[pdwetz]

Probably most similar to ultra races, some of which are on a short repetitive loop over x time period (24 hour is "common"). Audience is probably closer to dozens of friends/family compared to packed stands of fans/gamblers, though!

[js2]

Also 48 hours and six days are recognized for world records by the IAU. http://www.iau-ultramarathon.org/

There's also this:

https://en.wikipedia.org/wiki/Self-Transcendence_3100_Mile_R...