Obstacle Course Races, commonly known as OCRs, are individual or mass participation events where athletes run and overcome obstacles. They are typically held in parks, ski resorts, wilderness, rural, urban and suburban locations. Races can have up to 30,000 participants and are commonly in lengths of 100 m (sprint), 400 m, 3 km (short course), 5 km (international), 12-15 km (standard), 21 km (long course) to 50+ km (ultra).
Individuals and teams compete from 25 meters up to ultra distance in outdoor and indoor venues.
Obstacle Course Racing has its routes in military obstacle training, which has held a military obstacle run world championship annually since 1950.
The Tough Guy Competition in the United Kingdom (run annually since 1987) and survival Run that started in Holland around the same time were early versions of modern day OCR.
Sprint Adventure Races with man made obstacles were prolific in the United States from 1997 to 2010 and progressively eliminated the navigation, bikes, boats, and other equipment to make the events cheaper and more accessible. By 2010 Warrior Dash, Tough Mudder and Spartan Race became the dominant event brand in what is know known as OCR.