400m: the sport

400m is the longest sprint distance in Track Athletics. 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 the United States, athletes previously competed in the 440 yard dash (402.336 m) instead of the 400 metres, though this distance is now obsolete.
The 400m has achieved notoriety as a "man killer" because it is physiologically impossible to run at close to top speed for longer than 30 to 35 seconds before oxygen debt sets in and muscles "fill" with lactic acid. 400m runners must have good basic speed, they must be able to judge pace and they must learn to ignore pain!
For a technical analysis of the chief performance factors in sprinting see "Performance factors in sprinting".
 
The current men's world record is held by Michael Johnson of the USA, with a time of 43.18 seconds. The world indoor record holder is Kerron Clement (USA), in 44.57 seconds. The current women's world record is held by Marita Koch (of the then GDR), with a time of 47.60 seconds, set before the advent of out-of-competition testing. The reigning World Champions are Jeremy Wariner (USA) and Christine Ohuruogu (GBR). The reigning Olympic champions are LaShawn Merritt (USA) and Christine Ohuruogu (GBR), who’s since been banned for life from the Olympics  for failing to turn up to three doping tests. The Paralympic world record of 46.56 seconds is held by Oscar Pistorius of South Africa.
 
The performance improvements in this event, although partly explained by the introduction of synthetic tracks in the late sixties, are mostly due to the development of highly intensive training programmes which successfully build both speed and strength. Although 400m runners were traditionally divided into 200m/400m and 400m/800m types, it is the "pure" sprinters like Michael Johnson who now dominate the event.