Backyard ultra

The runner who completes the second-most laps in a race is often referred to as the "assist", in the sense that their effort is ultimately what determines how long the race is allowed to continue--there is no predefined end length or time in a backyard ultra, as long as multiple runners can complete each loop within an hour.

Backyard ultras are the invention of Gary "Lazarus Lake" Cantrell,[3] who is also one of the founders and race directors of the Barkley Marathons.

[4] 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.

[3] Exactly one hour after a backyard ultra's first starting time, the competitors run 4.167 miles (6.706 km) with a one-hour window to finish.

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.

[10] The second-longest distance is 108 laps (450 miles (720 km)) achieved by American runner Harvey Lewis during the 2023 Big's Backyard Ultra in Bell Buckle, Tennessee, USA.

[11] The third-longest distance recorded is 107 laps, achieved by Ukrainian-Canadian runner Ihor Verys, also in the 2023 Big's Backyard Ultra.

Later that year in October 2019, Maggie Guterl would win Big's Backyard Ultra covering more than 402 km in 60 loops.