400 Metres

The 400 metres, or 400 metre dash, is a common sprinting event in track and field competitions. It has been featured in the athletics programme at the Summer Olympics since 1896 (1964 for women). On a standard outdoor running track, it is exactly one lap around the track. Runners start in staggered positions and race in separate lanes for the entire course. In many countries, athletes previously competed in the 440 yard dash (402.336 m)—also referred to as the 'quarter-mile'—instead of the 400 m (437.445 yards), though this distance is now obsolete. An athlete who competes in the 400 m may still be referred to as 'quarter-miler'.

Maximum sprint speed capability is a significant contributing factor to success in the event, but athletes also require substantial speed-endurance and the ability to cope well with high amounts of lactic acid to sustain a fast speed over a whole lap. Whilst considered to be predominantly an anaerobic event, there is some aerobic involvement and the degree of aerobic training required for 400 metre athletes is open to debate.

The United States men dominate this event. The current men's world record is held by American Michael Johnson, with a time of 43.18 seconds. The world indoor record holder is Kerron Clement, in 44.57 seconds. The current women's world record is held by Marita Koch, with a time of 47.60 seconds. Grenadan Kirani James is the reigning men's world and Olympic champion; Amantle Montsho is the reigning women's world champion, while Sanya Richards-Ross holds the women's Olympic title. The men's Paralympic world record of 45.07 seconds is held by Oscar Pistorius.

An Olympic double of 200 metres and 400 m was first achieved by Valerie Brisco-Hooks in 1984, and later by Michael Johnson from the United States and Marie-José Pérec of France both in 1996. Alberto Juantorena of Cuba at the 1976 Summer Olympics became the first and so far the only athlete to win both the 400 m and 800 m Olympic titles.