400 metres hurdles 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 cm (3 feet) for men and 76.20 cm (2 ft, 6 inches) for women. The hurdles were now placed on the course with a run-up to the first hurdle of 45 metres, a distance between the hurdles of 35 metres each, and a home stretch from the last hurdle to the finish line of 40 metres. The first documented 400 m hurdles race for women took place in 1971. The International Association
400 metres hurdles allow a forward body lean. Unlike the 110m hurdles, a significant forward body lean is not that necessary due to the hurdles being lower. However, the trail leg must be kept bent and short to provide a quick lever action allowing a fast hurdle clearance. The knee should pull through under the armpit and should not be flat across the top of the hurdle. It is also important that the hurdler doesn't reach out on the last stride before the hurdle as this will result in a longer bound being made to clear the hurdle. This will also result in