From the dawn of civilization to the rise of serial car production, human/equine unity was of great military, economic and personal value. The horse was man's trusted friend and his dominant multiplier of strength and speed. In the twentieth century, however, this symbiosis declined and the era of chivalry came to an end. Equitation became the subject of different sports categories and, to today, remains the topic of opposing views. Only now, at the beginning of the twenty-first century, changes in the modern horse, brought on by usage-oriented breeding, begin to be fully recognized, understood and sorted out.
Contemporary controversies center not only on the horse's posture. Equine flexibility and its role in equitation also are reexamined. This flexibility has several aspects: The undulations of the equine spine; the horse's bascule over the jump; the horse's ability to bend laterally. Irregularities in spine and ribs impact the mounted horse's ability to be directed and to walk straight. The tendency to warp suggests bending. The question is when to bend the horse, why bend it and, to begin with, what is bending in the first place.
The horse's flexible middle section encompasses thorax vertebrae nine to sixteen. Part of this section are ribs nine to sixteen, the muscles that move and stabilize vertebrae and ribs as well as the dermatomes of the skin, which cover corresponding portions of the thorax. The middle section's flexibility impacts lungs, liver and ventral as well as dorsal colon portions, and their support from below. In the flexible middle section forehand and hindquarters merge.
Thorax nine to sixteen constitute the rider's seat. Between cranial and caudal portions of the dorsal serrate muscle there is a point of rest. On it the rider may sit at complete ease, while letting the world pass by his wondering eyes. As before mentioned the rider's seat bones are positioned atop thorax twelve and thirteen. His thighs rest on the overlap of cranial and caudal dorsal serrate portions between ribs eleven and twelve. The rider's seat is at once the center of equine flexibility.
A model of dermatomes in the horse's thorax
The horse's flexibility centers around thorax twelve and thirteen, mid-way between thorax five and lumbar one right under the rider's seat bones. Lumbar one like all six vertebrae of the lumbar region in addition to an upright process features two lateral bone extensions. The center of flexibility is supported by ribs twelve and thirteen, which as before mentioned are the longest ribs in the equine torso. Restrictions of flexibility in the mounted horse result from the closing of the croup. This restriction and its benefit for riding will be explored in more detail later.
Imagine a vertical plane, which cuts through the horse's torso between thorax twelve and thirteen. This plane would be right under the rider's seat bones, where also the horse's flexibility centers. If one considers this plane the separation of forehand and hindquarters, one is confronted with a puzzle. This model positions the majority of the horse's weight on the front legs. Only a small portion is supported by the hind legs. In locomotion this imbalance may be cleared by three powerful levers in the horse's hindquarters. Another model, however, which views the diaphragm at the separation of forehand and hindquarters not only hints at a different distribution. It refutes the notion of a middle hand in the equine body and points to a true position, which - so experience tells - permits the horse full command of its forces, while offering the rider control and ease.
Undulations of the equine backbone are easily observed. They begin when one hind leg moves forward and the backbone, via haunches and sacroiliac joints, begins to swing. This process results in the characteristic flow of the equine spine. As long as the sacral joint is open the unrestricted three-dimensional movement of the spine extends forward. There are two sets of vertebrae, which do not participate. Thorax one to four interface the movements of neck and front legs. The sacrum anchors the movement of the hind legs.
In the horse's flowing spine vertebrae rotate left/right and tilt fore/back. Only for split seconds are they in upright position. We will see that this uprightness characterizes the horse's straightness. The equine backbone permits these modulations. Vertebrae inherently are tensegrities, which stabilize from within and - based on a balance of tension and compression - allow for strength and elasticity. Equine ribs accompany the movements of the spine and participate in the undulations of the backbone, while spaces between them open and close.
Bending, turning, doing the job
"The horse's proper, well-established rib bending the rider recognizes at once as a safe, agreeable seat, which inclines towards the direction of movement". This statement by the famous 19th century German ecuyer Gustav Steinbrecht indicates a leaning of the mounted horse's spinal processes into the direction of movement. It denotes ribs, which lay flat in movement direction and bulge on the other side.
A similar much less pronounced inclination of spinal processes and ribs occurs with longitudinal bending (Längsbiegung). The latter comes about as a result of the horse's gaze into the direction of movement. The first vertebra of the neck in the poll moves laterally and initiates a soft lateral curvature of the spine head to tail. It is the horse's adjustment to the path of travel, - with or without rider. When the curvature's diameter gets smaller, the horse, in addition to the longitudinal bent, adjusts in the ribs and/or swings the hindquarters out.
Longitudinal bend and rib bending thus are fundamentally different calibrations in the horse's body. The former is a unilateral adjustment in the before mentioned tensegrity of the spine. The latter does not touch the spine but addresses the ribs. They rise and bulge on the horse's longer outside or descend and flatten on its shorter inside. The rider demands the latter with the touch of his calves, knees or thighs on ribs nine to twelve. The rendering of the ribs to the rider's inner leg is counter-calibrated by the touch of the rein on the opposite (that is on the outer) side of the neck. The rider guards the setting of the neck in the poll with his ring finger.
There are several indications for lee-way in bending, both laterally and vertically, in the horse's thorax between vertebrae nine and twelve. Spinal projections nine to twelve, relative to all others, are small and slender. They lean towards the rider. Spinal projections under the rider's bottom by contrast are short, broad and incline forward. In the horse's bascule over the jump vertebrae and spinal projections nine to twelve thus open - mind you - not under but right before the rider's seat bones. Ribs nine to twelve are free-bearing. They do not connect to the sternum. And they are not subject to the ventral serrate's thorax rising pull. Four retral attachments of the cranial dorsal serrate are strategically positioned to release ribs nine to twelve in bending. The rider's seat and his legs are perfectly placed between these features to direct and aid the horse under his seat.
But, the reader may ask, what about the rider's weight in the place of greatest flexibility? Does it not speak against the presence of a rider on the horse's back? The contrary applies. Horse and rider match in all details. It is the modern horse's warp that provides the problems.
The closing of the croup raises the rider's seat from aback. The elevation of neck and withers further secure the seat from afore. The center of flexibility at thorax twelve remains. It permits the horse to jump, climb and bend. And it allows the horse to offer the rider a comfortable seat. From the center of flexibility the horse turns shoulders, neck, head and eyes into the direction of movement. To do so it must be in elevation. A shortening of the base and resilient haunches are part of the process.
In elevation the warped modern horse stands a good chance to raise leaning spinal processes into upright position. It may thus overcome any undue restrictions in the undulations of the spine and any irregularities of shoulders and ribs, - and be straight. The horse's nature, its posture and the study of its biodynamics clearly propose this. Countless riders today and throughout the course of history confirm it.
In cheerful elevation
The modern horse's warp has caused havoc. Schools of equitation come and go. Some contemporary thinkers discard the very option of a center of flexibility in the horse's middle section as nonsense. They do not consider the horse's yielding in the ribs a need or feasability. To them rib bending is a phantom, created by generations of past German ecuyers. French masters make no explicit mention of either aspects of bending. No setting of the neck is mentioned in French equitation. French horses all the same, on curved lines, travel in longitudinal bent. The bend in the ribs on small circles.
Some contemporary riders suggest bending the horse in the transition from thorax to the lumbar area. The reader may realize the resulting damage to the functions of rib eighteen. The inclination of the flexible middle section's spinal processes into the direction of movement is debated by others. Several equine sports avoid bending the horse altogether. Others despite opposing views agree on one thing. The horse must be bent. If no where in the spine, at least the neck must be set to the side. One wonders why.
For all practical purposes a useful horse must give in the ribs. Why, after the initial release, it must bend systematically and repeatedly (or not) is addressed again in the next chapter, in context of the horse's power. Past generations achieved the release of the left ribs in what they considered the Zwangsseite ("coercive side") and re-adjustments in the right "problem side" with the input of spurs. Today, with a better understanding of reciprocities between movement, brain functions and awareness we use slow motions, which do the same, only better.
Turns on the haunches without interruption in the flow of movements are one. Taught from the ground they develop the horse's self-awareness. They provide opportunity for suppling. They introduce an element of play and establish the rider's leadership. They permit the observation of the horse and convey to it the responsibility to act on its own in accord with the rider's demand. They balance the horse and make it lively, dapper and focused. Why? They activate the gravity response systems at the root of movement.
Under saddle slow movements on small half-circles, alternated with short, supple phases of shoulder-in release the ribs. A shortening of the inside rein and the gentle turn of both thumbs in the direction of lateral movements permit the rider to sit and forbear from setting further signals. The rider's stillness and the figures' benefits limber and in due time establish the horse. The horse interprets the turning of the rider's thumbs on account of the distribution of dermatomes in the horse's and the rider's body.
Human dermatomes
