This is a fascinating ultra marathon run. You do not know how long it is until you drop out our win. The Big Dog Backyard Ultra does 4 1/24 mile loops each hour. You can run four miles in an hour? Great! Now do it again. And Again. And … that is the point.
You can follow one of these links to get more information. Or read about in on Wikipedia.
You may haven noted the distance – it is set to run 100 miles each day. They run a lot. The record to date is “75 laps or 502.95 km or 312.525 miles by Karel Sabbe at the international part of Big’s Backyard Ultra in October 2020.” Over three days of running.
Perhaps you will enjoy this video of it.