ultramarathon

An ultramarathon is any running race longer than the marathon distance of 42.195 kilometers (26.219 miles). Common ultramarathon distances include 50 km, 100 km, and 100 miles (about 161 km); there are also timed events such as 6-hour, 12-hour, and 24-hour races, and multi-day stage races. Ultramarathons can be held on roads, on trails, or on mixed terrain, with trail formats comprising the majority of popular events.

The modern ultrarunning movement grew in the late 20th century with the establishment of iconic races such as the Western States Endurance Run and the Ultra-Trail du Mont-Blanc, and with increasing international participation. Race formats vary in elevation, terrain, and climate, from high-altitude mountain routes to fast, flat courses.

Races are typically self-supported or partly supported by aid stations, and most have cutoffs that determine finish eligibility. Competitors usually rely on crew support, drop bags, and scheduled nutrition and hydration. Mandatory gear requirements may apply in certain conditions, such as cold, rain, or remote terrain.

Training for ultrarunners emphasizes high weekly mileage, long back-to-back runs, and progressive volume while balancing recovery. Nutrition and electrolyte management are central, with athletes practicing real-world fueling during long training runs. Common challenges include injury, sleep loss, heat or altitude stress, and mental fatigue.

The sport is overseen internationally by the International Association of Ultrarunners (IAU), which coordinates world championships and records, while many races are organized independently. Participation has grown to include a broad range of ages and genders, with increasing attention to safety, environmental impact, and race ethics.