In 1983, Kratochvílová broke the 800 m world record with a time of 1:53.28. At the World Championships shortly afterwards, she set a world record of 47.99 seconds to win the 400 m.[5]
Kratochvílová's 1983 400-metre world record of 47.99 seconds stood for two years until it was broken by her great rival Marita Koch in 1985. Koch's 400-metre world record of 47.60 seconds still stands in 2024. Kratochvílová's world record on an indoor track—49.59—stood until 19 February 2023 when the 400-meter indoor world record was broken by Femke Bol from the Netherlands with a time of 49.26.[6][7][8] Koch and Kratochvílová are the only women who have broken the 48-second barrier in a laned 400-metre outdoor race.[6] Her 800-metre world record is the longest-standing unshared track record in men or women's athletics, and it was described by 1996 Olympic champion Svetlana Masterkova as ".. very fast. It's impossible for women to run so fast. It will last for 100 years."[9]
Kratochvílová was a late developer, not breaking 53 seconds for
the 400 metres until she was 27, and she was 32 when she set her world
records.[10]
https://en.wikipedia.org/wiki/Jarmila_Kratochv%C3%ADlov%C3%A1
