Its 43.18 seconds held by Michael Johnson
Michael Johnson world record: 43.18.
World Record 400m Individual Medley Michael Phelps (USA) August 9, 2008 Time: 4:03.84
It's somewhere around 44 to 48 seconds
Marita Koch of the GDR holds the record at 47.60s.
dont have a clue
46.70 by Kevin Young USA
2:54.20 by USA in 1998