Thoroughbreds are a breed of horse that is often used for racing. They horses were first bred during the early 1700s by mating Arabian with English horses. These horses have been specifically bred to be the fastest and strongest with the highest levels of endurance.
This breed of horse arose during the late 1600s to early 1700s. They were originally the offspring of Arabian horses, known for their speed and agility, and English horses, known for their strength. The result was a very fast horse that could carry significant weight and also travel long distances.
![](http://images.wisegeek.com/slideshow-mobile-small/jockey-on-brown-horse.jpg)
The most distinctive trait of all thoroughbreds is their lineage. All are descendants of three individual horses: the Byerley Turk, the Darley Arabian, and the Godolphin Arabian. These horses were given the last names of their owners were the three horses originally used to produce the thoroughbred line during the early 1700s. The family lines of each thoroughbred horse have been meticulously recorded for the past 300 years to ensure that they are part of the historical line.
![](http://images.wisegeek.com/slideshow-mobile-small/man-on-horse-jumping-over-obstacle.jpg)
Thoroughbred horse breeding aims to create the fastest and strongest horse available. Their strength is tested on the racetrack, and the best horses are bred to continue the thoroughbred line. Contemporary thoroughbred horses are significantly faster and taller than the thoroughbreds of the 18th century.
In 2012, the standard thoroughbred racehorse is 16 hands, or 64 inches (1.6 meters) tall). They usually weigh 1,000 pounds (453.6 kilograms) and are expected to run between 30 and 40 miles per hour (38 to 64 kilometers per hour). All horses, however, have different features and abilities, and the goal of all breeders is to create an animal that is faster and stronger than the average.
These horses differ from other breeds in their muscular structure. Quarter horses, a common breed of horse, are bred for strength and speed and have the muscular structure to produce these qualities. Arabian horses have musculature that promotes endurance, so while they can travel for great distances, they are not necessarily good candidates for carrying heavy loads. Thoroughbred horses possess muscles that give them both of these qualities and excel at both speed and endurance.