<P> 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 . </P> <P> 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 . </P> <P> The best male athletes can run the 400 m hurdles in a time of around 47 seconds, while the best female athletes achieve a time of around 53 seconds . The current men's and women's world record holders are Kevin Young with 46.78 seconds and Yuliya Pechonkina with 52.34 seconds . Compared to the 400 metres run, the hurdles race takes the men about three seconds longer and the women four seconds longer . </P> <P> 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 . </P>

Who holds the world record for men's 400m hurdles