	10.73	+2.0	Christine Arron	19 August 1998	Budapest
4	10.74	+1.3	Merlene Ottey	7 September 1996	Milan
5	10.76	+1.7	Evelyn Ashford	22 August 1984	Z�rich
6	10.77	+0.9	Irina Privalova	6 July 1994	Lausanne
6	10.77	+0.7	Ivet Lalova	19 June 2004	Plovdiv
8	10.78A	+1.0	Dawn Sowell	3 June 1989	Provo
	10.78	+1.8	Torri Edwards	28 June 2008	Eugene
	10.78	0.0	Shelly-Ann Fraser	17 August 2008	Beijing