How a rider interferes with the canter...

In the table below, the Muybridge rider is shown compared with the natural canter of a dressage horse. These legacy images make it clear that a rider braced against the motion of the horse interferes with balance, phasing of the stride and mobility. Although the interest at the time the images were made was a question about whether or not horses had a moment of suspension in their gaits, here we are interested in the effect of the rider on the horse. Because these images are often cited and have even been used to develop concepts of some gaits, it is worth noting the negative character of the rider on the purity of the gait.

For dressage riders, the trailing hindquarters, open mouth, hollow back and "teapot neck" will be obvious. Note also the inability of the ridden horse to stabilize its neck and spine with the complexus group of muscles.

What may not be so obvious is that the loss of connected posture and correct timing of steps in a stride (see in particular M4 below) not only destabilizes the horse but interferes with the biomechanics of the connective tissue (fascia, ligaments especially) and muscles to balance the horse while it moves forward in straightness.

FROM THE LEGACY WEB SITE: On June 15, 1878, a clear and sunny day in Palo Alto, California, amid a gathering of art and sports journalists, Eadweard Muybridge photographed the first successful **serial images** of fast motion. [The subject of these photographs was the trotting horse, Abe Edgington, harnessed to a sulky. The horse was owned by railroad builder and former governor, Leland Stanford. **Proven was Stanford's theory that during a horse's running stride, there is a moment of suspension where no hooves are touching the ground.** What had begun as a topic of unresolvable debate among artists and horse enthusiasts now launched a new era in photography. The components required that day included twelve cameras, equipped with "fast" stereo lenses and an electrically-controlled mechanism to operate the cameras' special shutters. Wires laid underground along the track at 21-inch intervals released the shutter of each camera as the wheels of the sulky made contact.
M1 BELOW: Muybridge images of left canter seen from right side.	M2	M3	M4 Right fore off ground, on two left legs & unstable.	M5 Inside fore past mid stance, hind legs trail out of phase, especially outside hind.	M6 Suspension: legs sprawling and not held close under center of mass.

BELOW: Rio Sereno: right canter seen from right side.	2	3	4	5	6

Separation of hind limbs indicates greater engagement, as does angle of pelvis.	Phasing of legs places the stride more under the body than the horse above.	Diagonal pair placed more effectively under the hip for propulsion.	Three legs still on ground, in triad of support.	Inside fore at mid stance, outside hind leg in phase.	Suspension: legs held close under approximate center of mass (white dot).

It is characteristic of efficient, balanced and properly phased dressage gaits that the limbs are managed close to the center of mass and track without crossing fore and aft when seen from behind. Tracking straight keeps the masses of the legs from causing the horse to sway. In the walk, this swaying out of the fore and aft plane manifests itself as "rope walking." In passage and piaffe, swaying side to side as legs cross over while traveling straight is called "balancé."



Some PASSIVE connective tissues that provide balance of thrust with stable navigational capacity.	Some of the muscles that ACTIVELY move the limbs.