How the Hind Legs Support a Well Balanced Equine Athlete, a brief Synopsis:

A horse's back end is oftentimes referred to as the motor of the animal. It is not uncommon to hear horse people using the phrases, "driving from behind" or "stepping underneath himself" to depict an animal who is using their hind legs in a correct fashion. Put as simply as possible, when a horse is using their back end in the most efficient fashion, they are somewhat squatting, stepping underneath themselves with their hind legs. When such is the case, the animal's backside is lowered, necessitating their front end to raise up. When this happens, the result is an increase not only in motion (be it length or height of stride) but also an increase in the cadence of the gait.