Endurance riding is a horse racing sport of the equestrian discipline, where riders and horses compete in races over very long distances. Competitors are allowed to compete with horses of any breed, but most riders compete with the Arabian breed, as its well known for its natural endurance. Endurance races are conducted over various distances, typically between 50 to 100 miles. The most commonly used distance is, the single day 50 mile race. Single day races of distances of 75 and 100 miles, and a 2-day 100-mile race where a rider completes 50 miles each day for two consecutive days, are some of the other race formats. Races over distances longer than 100 miles are very rarely used in competitions. There are two variants of endurance riding, endurance races and competitive trail races. Endurance races are conducted on a regular plain course, whereas trail race courses have various terrains and natural obstacles. In all the races, the health of the horses are also taken into the account to decide the winner. After a rider completes the race, the horse is examined by a vet to check if the horse is "fit to continue". The rider to first cross the finish line with their horse in a healthy condition is declared as the winner.