Nick Coury just ran 173 miles in 24 hours at the Desert Solstice Track Invitational to set a new American record, beating out Mike Morton's 172.456 mile mark from 2012. That's 696 laps on a 400m track.
https://my.raceresult.com/188236/#0_3EF1B7
A quick breakdown of lap times puts the insane consistency of this performance into perspective - the consistency here is absolutely insane. Remember that these are elapsed times, so include bathroom stops, eating, etc. The only laps over 2:30 were bathroom stops and the only laps under 1:50 were his kick at the end after the record was clinched and he just went for broke.
Lap Time # Laps
> 2:30 5
2:20s 8
2:10s 17
2:08-2:10 15
2:06-2:08 115
2:04-2:06 169
2:02-2:04 178
2:00-2:02 125
1:50s 61
< 1:50 3