There is strong scientific evidence to support controlled exercise at a young age in thoroughbreds. It has been shown that exercise has a positive effect on the musculoskeletal system because it encourages adaption with a resultant increase in strength and density of bones. An adult level of tissue maturity has been shown to have been attained in racehorses before their two year old racing career usually commences.

The evidence shows that horses that raced as two-year olds had significantly more race starts during their careers from three-years old upwards than those who did not race until they were  three-years old or older.

(1)  BEVA press release – New evidence suggests early exercise in Thoroughbreds may help musculoskeletal health

New Zealand Policy – Racing of two year old horses