The backyard ultra is a form of ultramarathon race where competitors must consecutively run the distance of  in less than one hour, which is a pace of 100 miles per 24 hours. The race is over when only one runner remains to complete a lap. This runner is marked as the winner and only finisher, with all other runners receiving a "DNF" (Did Not Finish). There is no predetermined end length or time in a backyard ultra, and the race continues as long as multiple runners can complete the loop within an hour.

The Backyard Ultra has gained a reputation for its grueling and unpredictable nature, as well as the camaraderie among participants. Runners must endure sleep deprivation, exhaustion, and varying weather conditions, making it a true test of endurance and mental fortitude.

History 

Backyard ultras are the invention of Gary "Lazarus Lake" Cantrell, who is also one of the founders and race directors of the Barkley Marathons. 

The original backyard ultra is Big Dog's Backyard Ultra, which is held on Cantrell's property in Bell Buckle, Tennessee and is named after his dog. Today, Big's is an invitational race where the top competitors participate based on wins in a bracket of the various American and international backyard ultras.

Description
Exactly one hour after a backyard ultra's first starting time, the competitors run  with a one-hour window to finish. These laps are repeated hourly. The race is won when a single runner successfully completes a lap alone. If no competitor manages one more lap than the others, then all athletes receive a DNF and there is no winner.

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.

Some specific rules
 Each lap can be a round course, or an out-and-back course on the same path.
 In order to remain in the competition, the runners must be in the starting box when the hourly bell sounds. The starting box must be large enough to fit all the runners of the first lap; its size will not be changed during the competition.
 There will be a warning sound 3, 2 and 1 minutes before the bell.
 Except for relieving themselves, the runners are not allowed to leave the course. Personal assistance is forbidden on the course, but allowed between the laps. Aids like trekking poles are forbidden. Non-competitors may not be on the course. There may be aid stations on the lap if they support all competitors.
 Slower runners must allow faster runners to overtake them.

Difficulties in running a Backyard Ultra 
In contrast to usual ultramarathon races, untrained people can join a Backyard Ultra — and not drop out during the first handful of rounds, as the required pace is quite low: 14.4 minutes per mile, or 8.9 minutes per kilometer. Thus, the challenge is rather a mental one: No participant knows when the race will end, and the participant's ranking does not depend on themselves, but on whether their competitors are giving up.

As every runner has to start the next round at exactly the same time, a fast runner does not have an advantage over slower ones. While running too fast will burn the energy reserves, a slow speed will not allow enough rest before the next round. Thus, the main challenge lies in maintaining the running speed over dozens of hours, getting enough rest, and spending the resting time as efficiently as possible — with either a massage, a power nap, a restroom visit, or getting food and drinks. The most successful Backyard Ultra runners strive for a resting time of 14 to 18 minutes, forcing them to run 4.167 miles in 42 to 46 minutes.

According to Lazarus Lake, most runners do not drop out because of missing the per-round time limit, but because of their diminishing mental strength to carry on. This is well illustrated by Lake's statement that "[…] the hardest part of the course is between your chair and the starting corral". When a runner displays pain or fatigue, it often motivates the other runners to carry on because they expect him or her to give up.

Given the peculiarities of this running format, Backyard Ultra runners usually prepare by running private Backyard Ultras alone, with shorter distances per hour (for example, one, two or three miles every hour), and by optimizing the rest periods.

Records
The longest distance recorded by a competitor in a backyard ultra event is 102 laps () achieved by Australian runner Phil Gore during the 2023 Australian Backyard Masters held at Dead Cow Gully in QLD Australia. The previous world record was 101 laps () achieved by Belgian runners Merijn Geerts and Ivo Steyaert during the 2022 Backyard Ultra World Team Championships in October at their team’s home course in Belgium.  

The Female World Record for a backyard ultra performance is 74 laps () set by Jennifer Russo at the 2023 Capital Backyard Ultra in Lorton, VA. Prior to Russo’s record setting performance, the longest distance recorded by a female competitor in a backyard ultra event was 68 laps set by Courtney Dauwalter at Big's Backyard Ultra in October 2020 with an assist by Harvey Lewis. In May 2019, Katie Wright became the first woman to win a backyard ultra event running  in 30 hours during an event in New Zealand. She beat 5 other women and 40 men to emerge victoriously. Later that year in October 2019, Maggie Guterl would win Big's Backyard Ultra covering more than 402 km in 60 loops.

References

External links and literature 
 
 
 The official Backyard Ultra website

Ultramarathons
Endurance games
Long-distance running