The role of the breeders and owners is essential to the development of the Thoroughbreds and to their future performances. The benefits of exercise from an early age on horses of this very early breed have been demonstrated by scientific studies. Exercise and race training are said to positively affect the development of the young Thoroughbred's musculoskeletal system by promoting bone density and muscle mass. Thus, Thoroughbreds who start training at the age of two years have greater sporting longevity than individuals beginning at three or more.