footfall pattern. One distinction is whether the footfall rhythm is isochronous, four equal beats in a 1-2-3-4 rhythm; or a non-isochronous 1-2, 3-4 rhythm created by a slight pause between the groundstrike of the forefoot of one side to the rear of the other. Many breeds of horses inherit the ability to perform these gaits, which may be observable naturally from birth or may present with a minimal amount of training. Some horses without apparent inborn gaited ability can be taught to "gait" or amble. However, training usually is not successful unless there is some inherited genetic ability in the horse. Ambling gaits can be taught by slightly restraining the horse at a trot or pace. The length of the stride is kept long, but the rider asks the horse to alter its balance to break up the two strides in such a manner to produce a four-beat gait. Sometimes, this effect is accidentally produced in an attempt to create the slow two-beat jog trot desired in western pleasure competition when the horse cannot sustain a slow jog and falls into a shuffling, four beat gait described as "trotting in front and walking behind," which is penalized in the show ring. Some horses can both trot and amble, and some horses pace in addition to the amble instead of trotting. However, pacing in gaited horses is often, though not always, discouraged. Some horses neither trot nor pace easily, but prefer their ambling gait for their standard intermediate speed. Conformation also plays a role. Horses with a longer back at the lumbosacral joint or "coupling" will find it easier to perform a lateral ambling gait, though they may also have to work harder to have proper collection. An average length back still allows a horse to perform ambling gaits, though a very short-coupled horse usually can only perform the trot. A well-laid back shoulder and somewhat horizontal hip angle favor a longer length of stride and is helpful in horses that fox trot, while a steeper shoulder angle combined with more sloping croup produce a stride more desirable in some lateral gaits such as the running walk. A particular form of ambling gait considered desirable in one breed is often penalized in another. For example, the Missouri Foxtrotter is specifically bred to perform the fox trot, a diagonal ambling gait, while the Paso Fino is bred to perform lateral gaits and