Fat Ox

Fat Ox is an Aravaipa Running ultra in Goodyear, Arizona, held in November at Estrella Mountain Regional Park. The event features fixed-time racing, with 48-hour, 24-hour, 12-hour, and 6-hour options, alongside set-distance races at 100 miles, 100K, and 50K. In the timed races, runners continue on the course for their event's duration, making the challenge about managing pace, breaks, food, and patience rather than reaching a distant finish. The course is a USATF-certified loop of approximately 0.988178 miles, allowing crews and families frequent views of runners. Fat Ox originated from Nathan Coury’s college thesis on fat oxidation and ultra running, accounting for the name and the event's scientific humor. Aravaipa calls it a family fixed-time festival, and the format accommodates various participants: elite 24-hour runners, ultrarunning novices trying a shorter timed race, and distance runners aiming for 50K, 100K, or 100 miles on a controlled loop.