How Many Ways Can a Horse Move? Footfall Patterns With Names

A gait is a repeating pattern of footfalls, identified by which feet strike the ground in what order, how many are down at any moment and whether there is a moment with none down at all. Speed is a consequence rather than a definition, since a horse can move quickly or slowly within a gait and changes gait rather than simply accelerating, and the transitions happen at fairly consistent speeds because each pattern is efficient over a particular range. The distinction matters for riders because each gait feels completely different to sit, for veterinarians because lameness shows up as a disturbance in the pattern, and for biologists because the same patterns appear in other four-legged animals with the same physical logic behind them.

Four gaits are standard and the differences are in timing rather than effort:

• •The walk, a four-beat pattern with at least two feet always on the ground and no airborne phase
• •The trot, a two-beat pattern with diagonal pairs moving together, separated by a brief suspension
• •The canter, a three-beat pattern that is asymmetrical and leads with one side
• •The gallop, a four-beat pattern with a suspension while the legs are gathered beneath the body
• •The pace, a two-beat pattern with lateral rather than diagonal pairs, natural in some breeds
• •Various ambling gaits, four-beat and smooth to sit, which some breeds perform and others cannot

Whether a galloping horse ever has all four feet off the ground was argued about for centuries and could not be settled by eye, because the motion is too fast. Painters had long depicted the gallop with the legs extended fore and aft in a flying pose, which is how the eye interprets what it cannot resolve. The question was answered in 1878 when Eadweard Muybridge arranged a row of cameras triggered in sequence as a horse ran past, producing images showing unambiguously that all four feet do leave the ground, and that the moment occurs when the legs are gathered under the body rather than extended. The result changed how horses were painted and, more importantly, demonstrated a method of analysing motion that led directly toward moving pictures.

Some breeds perform additional gaits that most horses cannot, and the reason turns out to be genetic. These ambling patterns are four-beat and lack the suspension that makes a trot bouncy, so a rider sits still while the horse moves at speed, which is why they were prized for long journeys before roads and vehicles were good. Breeds across Iceland, the Americas, Spain and elsewhere have them, which suggested a shared ancestry, and a mutation in a single gene affecting the spinal circuitry that coordinates limb movement was identified in 2012 as the basis. Tracing that variant through ancient DNA indicates it spread from medieval England and was carried outward by horse trade, which connects a piece of molecular genetics to a documented history of breeding and transport.

The reason animals switch between discrete patterns rather than varying continuously is energetic. Measuring oxygen consumption across speeds shows that each gait has a range where it costs least per distance travelled, with a clear minimum, and that the transitions occur close to where the curves cross, so an animal allowed to choose its own speed on a treadmill switches at the energetically sensible point. Forcing an animal to use the wrong gait for its speed measurably increases the cost. A second factor is peak force on the limbs, which rises steeply at the top of a gait's range and appears to trigger the switch before the energetic optimum in some cases. The same logic applies to other animals including humans, whose walk-to-run transition occurs at a predictable speed for the same reasons.

A gait is defined by which feet land in what order and whether any moment has none down, with speed following rather than defining it. Walk, trot, canter and gallop differ in timing, and some breeds perform additional smooth four-beat patterns. Photography in 1878 settled that a gallop does leave the ground, with the legs gathered rather than extended.