A footrace of just under 5000 kilometres ran over 50 days.
Everyone running from 6 am until midnight. Getting up the next morning to run 95 kilometres. Repeating that day in and night out.
The track: One block in Queens, New York. A block just under 1 kilometre long.
This is not a sensible thing to do.
And for those 50 days the contestants know exactly what they will be doing:
One day clockwise, and the other anti-clockwise.