How it works
Competitors run once around a 400m track. They start from blocks set in staggered positions and run in lanes.
A reaction time – measured by sensors in the starting pistol and on the blocks – of less than 0.1 is deemed a false start and runners are recalled. After one false start, anyone responsible for a subsequent false start is disqualified immediately. A runner can also be disqualified if he or she steps out of their designated lane.
History
One of the original events at the Ancient Olympics was the 'diaulos', a race around two marks on a course roughly equivalent to the current 400m.
The 400m for men has been in every Olympic Games since 1896. Women first contested the distance at the 1964 Tokyo Games.
Did you know
Scotsman Eric Liddell, the 1924 Olympic champion, was born in Tianjin, China. His parents were missionaries.
Gold standard
American men have won the past six Olympic golds. US women, however, last provided the Olympic champion in 1984. The Caribbean nations, led by Jamaica and the Bahamas, are very strong, while Russian women also have an impressive heritage.
Icons
Michael Johnson
The first man to win the Olympic 400m twice (and the only man to win the 400m and 200m), Johnson is the greatest one-lap runner. The Texan took gold in the Atlanta (1996) and Sydney (2000) Games. He also won four world titles, and in 1999 set a world record - 43.18 - that still stands today.
Marie-Jose Perec
France’s Perec was the first runner of either gender to win Olympic gold twice, crushing the opposition at the 1992 Barcelona and 1996 Atlanta Games (where, like Johnson, she performed a double by snatching 200m glory, too). Long-legged and graceful, she also won two world titles.