When do racehorses reach their peak?

The age at which racehorses reach their peak, in terms of performance, depends on the age at which they start competition, the discipline in which they compete and other factors, including, but not limited to their genetic makeup, physical soundness and temperament. However, it is also true that young horses have lower blood volume and, hence, lower oxygen-carrying capacity, than their older, mature counterparts.

Generally speaking, thoroughbreds that race on the Flat typically reach their peak between 4 and 5 years. Of course, many of them do not race beyond 3 years, so never actually fulfil their potential. By contrast, National Hunt horses typically reach their peak between 7 and 10 years. It is important to note that, in the Northern Hemisphere, every thoroughbred has the same birthday – that is, January 1 – regardless of the month of the year in which is was actually born.