400 meter race is a common track running event. It is the longest common sprint distance. 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 meter, though this distance is now obsolete.

The current men's world record is held by 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 (set before the advent of out-of-competition testing).
The reigning Olympic champions are LaShawn Merritt and Christine Ohuruogu.
The Paralympic world record of 46.56 seconds is held by Oscar Pistorius.

The 400 meter dash is an endurance sprint incorporating the speed of the sprinter and the endurance of the half miler. It is considered by many to be one of the most demanding and grueling of competitive events. Usually the 400 meter runner will fall into two distinct categories‑‑sprinter types and half‑miler types. Both of these types have had their share of success over the years. Occasionally you will find an athlete who possesses some characteristics of both the sprinter and half miler.