The backyard ultra is a form of ultramarathon race where competitors must consecutively run the distance of 6706 meters (4.167 miles) in less than one hour. When each lap is completed, the remaining time within the hour is typically used to recover for the next hour's race.
Exactly one hour after a backyard ultra's first starting time, the competitors run an additional 6706 meters with a one-hour window for completion. These distance loops are repeated hourly. The race ends when the last runner or runners either concede or fail to finish the distance within the allotted time frame.
The distance the runners race each hour is set at miles or 6705.6 meters, which is then rounded up to 6706 meters. The total distance run by a competitor who completes 24 laps is exactly 100 miles. Backyard ultra races are usually held on a loop measuring 6706 meters, though in Sweden some have been held on a 400-meter track.
If no competitor manages one more lap than the others, then all athletes receive a DNF and there is no winner. In Sweden, the fastest to complete the previous lap is deemed the winner.
The longest distance recorded by a competitor in a backyard ultra event is 68 laps or 283.335 miles by Johan Steene at Big's Backyard Ultra in October 2018. The longest distance recorded by a female competitor in a backyard ultra event is 67 laps by Courtney Dauwalter at Big's Backyard Ultra in October 2018.
Guillaume Calmettes has completed the most 200+ mile finishes at 3, while Peter Cromie holds the record for most 100+ mile finishes at 7 (4 at 100, 2 at 150 and 1 at 200)
- "Sweden Runners - ÄBU 2017". swedenrunners.se. Retrieved 2017-07-11.
- "Big Backyard Ultra - October 15, 2016". ultrasignup.com. Retrieved 2017-07-11.
- "Ultrafestival - Team Ultrasweden LK - Friidrott - IdrottOnline Klubb". ultrasweden.se. Retrieved 2017-07-11.
- Pearson, Andy (October 31, 2018). "Big's Backyard Ultra Gets Bigger and Bigger". Trail Runner. Retrieved February 3, 2019.
- "BYU Lists". Google Docs. Retrieved 2019-04-27.