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
Athletics at the 2016 Summer Olympics – Men's 110 metres hurdles time comparison, and those athletes were allowed to run in a repechage round to improve their qualifying time. Two athletes Deuce Carter and Alexander John had been disqualified for failure to properly clear hurdles in those earlier races and were allowed to re-enter. Carter qualified for the semi-finals from the special race. Qualification rule: first 4 of each heat (Q) plus the 4 fastest times (q) qualified. Athletics at the 2016 Summer Olympics – Men's 110 metres hurdles The men's 110 metres hurdles event at the 2016 Summer Olympics took place between 15–16 August at the Olympic Stadium. The 2012