Karsten Warholm, of Norway, second left, clears the final hurdle to beat Rai Benjamin, of United States to win a semifinal of the men's 400-meter hurdles at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Charlie Riedel)

Dalilah Muhammad, of United States, reacts after winning a heat in the women's 400-meter hurdles at the 2020 Summer Olympics, Saturday, July 31, 2021, in Tokyo. (AP Photo/Petr David Josek)

Karsten Warholm, of Norway, wins a men's 400-meter hurdles semifinal at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo. (AP Photo/Petr David Josek)

Sydney Mclaughlin, of United States, wins a heat in the women's 400-meter hurdles at the 2020 Summer Olympics, Saturday, July 31, 2021, in Tokyo. (AP Photo/Petr David Josek)

Dalilah Muhammad, of United States, reacts after winning a heat in the women's 400-meter hurdles at the 2020 Summer Olympics, Saturday, July 31, 2021, in Tokyo. (AP Photo/Petr David Josek)

Sydney Mclaughlin, of United States, wins a heat in the women's 400-meter hurdles at the 2020 Summer Olympics, Saturday, July 31, 2021, in Tokyo. (AP Photo/Martin Meissner)

FILE - In this June 21, 1980, file photo, Edwin Moses, gold medal winner in 1976 in Montreal, wins in the 400 intermediate hurdles as the 1980 Olympic trials in Eugene, Ore. Moses, the man who once won a remarkable 107 finals in a row from 1977-87 and who lowered the world record to 47.02 seconds during his prime, says he has been enjoying watching hurdlers break new barriers over the past two years. (AP Photo/File)

Karsten Warholm, of Norway, wins a men's 400-meter hurdles semifinal at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo. (AP Photo/Petr David Josek)