Ultramarathon

An ultramarathon, also called ultra distance or ultra running, is any footrace longer than the traditional marathon length of 42.195 kilometres (26 mi 385 yd). Various distances, surfaces, and formats are raced competitively, from the shortest common ultramarathon of 31 miles (50 km) and up to 3100 miles. World Championships are held by the International Association of Ultrarunners (IAU) for 50 km, 100 km, 24 hours, and ultra trail running. The Global Organization of Multi-Day Ultramarathoners (GOMU) holds World Championships for 48 hours and 6 days. World Records are ratified and recognized by World Athletics (50 km and 100 km), the IAU (50 km up to 6 days), and by GOMU (48 hours up to 5000 km).

Around 100 miles (160 km) is typically the longest course distance raced in under 24 hours, but there are also longer multiday races commonly held as 48 hours, 200 miles (320 km), or more, sometimes raced in stages with breaks for sleep.

The oldest and largest ultramarathons are on road, including the Comrades Marathon (over 10,000 finishers annually) and Two Oceans Marathon (over 6,000 finishers annually). The world's longest certified Footrace is the Self-Transcendence 3100 Mile Race. Many ultras have historical significance, including the Spartathlon, based on the 246 km run of Greek messenger Pheidippides from Athens to Sparta during the Battle of Marathon in a day and a half to seek aid against the Persians.

There is also overlap with the sports of trail running and mountain running. Some 100 miles (160 km) races are among the oldest and most prestigious events, especially in North America. The oldest and also the largest trail race is the SainteLyon 78km in France (over 5,000 finishers annually).