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Arc of Motion
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David Genadek
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 Posted: Sat Nov 20th, 2010 04:08 pm
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I have considered your question to me of what determines the horse arc of motion and I must say it has been a lot of fun to explore. An interesting intersection of the non physical to the physical and a constant balancing act between multiple elements in the complex equation that makes up the arc of motion. I have had to delve into my past and dig up the rules of movement I learned through gymnastics to begin to comprehend the increased complexity of a horizontally orientated animal.
It begins
The arc of motion begins in the world of emotion. Emotion stimulates a desire. The desire gives birth to an intent. The intent is focused through the eye . Where the eye looks the head will follow. where the head goes the body will follow.
Head versus body
There is a delicate balancing act between the head and the body. When the head is neutral the body will determine the arc of motion. When the head is not neutral the heads influence will be predominate. Consider standing at the edge of a pool with the pool being at your left side. If our head remained neutral and you jumped you would go straight up. If you did the same motion with your body and tipped your head toward the pool you would soon be wet. The third possibility is to allow the head to remain neutral and use the body to create the arc into the water. In this case you would you would not lift your left arm and would drive your right arm upward. This would create a much higher and smoother arc than would the tipping of the head.
As a gymnastics coach I know I have to train the mind of the gymnast to focus their intent and to always keep a neutral head position. You spot a gymnast until they can overcome the emotion of fear which creates a single minded desire to survive and confuses the original intent of the creation of a given motion. In the gym you learn quickly that your intent must be clear throughout a maneuver if you alter it you will crash.

The sacred head in horsemanship
Just as in the gym a riders aim should be to create enough support so that fear does not take over the mind of the horse and the head should always remain neutral so the bodies influence is predominate. The head is sacred, it should never be pulled on only guided so that the horse feels a sense of control so the intent of the motion does not get clouded by fear. When a rider can get the horse to listen to their intent over their own and they can support the horse with a neutral head the horses body will create the arc of motion in the direction of the intent effortlessly.
Horizontal VS Vertical
The first physical step in creating the arc of motion is the lifting of the front of the body. This is difficult for a vertical creature to comprehend as their body begins in a lifted position. However, if the vertical creature were to touch their toes and then try to take a step forward they would quickly find that it is very difficult to create an arc of motion in this position . Horses know this is how they move. However, they were not designed to have people on their backs and this precisely why the five essential are essential. It is contingent on the rider to teach the horse how to create it's arc of motion with weight on its back. the rider can do this by supporting the horse in straightness, engaging the hind quarter, lifting the root of his neck. These three elements will create the initial arc and or the vertical amplitude of the arc. The horse must then be able to maintain his ability to generate his arc of motion moving forward by continually maintaining a weight bearing posture. The second the horse loses his weight bearing posture he loses his ability to create an arc of motion. Finally by bending in his rib cage he can direct the arc laterally.
The conformation of the horse will determine the limits of his arc of motion. One o f the factors of the limits will be the ratios of the animals spinal sections. In the horse we end up with 15 ratios that will begin to define limits of a given horse arc of motion. Those 15 ratios are shown in the table appended below.

In addition we have the ratio of the length of the dorsal ligament to the different sections of the spine which will be largely defined by the height and angle of the dorsal processes in the Thoraciac, Lumbar and Sacral sections and the Lamellar sheet in the cervical section.

David Genadek


Attachment: Fibonacci table.jpg (Downloaded 334 times)

DrDeb
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 Posted: Mon Nov 22nd, 2010 08:37 am
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David, no question that there are a lot of good ideas packaged in your post. They will be obscure to most readers, however, because our readers here have not been party to our private telephone conversations over the past 20 years!

So, rather than be obscure, either to them or with you, I offer the following:

1. For the benefit of our readers I first wish to define what 'the arc of motion' is -- it is the arc described by the animal's whole body during leaped gaits. Leaped gaits, also called suspended gaits, are gaits that have one or more periods of suspension built in -- i.e. for example trot, canter, saltation, or pronking; in short, they are gaits with 'bounce'. So the question can be restated as 'how does an animal with some kind of a bounce in his gait generate that bounce.' Despite my longstanding interest in all things related to the horse's spine, the answer has very little to do with the spine. The key word here being CREATE as opposed to 'regulate' or 'modulate'.

2. The part of the anatomy that creates the bounce, and thus gives the power to push the animal's body up away from the earth, is the hindquarters primarily, and secondarily, at least in some animals at some times, the forequarters. In other words -- it is the overall size (the 'scale') of the animal; the within-limb proportions of the bones; and the sizes and attachments of the muscles investing those bones, that create the thrust that allows any arc of motion at all.

3. Horses are a good example, actually the world's foremost example, of an animal with cursorial limb proportions. This means an animal in which the distal portions of the limbs are elongated compared to the proximal portions of the same limbs. This phenomenon is referred to by zoologists as 'limb telescoping.' The illustrations from Gyorgyi Doczi's "The Power of Limits" appended below show this graphically. The opposite may be seen in the elephant, which is the world's foremost example of an animal with graviportal limb proportions. In the elephant, the proximal limb bones such as the humerus and femur are long, while the metacarpal and metatarsal bones are short.

4. The limbs of any mammal can be thought of as being set into a particular gear -- in other words, we can usefully make that analogy. So for example, animals such as the armadillo or the mole, for which the ability to dig with the forelimbs is crucial, have proportionately huge paws (that act like shovels) powered by muscles which attach low on the individual bones, thus giving maximum leverage. Joints between the bones are also set to produce power rather than speed; in other words, they are set in 'first gear' or 'granny low'. In the mole, for example, the olecranon process, which is the part of the ulna that extends past the elbow joint and to which the triceps muscle attaches, actually exceeds the length of the part of the ulna that is distal to the elbow joint. The opposite obtains in an animal such as the horse which has telescoped limbs: here the olecranon process is very short compared to the distal portion of the ulna, and thanks to this the triceps muscle produces a whipping motion of the distal limb whenever it contracts. The horse thus finds itself permanently in 'fifth'.

5. The problem for the ridden horse is thus to produce suspended gaits with ENOUGH suspension; upward motion is more difficult for the horse to produce, especially when it is carrying a rider, than forward motion is. Likewise, SLOW versions of any gait are more demanding of the horse than to go fast. The faster a horse moves at any gait, the lower the arc of motion. This is referred to as “efficiency of stride”, because the body is thrust upward to a minimum amount while it moves forward to a maximum amount, i.e. the arc of motion is low but long. However, in the pleasure horse as opposed to the racehorse, what we want is not a strengthening of the natural locomotory propensities of the horse, but rather to develop his ability to thrust weight upward – his own weight plus the rider’s. We also often desire that he should produce the trot and canter gaits as slowly as possible. These two things – to produce an arc of motion that is shorter and higher, and to progress forward more slowly as measured in miles per hour – require that the loins be coiled, the freespan of the back be raised, and the base of the neck be raised. In other words, the higher and shorter the arc of motion, the more collected the horse; and the more collected the horse, the higher and shorter will be the arc of motion – whichever way you like to think of it. Collection requires peculiar strength, because what we are doing when we train the horse to collect and condition him so that he has the requisite strength, is equivalent to taking a car that is stuck in fifth gear and, not by changing gears but by greatly increasing the power of the engine, giving it the capability to start heavy loads without lugging the engine, as well as tow them at highway speed. How’s that for sophisticated double clutching!

6. The first part of its body that any horse – green or trained -- moves, when it starts from a halt into a walk, is that it lifts its back (i.e. it coils its loins, which is instantly reflected by a slight dipping of the haunches and simultaneous arching of the freespan). Note that he stands upon one or both hind limbs as he does this; he pushes down on the limb(s); and that if it were not for this activity of the muscles of the hind limb, no cantilevering of the fore part of the body would be possible. The animal coils its loins because in order to start the weight forward, it must also be able to lighten the forehand, i.e. cantilever, enough to lift at least one forelimb. As horses become more trained, the initial lift, as well as all other lifts, become more powerful, so that at an ultimate the animal becomes capable of things such as transitioning directly from a halt into a canter whose lead has been specified by the rider ahead of time. This is what ‘lightening the forehand’ means, and it of course involves and requires the lifting of the base of the neck just as much as it involves the anchoring of the hind limb(s) and the coiling of the loins. The last competency that a horse acquires as it learns to make its arc of motion shorter and higher is to raise the base of the neck as a result of a sufficiently deep coiling of the loins.

7. I like and agree with your ideas about the effects of fear. What I hear you saying is: (a) fear creates bodily tension, which interferes with balance; (b) lack of balance promotes ‘grabbing up’ which adds still more tension, i.e. a vicious circle. A ‘neutral’ head I take to mean a head attached to the end of a neck which is not carrying any brace, i.e. the justification for twirling the head. Very true then what you note, that when there is a brace in the neck and also continuous backward traction on the reins, the horse cannot coordinate the rest of its body very well. It loses track of its feet, and, like a semi trailer truck that’s locked up the brakes, the hindquarter skids out without the driver being able to do much to prevent it or regulate it. This is all why François Baucher said in 1842 that we ought to learn and practice what he called ‘jaw flexions’, of which my ‘head twirling’ is but a version adapted for horses at liberty or accustomed to go in today’s simpler and usually gentler bits. By the ‘sacredness’ of the head I take you to be speaking hyperbolically. The head is not really sacred, but certainly, one might have to tell a student who has been long in the habit of pulling to loosen up or even, for a temporary period, completely go to the buckle.

8. Your table of proportions would be interesting to fill in with actual measurements. As soon as I saw it, I was reminded of Györgyi Doczi’s wonderful and thought-provoking book “The Power of Limits”. I have owned this book since college days and thought many times that there ought to be some scientific use for the Golden Proportions theories he explains and illustrates. And of course this has proven to be so: for the Golden Proportions derive from the famous mathematical progression called the Fibonacci Series, which gave rise to Benoit Mandelbrot’s formulas, which are part of what is now called Chaos Theory. Today, chaos calculators are used to produce and analyze maps, design bridges, improve radio and TV transmission, and write sophisticated computer code, among other applications. For our readers who aren’t familiar with the Fibonacci Series, here is the beginning of it. It is built from the number 1 by adding the number to itself, and then adding each number in the series to the one coming before it in order to create the next number:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89 ….

The ‘Golden’ proportions are the ratios 3 : 5 and 5 : 8. What Doczi points out is they can be detected among the anatomical parts of many different kinds of plants and animals, not in horses only but in shells, sunflowers, trees, and the skeletons of all kinds of animals from dinosaurs to frogs to people. It can be detected in faces, horses’ hooves, and the wings of birds. However, some ‘fudging’ is usually necessary, because creatures almost always have some little quirk or other which causes them not to quite conform to any nice neat clean mathematical theory. What DOES conform precisely is architecture or anything else thoughtfully built by humans – the most famous and ‘human friendly’ construction always incorporates ‘golden’ proportionality, i.e. in the height X length of rooms, the height X width of window apertures, in the width X length of floors, and among the girders that structure bridges. The world’s most famous structures, including the Parthenon, the Eiffel Tower, the Lincoln Monument, the Taj Mahal, and Frank Lloyd Wright’s ‘Falling Water’ house all give multiple examples of golden proportions. For some reason which is a mystery to me, humans perceive these proportions as beautiful; just being in a room or a building built to these proportions gives most people a sense of peace and serenity, so that they want to be there. Is this because similar golden proportions are found everywhere in nature, and we thus retain some deep memory and desire for them? Or is it just a human quirk that forces us to SEE these proportions whether we will or no, as a dog is ‘forced’ to be acutely aware of smells? For it is also true that not every natural object exhibits golden proportionality.

9. Once again, I suggest that anyone interested in biomechanics obtain a copy of Milton Hildebrand’s “Analysis of Vertebrate Structure”, obtainable from Amazon.com and the like. This is the most important, complete, and well-illustrated book on the subject and a must-read for anyone who wants to learn the anatomy and physical principles that govern cursorial, graviportal and saltatorial locomotion, and pronking, digging, and swinging from trees in a manner akin to gymnasts. – Cheers – Dr. Deb

Attachment: Fibonacci skeleton Doczi.jpg (Downloaded 326 times)

CarolineTwoPonies
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 Posted: Wed Nov 24th, 2010 07:02 am
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A lot of this is very complex to me but I understand the point about fear I think. I was thinking it is the same logic found in how the training of the horse is described in the fei's article 401: "the rider aims to develop a horse that is calm, keen, attentive, confident and supple, loose and flexible." It seems that the first 4 attributes all have to do with trust -elimination of fear, anxiety, stress - so that the body can function without rigidity and be all the things that allow for balance, motion and suspension: ie: suppleness, flexibility and looseness. I really appreciate when I can relate concrete biomenchanics information like what I learn from you and the guidelines for training horses per the fei, your work illuminates parts of that text for me. Have you written on this subject in the past and if so where could I find your work?

Last edited on Wed Nov 24th, 2010 07:04 am by CarolineTwoPonies

Helen
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 Posted: Wed Nov 24th, 2010 10:33 am
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I'm currently rereading my Birdie Book and one part of what you said was suddenly illustrated at just where I was up to: In chapter 10, on page 58, photo C of the bay mare is a perfect example of "leading with the head" - the rest of her body has to simply lean through the turn to keep up.

To compare, there are some lovely photos a couple of pages later of horses turning with 'neutral' heads as you put it, Dave. I especially like photo A of DD & Painty turning left.

Here is the bay mare - I'm sorry if this isn't OK to reproduce DD, just take it down.

Attachment: phpwMnnKPAM.jpg (Downloaded 240 times)

DrDeb
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 Posted: Wed Nov 24th, 2010 07:35 pm
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Caroline and Helen -- Yes, Caroline, some of what Dave is investigating does get into some rather arcane stuff. Really, though, it isn't inaccessible; Doczi's book was written for the popular-science readership and is sold through Amazon.com. I promise it's a completely fascinating read -- the problem in my mind with it not being that it's too hard to understand but rather that it's such an enormous thing and enormously important, then how to put it to use. It's like trying to find "a use" for sunshine or the sea!

As to whether I've ever commented upon the FEI handbook in print, yes indeed, in two main places: one, the Birdie Book (see the introductory chapter particularly), and in the "Inner Horseman" disk for 2005, where I dissect in detail the differences between classical horsemanship and competitive dressage.

And Helen, as to your post -- really I wouldn't prefer that anybody dub stuff out of the BB for posting here. Much would I rather they read the book! Nonetheless I will leave the image as being germaine to David's observation about the head "leading". But remember, the head only APPEARS to lead because of its lack of independence from the rest of the body. It cannot move separately when there is a brace in the NECK. So our objective, through jaw flexions/head twirling, is to get rid of the brace in the neck. And our objective, in understanding Birdie Theory, is to get rid of the fear which can cause the whole body to brace up.

The horse you post is running -- not without some apprehension -- in a roundpen. She's at a clinic where some of her problems were being addressed, and she's doing no more, and no different, than 99% of horses will do when they run within the confines of the roundpen. The roundpen here is 55 ft. in diameter, and this is too small for this particular mare given her state of bodily stiffness or braceyness. In short, when the picture was shot she did not know, and would also probably have been unable, to flex to this small of a curve.

I attach a photo of Oliver and me taken on Sept. 30th of this year, so that you may examine in detail the differences between what a trained horse moving in relaxed balance does vs. the green and somewhat apprehensive horse in the first photo. Oliver is not moving quite as fast as the mare; she's galloping, while he is in gait (stepping pace). Nonetheless, the comparison still brings out the salient points. Particularly, you should note the GLOBAL effect that stepping under the body shadow with the inside hind leg has. It is the inside hind leg that creates the flexure in Oliver's ribcage. Note also the completely different balance of the fore part of the body, particularly, that the mass of the shoulder-block is displaced to the outside in Oliver, but carried so far to the inside in the mare that she actually has to cross her forelegs.

For obvious reasons, we do not want a riding horse to move like the mare; she must learn a different way to travel, one that accommodates and considers the rider, while still being fine for her, or even (as it actually is) physically beneficial.

I will also say of this photo that it is unfortunate that I'm looking down and in. I often coach my own students not to do this. Notice how my wrong focus causes my head to tilt and also my body to more subtly tilt inward. This does nothing but drag Oliver off his balance -- even though my legs and hands are telling him to bend, my body is not helping! Therefore he does not have as deep a bend in this photo as he would be capable of if I had been sitting properly. -- Dr. Deb

 

Attachment: Oliver and Deb turning in gait cprsd.jpg (Downloaded 219 times)

David Genadek
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 Posted: Sun Nov 28th, 2010 12:05 am
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I thought it might be helpful to go back through some of my thought process on this. It began with these pictures of deer and one of the posts here on the horses neck. This brought up the subject of pronking.


One of the things that immediately jumped out at me in a horses neck versus the deer neck was the ratio of nuchal ligament length to cervical chain length. It made sense in my mind that this would be a major factor in why the deer can pronk and the horse cannot. The deer the ratio of nuchal ligament length to cervical chain link is nearly 1 but on the horse is less than one. This means that when the deer lifts the base of his neck it encounters no limit imposed by the nuchal ligament length and as such can go straight up without causing a forward arc. In the horses neck the nuchal ligament will create limit after which point the straightening of the cervical chain will cause a forward arc. This thought gave me some insight into the role of the neck and the arc of motion but clearly what began the process started somewhere else.
I had to ask myself what made me go in one direction or another. So I took one step and asked myself what happened. I realized by taking one step forward I could go in multiple directions in. What was happening with my body had less to do with the direction I would take than the intangible thing that was actually creating my direction. If I were sitting on the couch and I smelled cookies in the kitchen it would stir all the wonderful emotions of fresh baked cookies and from that would be born a desire to go eat one and from that desire the motion would be created.
From that point I began thinking of back handsprings in the gym because they are done in an arc. A back handsprings when properly done is generated by the legs. Thinking back and how I used to teach kids to tumble I realized I began that process by making them conscious of what they did to take a step forward. If anyone tries this you will soon realize that you begin walking by leaning forward. This led me to ask the question how would horse lean forward? Horses horizontal so before he can fall forward he has to lift the front of his body. He begins the process by engaging h is hind quarter and utilizing the passive dorsal ligament system to tension the system that will allow him to lift his front end. Clearly when you look at that system it becomes apparent that the angulation of spinal processes creates a reciprocation, in other words if I move one thing other things are going to have to move. When I go to a real horse and ask him to engage his hind quarters and watch the reciprocation in action it seems to reciprocate to the anticlinal vertebrae when I asked the horse to drop his header lift the base of his neck the reciprocation once again seems to end at the anticlinal vertebrae. So all this brings more questions to mind. What is the purpose of the inclination of the spinal processes? What role does the anticlinal vertebrae play? Is it the angles of the spinal processes that are determining the pattern of reciprocation in part or in whole? What role does the length of the spinal processes have in creating patterns of reciprocation? What role do these reciprocating patterns play in the overall movement of the horse? Why are their bony connections from the dorsal ligament to the centra in the thoracic lumbar and sacral sections but a flexible laminar sheet on the cervical section? What role do the curves of the spine play in the system? What effect would the proportional differences have on the horses overall ability to create an arc of motion? What is the relationship between all the ratios that are created through the different combinations of spinal sections, spinal process length and angle and dorsal ligament length relative to spinal section length?
In pondering these questions I came to the realization that even in a given animal with all the variables fixed by the horses conformation that in the spine the ratios remain variable . In the spine the conformation sets the limits of a range of ratios whereas in a leg the ratios of bone length create very finite ratios. Here is a picture of a lumbar span shot first with no upward flexation to it and then I arced it upward as It would be when a horse engaged it's hind quarter. The distance between the spinal processes changed the length by over a half inch. So we have what I would have to guess percentage wise is a significant change in the ratio of centra chain length to dorsal ligament length. This has me wondering if this whole spinal system would function properly if the dorsal ligament was white ligament instead of yellow ligament? What would happen in the leg if you could change the link of any of the bones by 6% in midstride? Of course you could not use such a construction on the leg is it would not hold up to the weight-bearing but nonetheless a fun theoretical thought.


I have been struggling with the notion of a neutral head. Interestingly this is a cornerstone of every move in gymnastics and every gymnast in the world is preached this from the very second they walk into the gym. So although I have a sense of this in my body and know exactly what I mean by this putting it into words is problematic. I hesitate to use the word tension because in any posture there is essential tension. So thinking back to my own body in neutral head is what happens when you create a postural frame with all the essential tightening and the head ends up where it does as a result of the shaping of the body. The head is out of neutral when it's position affects the shaping of the body. Saying it another way your head is neutral when it's position is determined from the bottom up or back to front on a horizontal creature. Now I must ask the gym gods for forgiveness for all the times I whacked the kids on the head while trying to teach them to do a handstand. I should've gotten them to activate their cores and then there heads would've just done what they needed to do.

David Genadek

Dorothy
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 Posted: Tue Nov 30th, 2010 05:56 pm
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Hello David, Dr Deb and readers,

David talks about gymnasts and the position of the head being influenced by the core. I am attaching link to a video that I came across on Facebook which shows two men - I guess they must have a background in gymnastics. The routine they show demonstrates extraordinary core strength and power. Every movement they make is done 'one step at at time'. I get the sense that they could stop moving at any moment and would remain in balance at every point in the poses they strike.

I hope that this is not too far OT, but I am awestruck that human bodies can be so powerful and controlled. Please delete this, Dr Deb, if you feel it is inappropriate.

The link takes you to a page on my facebook, I could not find out how to link to the video only, so please ignore the comments underneath!

Dorothy

http://www.facebook.com/video/video.php?v=134593293243670#!/permalink.php?story_fbid=172640589422084&id=623561933

David Genadek
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 Posted: Tue Nov 30th, 2010 06:34 pm
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Dorothy,
Actually on his first hand stand his head is out of neutral and because of that both are using a lot strength and having to make a lot of subtle adjustments. If he just looked out of the tops of his eyes that first handstand could look effortless. If he were swinging on a high bar and had his head was in that position he would not go over the top. On that first move I would say there is more than essential tightening going on.
This makes me think of tight rope walking. When you are on a tight rope any time you have any tension beyond what is essential the cable will start to wobble uncontrollably. It is very cool immediate feed back. Hmmm how to get people and their horse on a tight rope.....
David Genadek

Dorothy
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 Posted: Tue Nov 30th, 2010 07:04 pm
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Hello David,

I shall watch again with your comments in mind!

Dorothy


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