When do horses reach peak performance?
The performance of a racehorse depends, in no small part, on the capacity of its blood to deliver oxygen to, and remove carbon dioxide from, its tissues. Consequently, it stands to reason that a mature racehorse, which has higher blood volume and, hence, higher oxygen-carrying capacity is capable of running faster than an immature horse. However, respiration is not the whole story; the age at which a horse reaches peak performance is also influenced by its pedigree, soundness, temperament and training regime, among many other factors.
Healthy horses have a natural lifespan of 25 years or more, on average, and do not stop growing until they are around five years old. However, Flat-bred horses typically begin their racing career as two-year-olds and those with breeding potential are often retired to stud at the end of their three-year-old campaigns. Thus, while they would typically reach peak performance between four and five years, if kept in training, they never have the chance to do so.
By contrast, many National Hunt-bred horses are robust, strong, late-maturing types, a.k.a. ‘store’ horses. Almost invariably, male horses are gelded, or castrated, and have no breeding value, so are allowed to mature before being put into training at the age of three, four or more. Such horse typically reach peak performance between seven and ten years, depending on the age they enter training and the discipline(s) in which they compete.