Inverse dynamics and the science of equine movement

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Manchester
Manchester

For two or three millennia, visual examination has been the main clinical tool for diagnosis of lameness, quality of the gaits or athletic predispositions of the horse. In the last two decades, kinematics and kinetics analysis have enhanced our understanding of the gaits.

But variables such as limb trajectories, joint angles and angular velocities contain basically the same information that is observed by the eye of an experienced breeder or trainer. A more powerful method is analyzing movements and forces simultaneously using Newton’s law of dynamics.

Riding and training and performing is not postural. It is about producing and managing forces. When the management of the force producing motion is incorrect and an injury is caused, only by recreating proper function of the horse’s physique – therefore proper motion – can soundness be restored. The promise is great. Many injuries can be prevented. Many “irreversible’ damages in the view of conventional approaches, can be reversed. Many resistances of the horse and difficulties to perform can be amended. There is another world and a much better world but it is in this one. It demands the evolution from superficial thinking and acting, to deep respect for the horse, respect for the students and therefore a training and a teaching updated to actual knowledge.

John Naisbitt wrote: “We are drowning in information but starved for knowledge.”

In a world where marketing prevails, science is used as a selling tool and theories are promoted claiming scientific reference even when such references are partial or distorted to benefit the product that promoters want to sell. There have been recently the promise that a hyoid apparatus would act on the horse’s back and that the lowering of the neck was producing endorphins.

In a more serious study, Understanding the perceptual world of the horse, Carol A. Saslow explains that the release of opoid neurochemicals called “endorphins” occurs whatever the neck posture. An interesting observation is that, “the highest level of beta-endorphin occurs in early morning and correlates with decrease nociceptive (pain) sensitivity at that time.” Perhaps, in order to be more accurate, promoters of the low neck/endorphins theory should advise lowering the neck between 6.05 and 7.14 am.

Isaac Newton (1642-1727), formulated the basic law of dynamics, establishing a relationship between force, mass and translational motion. The laws of dynamics allow predicting and measuring motion when the intensity of the force is known. This is referred to as “forward dynamics”. At the contrary, “inverse dynamics” is about estimating the forces that were the cause of an observed motion. Proponents of superficial equitation will raise their eyebrows thinking: “How this is going to make me win a blue ribbon?” It will not but it might prevent the horse from injury.

In humans for instance, a very well-known finding is that knee extensor moments during gait are significantly reduced after anterior cruciate ligament injury. Inverted dynamic analysis provides a tool to monitor patient progress during rehabilitation. This type of practice is not commonly used in equine rehabilitation, but the results of these studies support the main concept of the Science of Motion’s rehabilitation technique “Perfect hoof placement”. The formula is not limited to the hoof; this is just a phrase. The therapy is about creating perfect placement of the joint or alignment of the joints at impact and during the stance. In human rehabilitation, a certain bracing method reduces the medial compartment load on the knee joint. The human knee is the horse stifle and applying the findings, we have observed that perfect stifle placement at impact and during the support phase accelerated the horse’s rehabilitation.

manchester2

Manchester had severe damage on the anterior cruciate ligament of the left stifle. It is by applying the above technique that we restored soundness. We used Manchester as a school horse for our teaching program once he was sound, and he was loved by each student who rode him.

He is 18.2 and weighs 1800 pounds. A very powerful and very kind horse, he gave students the feeling of absolute lightness on the bit, on the legs, on the seat and very high suspension. Superficial thinking will theorize that we manipulated the joint or the leg to get results as this is the way the equestrian world is used to think. There is a better world but it is deeper.

The biomechanics of the vertebral column, although very complex, are of vital importance because they form the basis of all body movement”. (Leo Jeffcott, Natural rigidity of the horse’s back bone, 1980). Proper placement of the stifle joint at impact and during the stance depends directly on functional or dysfunctional mechanism of the vertebral column.

manchester3Manchester was dysfunctional as he traveled with a strong right lateral bending that was coupled with an inverted rotation. The spine dysfunction placed the pelvis in an oblique posture, altering proper kinematics of both hind limbs. The left stifle was weaker and the damage started there. Whatever treatment was done was ineffective as long as the scoliosis of the thoracic spine and the muscular imbalance creating inverted rotation was identified, addressed and corrected. The horse was lame for eight years before he came to us. Nothing worked because the same stress damaged the same ligament as soon as the horse was set in motion.

Working hip or knee extensors muscles did not work either.  Liduin S, Meershoek and Anton J. van den Bogert write in Mechanical Analysis of Locomotion (2003) that “the horse, whose four multi-jointed limbs frequently act as close-chain mechanisms, may redistribute its joint movements without visual gait changes. For instance, a visually identical hind limb extension in late stance may be accomplished by only hip extensors muscles, only knee extensor muscles or any combination of these. Inverse dynamic analysis allows to ‘see’ these differences in muscle coordination.”

We did not have, at the farm, the capacity of inverse dynamics analysis. The software is available in vet school research programs and it is very complex mathematical work. Only specialized experts can complete such work. However, watching over and over kinematic analysis of the stifle and results of inverse dynamics, it became possible to develop an eye for proper stifle movement. The feeling was also a major asset. Our therapy is always done in motion, combining in -hand work and riding. The combination of visual impression and physical perception provides a better ground for sound analysis.  The first part of the rehabilitation focused on correcting the dysfunction of the back muscles. It was done riding the horse using different levels of balance, straightness and exercises. Once sound alignment and functioning of the thoracolumbar spine was recreated, the work refined the mechanics of the vertebral column until thoracolumbar motion, pelvis motion and consequently stifle motion became correct.

It was a lot of “try and think and try again”, and Manchester’s participation was superb. At first he reacted by protecting the problem area, but once Manchester explored a specific flexion of the thoracic spine that changed the angle of the pelvis and consequently the stifle alignment, the work took on a different dimension. As I felt the reaction and ease of the left stifle, I was thinking about the human study, talking about a certain bracing method, reducing the medial compartment load on the knee joint. I probably had created the same phenomenon with the horse.

I approach the next day’s training session hoping that I could recreate the same proper alignment. Manchester has done his homework, too. His psychology was no longer protecting his stifle but letting me guide him towards proper coordination. Therapy in motion is not about moving a joint. It is about creating an overall body coordination allowing proper use of the joint. This cannot be done without the horse “getting it”. There is a lot to say about that because before finding the right coordination, the horse makes mistakes and if the horse became afraid of error and reprimand, he will never explore beyond natural reflexes, which are protecting the problem and not addressing and correcting it.

There is another world but it is in this one. It is deeper than the superficial world that we are trained to see and believe. It demands a higher level of thinking. During Manchester’s rehabilitation, I had the thought that if I walked backward during the in hand work, I could see the stifle. Rational but simplistic.

academic-equitationIt was the proper functioning of Mancheser’s thoracolumbar spine that created perfect stifle placement at impact and during the stance. By facing the back, my back was not working properly and Manchester became confused. The in-hand work that we do has nothing to do with the type of in-hand work commonly promoted. Our approach is inspired by General Decarpentry work in hand but adapted to actual knowledge. We do not use obedience and conditioned reflexes such as the whip touching the horse chest. We use the fact that when trained to do it, horses are capable of perceiving the energy that the rider creates through nuances in the tone of the abdominal and back muscles.

We do not work between the hands and the whip, which can only teach gestures. We work back to back. Once the horse is in tune with the rider’s back, it becomes possible to create greater sophistication of the horse’s thoracolumar mechanism. This is of course a gross simplification. The work is very precise, very sophisticated and immensely interesting. Facing the back did not allow subtle work and coordination of my own back and abdominal muscles and Manchester did not feel the dialogue anymore. It was logical for the superficial world to look at the stifle.

It was disturbing for the other world, the one where the horse is comfortable to live in.

scienceofmotion.com

Jean Luc’s Inhand Therapy Course

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Jean Luc Cornille

Jean Luc Cornille M.A.(M.Phil) has gained worldwide recognition by applying practical science to the training of the equine athlete. Influenced by his background as a gymnast, Jean Luc deeply understands how equine training can be enhanced by contemporary scientific research. A unique combination of riding skill, training experience and extensive knowledge of the equine physiology enables Jean Luc to “translate” scientific insights into a language comprehensible to both horse and rider. This approach has been the trademark of his training. – read more about Jean Luc

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