12-hour run

A 12-hour run is a form of ultramarathon in which each competitor tries to run as far as possible in 12 hours. The event is typically held on 1 to 2 mi (1.6 to 3.2 km) loops, but sometimes is held on 400-metre (0.25 mi) tracks.^[1] Some races are held on trails and others are held on sidewalks in city parks. Top runners will often run 60 miles (97 km) or more (the best doing about 100 miles (160 km)), depending on conditions. Some participants will have a crew to help them, while others set up a camp with their equipment and supplies near the starting area, with good access from each loop.