Characteristics -- Thoroughbred
Horse racers have commonly used thoroughbreds in longer races, ranging between 3/4 of a mile and two miles. Originally bred in Europe, the thoroughbred has bloodlines that reach back to the Arabian stallion. This genetic makeup contributes to the thoroughbred's faster speed, which tops out at about 40 miles per hour. The race horse Secretariat set the Kentucky Derby speed record in 1973 when clocked at 38 miles per hour over a distance of 1-1/2 miles.
Characteristics -- Quarter Horse
The American Quarter horse, bred in early colonial days during the latter half of the 18th century, reaches a top speed of about 55 miles per hour, according to ScienceDaily.com. In fact, the quarter horse was bred for this very purpose -- to go faster than the thoroughbred, and over a shorter distance. As the name suggests, the quarter horse runs a quarter-mile race, and the faster horses finish in about 20 seconds.
The inspiration behind breeding quarter horses for faster speeds came from an American thirst to see faster and more-exciting horse races. The English-style races, which lasted for up to two miles, were just too slow for an American audience. Before 1940, when the quarter horse got its current name, it was called a "quarter of a mile running horse." Because of the quarter horse's quick acceleration, race officials start timing quarter horses right out of the gate, while they start timing thoroughbreds after the horses are a few strides ahead of the gate.
Dr. Stanley Cohen, Ph.D., wrote in Psychology Today that quarter horses can only reach a speed of 47-1/2 miles per hour, in spite of higher speeds recorded by others. He also mentions the record-breaking thoroughbred speed reached by Secretariat at Churchill Downs, Kentucky. And both of these horses have a challenger -- the greyhound -- which can reach speeds up to 45 miles per hour. Cheetahs, however, exceed them all with their speeds ranging up to 70 miles per hour. A human being, on the other hand, maxes out at about 22 to 23 miles per hour.