Standardbred harness racing horses are so called because in the early years of the Trotting Registry, the standardbred stud book established in the United States in 1879 by the National Association of Trotting Horse Breeders, only horses who could race a mile in a standard time or better, or whose get (offspring) could race a mile in standard time or better, were entered in the book.
Standardbreds are known for their skill in harness racing, being the fastest trotting horse in the world. In continental Europe all harness races are conducted between trotters. A trotter's forelegs move in unison with the opposite hind legs -- when the right foreleg moves forward so does the left hind leg, and vice versa. In Australia, Canada, New Zealand, the United Kingdom, and the United States, races are also held for pacers. Pacers' forelegs move in unison with the hind legs on the same side. Wikipedia, the free encyclopedia.