400 metres hurdles

The 400 metres hurdles is a track and field hurdling event. The event has been on the Olympic athletics programme since 1900 for men and since 1984 for women.

On a standard outdoor track, 400 metres is the length of the inside lane, once around the stadium. Runners stay in their lanes the entire way after starting out of the blocks and must clear ten hurdles that are evenly spaced around the track. The hurdles are positioned and weighted so that they fall forward if bumped into with sufficient force, to prevent injury to the runners. Although there is no longer any penalty for knocking hurdles over, runners prefer to clear them cleanly, as touching them during the race slows runners down.

The current men's and women's world record holders are Karsten Warholm with 45.94 seconds and Sydney McLaughlin-Levrone with 50.37 seconds. Compared to the 400 metres run, the hurdles race takes the men about three seconds longer and the women four seconds longer. Men clear hurdles that are 91.4 centimetres (36 in) high, while women negotiate 76.2 centimetres (30 in) barriers.

The 400 m hurdles was held for both sexes at the inaugural IAAF World Championships in Athletics. The first championship for women came at the 1980 World Championships in Athletics – being held as a one-off due to the lack of a race at the 1980 Summer Olympics.

The first awards in a men's 400 m hurdles race were given in 1860 when a race was held in Oxford, England, over a course of 440 yards (402.336 m). While running the course, participants had to clear twelve wooden hurdles, over 100 centimetres tall, that had been spaced in even intervals.

To reduce the risk of injury, somewhat more lightweight constructions were introduced in 1895 that runners could push over. However, until 1935 runners were disqualified if they pushed over more than three hurdles in a race and records were only officially accepted if the runner in question had cleared all hurdles clean and left them all standing.

The 400 m hurdles became an Olympic event at the 1900 Summer Olympics in Paris, France. At the same time, the race was standardized; thus, virtually identical races could be held and the finish times compared to one other. As a result, the official distance was fixed to 400 metres, or one lap of the stadium, and the number of hurdles was reduced to ten. The official height of the hurdles was set to 91.4 centimetres (36 in). The hurdles are now placed on the course with a run-up to the first hurdle of 45 metres, distance between the hurdles of 35 metres each, and home stretch from the last hurdle to finish line of 40 metres.

The first documented 400 m hurdles race for women took place in 1971. In 1974, the International Amateur Athletics Federation (IAAF), now known as World Athletics, introduced the event officially as a discipline, with hurdles at the lower height of 76.2 centimetres (30 in). The women's race was not run at the Olympics until the 1984 Summer Games in Los Angeles where it was first staged with the first Men's World Champion having been crowned the year before at the inaugural World Athletics Championships. A special edition of the Women's 400m Hurdles took place in the 1980 IAAF World Championships in Athletics in response to the Women's 400m Hurdles not being included at the boycotted 1980 Summer Olympics in Moscow, and Liberty Bell Classic.