Katie Ledecky crushed the world record last night in the women’s 400 metre freestyle, swimming 3:56.46, to better her own world record by 1.91 seconds. Since swimming world records converted to all LCM marks in the late 1950s, that is the 7th largest improvement in the women’s 400 free world mark – see the table below. Further, in an era in which records are often improved by 100ths of a second, the mark is a quantum leap, as it has been 40 years since anyone improved the 400 free world record by a larger margin, done in 1976 by Barbara Krause at the GDR Olympic Trials, most likely with a little, shall we say, assistance. The all-time best in this category is held by Debbie Meyer, the woman whose marks Ledecky is chasing in Rio, who won the 200-400-800 freestyle treble at the 1968 Mexico City Olympics, and improved the WR by 3.8 seconds at the 1967 Pan American Games. Second is another swim legend to whom Ledecky can aspire, Shane Gould, who won gold at the 1972 Olympics by bettering the world mark by 3.16 seconds. But that was all in a different era.
|4:32.6||3.8||Debbie Meyer||USA||27 July 1967||Pan American Games|
|4:19.04||3.16||Shane Gould||AUS||30 August 1972||Olympic Games|
|4:11.69||3.07||Barbara Krause||GDR||3 June 1976||GDR Olympic Trials|
|4:42.0||2.5||Marilyn Ramenofsky||USA||11 July 1964|
|4:26.7||2.3||Debbie Meyer||USA||1 August 1968||AAU Championships|
|4:39.5||2.2||Marilyn Ramenofsky||USA||31 August 1964|
|3:56.46||1.91||Katie Ledecky||USA||7 August 2016||Olympic Games|