Moving Horses

You can take the title of this blog as meaning either or both of two things:  horses that are moving (in which case the word “moving” is an adjective), or the things a person does to move a horse (in which case the word “moving” is a gerund).  The two things are related, which will turn out to be the theme of this blog.

This entry is the joint product of two people:  myself as the anatomist and biomechanics scientist, and my business partner Jo Belasco as professional trainer. Jo and I have worked on what might be called “applied horse biomechanics” together for over ten years now, and although I wrote the words you see here, they only came into existence after lengthy conversations with her and discussion about this very post.

The impetus for writing this entry was that a horse friend wrote me in response to my post about the walk, saying that although he’s heard many trainers insist that a horse cannot move the leg it’s standing on, and that cues to move a specific foot need to be provided when that foot is off the ground, he doesn’t see how this can be so.  “If it were true,” he wrote, “there would be no way to start a horse from the stop.  Maybe the ‘rein or seat’ qualifiers are important here, but I had a horse that was so forward he would move if you simply relaxed the reins. . . All with no reference to influence with the foot on or off the ground.”

My friend’s comments made me think about the glib way we all short-cut biology to smoosh terms around in ways that give them meaning they were never meant to have, and the impact such short-cuts have on how we think about and deal with horses.  So here’s some additional thought about the walk and the training practice of learning to cue a horse’s foot when it’s off the ground.

When people say you can’t move a horse’s foot unless it’s not on the ground at the time, they are really making a short-cut statement.  The real statement should be:  “If you cue a horse to move its foot when that foot is bearing weight at the time, the horse won’t be able to respond immediately and/or in the way you’ve asked.  And because horses move quickly, even at a walk, if you cue them any later than the moment you feel their foot come up, you will be too late.  They will have put their foot back on the ground before they have a chance to respond.  Furthermore, you want to cue them early enough that their foot is not only still in the air, but able to be redirected to come down somewhere else than where it would have gone otherwise.”  Yes, that’s a lot to say, but of course it’s why we speak in a short-cut.

Let’s consider, first, where this idea comes from, which is ostensibly the nature of the step cycle.  A step cycle is the complete range of motion made by a limb from the time it leaves the ground to begin a step, through the time it advances and comes down again to the ground and bears weight, until it leaves the ground again to take a new step.  The sequence of still images below shows one complete step cycle of the left hind limb of the same horse that was pictured in the walking blog I posted on October 12.  The screen grabs are from the same slow-motion video I used there.  The blue arrow I’ve added to the first frame shows the foot coming up off the ground to begin the step cycle.  It’s a little hard to see that the heel is up in that image because of the way I reduced it to fit on the page.  But the heel is up off the ground where the blue arrow is.

1. Left hind foot comes up from the ground as right front starts to come down and be placed.

2. Left hind foot is clearly no longer supporting weight. Weight is now on the other 3 legs.

3. Left hind foot is now being brought forward again, though toe is neary dragging on the ground in this horse.

4. Left rear continues to come forward, now passing in front of the right rear foot (which remains in place, here).

5. Left rear moves a lot farther forward and approaches the ground

6. Left rear foot is placed on the ground, well in front of right rear foot.

7. Left rear foot is bearing weight as right rear foot now comes up. (Left front is coming down, so notice that weight is presently on only two feet.)

8. Left rear foot is still weight-bearing, but right rear foot is now being brought in front of it. Weight is on 3 feet at this time.

9. Left rear foot still weight-bearing but body is now being thrust in front of that foot as right rear foot approaches the ground.

10. Left rear foot is now behind the horse but still fully flat on the ground.

11. As horse prepares to lower right front foot to the ground, weight begins to shift off of left hind foot, though it is still on the ground.

12. Left rear foot begins to come up from the ground as right front foot touches down. This is just barely past the same part of the step cycle shown in picture 1.

You will notice several things in this sequence, if you look closely, all of which give you a little better understanding of the walk.  First, the horse is moving its body forward (the whole point of walking) by pushing the foot back against the ground during part of the step cycle.  So the position of the foot we’re watching changes with respect to where the horse is.  When the foot is coming up off the ground in the first frame, it looks to be about 4 feet to our right of the vertical wooden post, which is at that time behind the middle of the horse’s neck.  Mid-way through the step cycle, in frames 6 – 9, the horse’s left hind foot is fully on the ground and supporting weight.  It has been brought forward about 2 feet, so now it is only about 2 feet to the right of that post.  At this point, the post is behind the horse’s withers (in 6) and then the end of the back (9).  By the time we get to the last frame, where this back left foot comes up off the ground again, it’s still about 2 feet to the right of the post — but now the horse has advanced so far forward that the post is behind its rump.

Many trainers say a rider could ask this horse to move that back left foot in about frames 1 through 3, when it’s come up off the ground and has not yet been set back down.  So they teach riders “feel” of the feet so they can tell when that particular foot is in the position shown in frames 1 through 3 — and that’s when they cue the horse to set that foot down someplace other than they were about to put it.  These trainers believe that if the horse is asked to redirect that foot between frames 6 and 11, the horse won’t be able to respond even if it wants to because it is standing on that foot and therefore unable to move it (unless it breaks its gait by hitching or stumbling). In the case where you are asking a loping or cantering horse to change its lead, there is even the possibility that it will respond on one end (that can respond at that moment) but not the other (which can’t), with the result that it cross-leads if you ask for a change of lead while the back foot that needs to move is on the ground.

Because of my biological background, I was actually suspicious of this idea for quite a while.  The reason is that neurological researchers spend a lot of time considering what they call Reaction Time (or “RT”, because of course it has to have a catchier and geekier name than just “Reaction Time” if you study it in your lab).  To get an idea of the level of discussion about how long it takes a body part to respond to a stimulus, and the kinds of factors that impact this response, here are abstracts of a couple of scientific papers on the subject from the National Academies of Science and the American Psychological Association.  What you will see, besides the designation “RT” and other jargon that might make you reach for a pain reliever, is that moving a foot in response to a cue is not a simple matter of stimulus-response.  There is a lot that affects how quickly a motor response is expressed when any animal hears, sees, or feels something — which is to say that how quickly a horse moves a foot in response to the touch of a heel or rein is not a simple matter of picking the “one right part” of the step cycle to offer the cue (stimulus).

Researchers in RT want to know how quickly a human being can respond to switch off power to an engine if an alarm sounds, for instance, so most of the work on Reaction Time is on human beings. If you wade through those abstracts, you will see that their work suggests that a person’s reaction time can vary according to things like practice, the kind of stimulus presented, how many response options exist (in other words, do you have to decide whether to flip the lever or push the button, or is there only one choice), the nature of the on-going task or activity, and how much attention is being paid to specific parts of the environment.  Just to show you how important these factors are, visualize for a moment the memory of an experience I’m sure you’ve had — a sudden loud noise or sharp motion startles a horse, which proceeds to leap straight up into the air with all four feet at once.  It might have had all its feet on the ground a split second before, but the nature of these other factors changed its “normal” Reaction Time dramatically.

Most of us hope we don’t generate that kind of reaction in our horses.  The point is that when we talk about “when our horse can move a foot in response to our cue,” we are actually talking about Reaction Time whether we realize it or not.  And, given that we are, it’s a much more complex phenomenon than we imagine.  A lot of things, including training, can impact how quickly our horse responds to a stimulus-cue.  Furthermore, even though the Reaction Time for a foot placed squarely on the ground may be longer than if it was in the air when we cue it, that Reaction Time still exists.  A foot that is on the ground when we cue it can and will (if the horse chooses) react to our cue when it come up off the ground a few seconds later.

In the worst case scenario, the horse might react to the cue with a different foot and get a bit tangled up, which is how it’s said that cross-leading can happen by accident, or the delay of responding with the correct foot might lead to a bit of ungainly movement.  But most of us who ask at the “wrong” or “sub-optimal” time don’t usually wind up with our horses tripping all over themselves.  Usually what we get is movement in the direction we want, just a bit later than we asked for it — which is actually usually ok with us.  Few of us are engaged in activities that require our horse to move a particular foot at a particular time in order to, say, keep from falling into a hole in the ground.  So a little-bit-late response is just fine.

Or at least, this is what I thought until I saw a Tom Dorrance video about learning to move a horse’s feet individually while riding it.  In this particular video, Tom Dorrance worked with some riders and their horses and a pattern of tires laid on the ground, to help the humans figure out how to tell where the horse’s feet were at all times and respond to their horse and the tires.  The point of the exercise was to develop feel.  The demonstration of feel was that the rider could move a horse’s foot exactly and precisely at the time desired, to the place desired.  So there was discussion in the video about feeling when the foot came up off the ground and giving the cue then, as is standard in this type of training.  The result was astounding and unexpected.  Remember, I was pretty jaundiced about the idea that a cue has to be tied so closely to the step cycle because I had a healthy respect for the complexity of Reaction Time.  But every rider who engaged in this exercise, and learned how to feel where the feet were and to cue them at the “appropriate” times developed an incredibly light and responsive riding relationship to the horse s/he was on.

Jo uses some of Tom Dorrance’s methods when she gives riding instruction, and she’s the one who developed the closed-eyes on a bareback horse walking exercise I described in my previous post.  Sure enough, she found — and I saw it was so — that when people learned to feel their horse’s feet coming up off the ground and paid attention to it enough to cue them “at the right time,” they got light and responsive movement from the horse.  I also saw other trainers working on teaching the same “learn to feel when the foot comes up and cue it then” method in clinics in a variety of riding disciplines, and again I saw that when riders began to develop feel of their horse’s foot positions, a light and responsive relationship blossomed into existence.  The uniformity of this response shocked and amazed me, especially given the huge variation in different trainers’ means of explaining and teaching the concept.  But as long as the rider finally learned to feel the horse’s feet, the response materialized.  So clearly something important was going on.  But what?

Remember that we know Reaction Time is not solely or even primarily dependent on the timing of the stimulus or cue, but instead a complex phenomenon.  So we have an “effect” here, which is a light and responsive horse, the “cause” of which cannot be, biologically, simply applying the stimulus at precisely the right time.  To find the actual cause, we must consider what else all these experiences have in common.  And what they have in common is this:  the human learns to feel where the horse’s feet are all the time, and learns it so well that a cue can be offered at one particular point in the step cycle of one particular leg.  Notice which words are in bold and italics.  It’s about what the human learns.

A human who learns to feel where his or her horse’s feet are is thinking about, and even physically connected with, the horse.  That human’s mind is no longer inside their own ego and their own intention — at least for a while.  Instead, they are focusing on the horse.  They are feeling the horse, quite literally.  And Jo and I both suspect, very deeply, that what happens is that this change in focus and concentration allows the horse and rider to communicate simply and effectively in an entirely different way than the one we usually think of as “stimulus-response.”  Which means, of course, that Reaction Time is irrelevant.  What matters is simply the development of feel.  And an exercise in which you learn where your horse’s feet are — with such precision that you can cue one at one particular place in the step cycle — will teach you that.  But the exercise is not about cuing the horse.  It’s about teaching the human to feel.

If you read Tom Dorrance, Bill Dorrance, or Ray Hunt you will see that this is pretty darned close to the way they talk about “feel”.  And given that they coined the concept, at least in contemporary equine society, that’s enough for me to take it as a “good fit” to the only explanation I can see for what happens in these riding exercise — given that the neurobiological “reason” usually given (Reaction Time) is actually not valid.  Did Tom Dorrance know this when he used a line of tires to teach a rider how to tell where his horse’s feet were, and how to move each foot at just the right time?  Was he actually and simply trying to teach “feel” in a reliable way?  Yes, I think he was.

In my walking blog, when I suggested ways a person could develop feel of their horse’s walking foot positions, my thought was that I’d give lip service to the “reason” this is usually said to be a good thing to do:  Reaction Time, or “you can’t move a foot that’s not off the ground.”  It was, after all, good enough for Tom Dorrance in that clinic I saw in a video.  But my real thought was that anyone who did that exercise would develop proprioceptive awareness of the horse they were sitting on.  And I do believe, after all I’ve seen and after the training work Jo has done to explore this, that if you do this exercise you will develop your sense of “feel” and, as a result, start to develop a relationship of light responsiveness between you and your horse.

If it works better for you to skip all the talk about “feel” and use the short-cut of thinking that you can’t move a foot that’s on the ground, that’s fine.  You will still learn where your horse’s feet are and when to cue a foot to move.  And that will get you light and responsive movement from your horse.  But you’ll need to pretend you don’t know about the complexities of Reaction Time if you do that — which is ok by me.  The complexities of the natural world get abridged in common understanding all the time, largely for the reason of generating actions that have simple and predictable outcomes that seem to be based in science.  But, as is usually the case in all such situations, understanding the science a little better actually takes you to a place you might not expect to wind up.

So if your horse already knows how to “go” and all you have to do is relax the reins, you’re in good shape in lots of ways.  But an exercise that teaches you to feel where your horse’s feet are, well enough that you can cue one foot at one particular place in the step cycle, will still give you something new that’s worth developing:  feel.  Horses already know how to walk, after all.  It’s we humans who have to learn how to go along for the ride without messing them up.


This post was a featured blog entry on BarnMice, Nov. 22, 2012.


Learning How Horses Walk

Sometimes the best way to understand how your horse moves is to mindfully experience how your own body moves.  This is called experiential learning.  When I used to teach comparative anatomy and functional anatomy in the university, I always told my students that the number one tool we all have to understand how animals move is our own bodies.  See if you don’t discover something really cool about horse movement by trying this exercise in experiential learning.

What you need to do is read the next four paragraphs (down to the break in the text), and then set your computer aside and get down on the floor on your hands and knees.  Yes, really.  Don’t just think about it, and don’t ask someone else (like your teenager) to do it so you can watch them.  You need to experience this for it to have the substantial learning impact it can have.

Get on your hands and knees, supporting yourself.  In other words, you don’t want to crawl like you’re scooting under barbed wire.  War games are next week.  (OK, not really.  But don’t scoot.)  Then just crawl across the floor as far as you can without hitting the furniture.  Don’t think about it;  just do it.

Once you’ve done that, and have your rhythm established, turn around and go back the other way, still crawling, but this time just pay attention to — but do not try to control — the order in which your hands and knees hit the floor.  I suggest you choose your left knee to start with as you make mental notes, and that you then notice what hits the floor next after your left knee, then next after that, and so on.  Do it several times so that you have a good idea of the pattern that exists when you crawl.  You can even stop and jot that pattern down.

Now go crawl.  :-)  I will skip some lines here so you can’t easily see what I write next, and can instead scroll down to it after you do the crawling exercise.







Unless something really interesting has happened (and bodies are interesting things, that surprise us sometimes), your order of motion was left knee, then left hand, then right knee, then right hand.  Of course, if you started by paying attention to the right hand coming down first, then the sequence would be right hand, left knee, left hand, right knee, right hand, and so on.  But the sequence is still identical.  It is that you put down the back “leg” (knee) on one side, and this is followed by putting down the front “leg” (hand) of that same side, and then you put down the back leg of the other side, which is then followed by the front leg of that other side.

Note:  It is very important to realize that the sequence is always the same, but that it will at first look different if you “start” with a different foot.  Each time a front foot comes down and hits the ground, the next foot that comes forward will be the hind foot of the opposite side.  But this is then followed by the forefoot on the same side.

Here’s what it looks like in a walking horse, in slow motion.  These images are stills edited from a video by British videographer “Mike Snail”, who posts his work series at Youtube under “Slow Motion Connection.”  I left in the time stamp information so you can see the sequence of things.


Starting with the left hind foot touching the ground…





Then the left front foot touches the ground…





Then the right hind comes forward and strikes the ground…





And finally the right front foot strikes the ground.




The entire clip is at youtube, here.  I strongly urge you to watch it, paying close attention to the sequence in which the feet strike the ground.

Now of course the point of all this is to go back and compare the horse’s sequence of limb movements at the walk to your own sequence of limb movements at a crawl.  They are identical:  left rear to left fore to right rear to right fore.  And they are identical to crawling in a human baby as well.  It is thought that this similarity is due to neurological homology — that the firing mechanisms that activate the limb muscles in that particular pattern are literally the same in both horses and humans.  In fact, Susan Patrick and two other researchers published a paper in the Journal of Neurophysiology in 2008 suggesting the structural/ functional pattern of the nerves that activate crawling and walking is so conservative that it’s the same in almost all quadrupeds — which is to say, in every animal with four legs.  (Note:  In biology, “conservative” means it has not changed evolutionarily.  It has remained the same over vast spans of time during which other structures have evolved and changed.  For more discussion of homology in gaits, see the previous blog post.)

What does this mean for you, as a horseperson who wants a better experience with your horse?  It means you have an inborn mechanism that allows you to understand where your horse’s feet are.  You have probably been told by at least one trainer, on a DVD if nothing else, how important it is to know where your horse’s feet are as it moves.  (That’s because it’s only really possible to move a foot with rein or seat if that foot is off the ground at the time, not supporting the horse’s weight.  You can’t move a foot someone is standing on.)  And if so, you’ve probably also been told one or more complicated ways to learn how to tell where your horse’s feet are.  But, as long as you’re willing to use your experiential knowledge, you’ve got all the tools you need right inside your own body.

Here’s a suggestion:  crawl around some more.  Get a good “feel” for your own body.  (Yes, I am suggesting that good “feel” for your horse begins with good “feel” of yourself.)  Then go out to your horse and ask someone to hold its lead line for you, and just halter it.  Then do one of two things: (1) get on your horse with its normal saddle, but place your hands on the withers right in front of the saddle, as far down the slope as you can in that position, or (better yet!) (2) get up on your horse bareback and lay your hands on the withers on each side, on the sloping area.  Remember that if a friend is holding your horse’s lead line, you don’t need to worry about holding the reins. Then close your eyes and pause, for a moment, to remember — as viscerally as you can — how it felt to crawl.  Fix that in your mind.  You can even let your legs and arms twitch a little bit as you remember their motion.

Then have your friend slowly lead your horse forward at a walk.

What you want to do here is focus on the similarity between the four feet your horse is moving and the pattern of your own limb motion when you crawled.  If you can let those two “walking feelings” overlap in your mind and in your body-awareness, you will suddenly have very strong “feel” for your horse’s feet.  And although at first you will be focused on when each foot hits the ground, the awareness will grow to the point that if you just turn your mind a little bit, you will know when each foot comes up off the ground to swing forward.

If it helps, particularly if you are on your horse bareback, you can lean forward so that you are oriented with your back more parallel to your horse’s back when you do this, which will overlap your fore and hind limbs more completely with your horse’s fore and hind limbs.

Either way, with a saddle or without, this exercise allows you to use your own body’s proprioceptive senses to feel your horse.  Your horse, in other words, becomes an extension of your own body.

And how cool is that?

Many thanks to my business partner Jo Belasco for the work she’s done with bareback riders who have their eyes closed as they learn to feel a horse’s feet at a walk.


This post was a featured blog entry on BarnMice, Nov. 19, 2012.


Gaits in Horses and Humans

In a very interesting conversation with a trainer whose observations are consistently brilliant, I realized that it’s hard for riders to see the similarities between human and horse gaits.  This is because the vertical position of a human’s torso, due to our being bipedal, changes the orientation of the arms or forelimbs, thereby obscuring their motion.  So I thought it might be useful and interesting to compare the motions of humans and horses, anatomically.

First, here is a horse in a trot.  If you ride, you are familiar with this gait in which the legs on one side of the body either come together beneath the midline at the same time or extend away from the midline at the same time.  In this case, the left fore limb is pulled behind its neutral position, and the left hind limb is moved forward or ahead of its neutral position. The neutral position of the uppermost limb bones is important to understand in this case.  So let’s look at a horse skeleton very quickly, to see what’s happening to make the limbs look this way.

In this horse skeleton, the animal is simply standing, not moving.  So the limbs are said to be in a neutral position because the horse isn’t going anywhere right now.  I have colored two bones red.  The one in the fore limb is called the humerus.  It articulates with the scapula at the top — and you know the scapula because it underlies the withers.  At the bottom, the humerus forms part of the horse’s elbow, just in front of where you put the cinch or girth.  Most of the humerus bone is not easy to see when you look at a horse, because it is so closely bound into the chest that we just don’t notice it.  But it’s there, and you can see its approximate position marked by a red line in the diagram of the trotting horse, below, that I have modified to show you where these crucial bones are.

I have also drawn a little turquoise arrow to show you the direction the humerus has moved (from the neutral position) to get to where you see it, in this photo of the trotting horse.  You may wonder, “If that’s where it is when it’s pulled backwards, how far forward does it go?”  You can tell by looking closely at the front of the horse in the picture.  You can see where its left elbow is;  now look at its right forelimb and imagine about where the right elbow is.  That elbow is a lot farther forward, and it’s because the humerus of the right leg is oriented about as far forward of its neutral position as it can get.  Horse humerus bones are not able to reach out as far as human humerus bones can.  But they do move, and you can see how much by comparing the positions of the two elbows on this horse.

Now let’s look at the back leg, comparing it to the skeleton above just as we did with the front leg.  Remember there is a bone colored red on the back leg as well, and that’s the femur.  I have marked the position of the femur with a red line in the trotting horse diagram, too, and also put in a small turquoise arrow to show you the direction it has moved (from the neutral or standing position) to get to where it is now.  If you look at the skeleton one more time, with the legs straight down as the horse is simply standing, you can see that the fore limb has moved behind that position, and the hind limb has moved ahead of that position.

So take a moment to familiarize yourself with the positions of the horse’s upper limb bones in a trot, and then let’s look at a human being jogging.

Here is a photograph of a jogging human being.  To many people, this does not look like the trot in the horse that we just saw.  But that’s only because your eye is tricked by the human’s vertical torso.  Imagine the person standing in a neutral position, not going anywhere.  The legs would be straight under the body, and the arms would be hanging straight down.  Now look at the left arm and leg, facing the camera.  Where is the left arm, with respect to the neutral position?  It’s behind it.  It has been drawn backwards.  And where is the left leg, with respect to the neutral position?  It is in front of it. It has been drawn forwards.  Does this remind you of anything we just saw?

Here is the same image, drawn and labeled as I did the trotting horse.  Compare the two labeled images, particularly the motion arrows of the humerus and femur bones in the human and the horse.  This still might look to you like it’s not the same thing, in which case it might help to turn the woman in the picture so that her torso is level, like the horse’s torso is, and then put her arms and legs back in place.  I cut the picture up and put it back together to help you see what this might look like, and it’s below — with my apologies for the rather Frankenstein’s monster effect of the cutting-and-pasting!

Her right arm, away from the camera, looks a bit disconnected here because of course it would be more visible if she wasn’t standing upright.  (When she is upright, her right humerus is partially hidden by her chest.)  But pay particular attention here to her left arm and her left leg.  The humerus of her left arm is drawn back, and the femur of her left leg is forward.  This is exactly the positions we see in the left limbs of the trotting horse in the first picture I posted on this blog.  And that is no coincidence.

Humans “trot” when they jog or run.  This is not metaphor, but actual homology.  Homology is an anatomical term meaning that something is similar because of an underlying commonality.  In this case, there are structures that are the same in both horses and humans — the humerus bone and the femur bone, for instance.  (Both articulate to the same bones at both ends, in both animals, and both are derived from the same types of embryonic tissues.)  The muscles are largely the same as well, and these are the muscles that move the humerus backwards and forwards, or move the femur backwards and forwards.  But, even more importantly when it comes to discussion of gaits, there are neurological commonalities as well.

Muscles contract to move bones when they are stimulated by nerve impulses sent by the brain.  Different patterns of limb movement that are highly stylized and predictable — like the trot — are created by very specific patterns of nerve firings on both sides of the front and hind limbs.  These firings must be coordinated very precisely for the animal to move properly without losing its balance.  For instance, simply to move the humerus backwards requires that a number of muscles fire in a very specific sequence and also that a number of arm muscles do not fire at all!  When you think about this having to happen on all four limbs simultaneously, you can begin to get an idea of the complexity and precision of neural firing patterns that generate movement in a certain gait.  Neural firing patterns — the actual placement of the nerves as well as the systems that regulate the patterns of firing in the brain — are very conservative, meaning they are much more similar between different animals than we might think they would be.  So even though a horse and a human look very different to our eyes, they both have a humerus bone and a femur bone — and the pattern of neural firing that produces a trot is not just similar, it’s nearly identical!

In my next post, I will talk about the walking gait in horses and humans.

(Note:  If you wonder why the woman’s lower forearm and hand are drawn up so close to her body rather than being extended on back and down as in the horse, it’s because she is not putting weight on her hand as she runs, as the horse must do.  Joggers are commonly taught to flex their elbows and “tuck” their forearms and hands close to their bodies to reduce drag and make running more efficient.  One reason we pay such close attention to the humerus and femur to understand gait is that they are under the closest neurological control and so show us the pattern most clearly.  Runners who try to run without at least letting their humeri swing as shown here generally find they cannot do much more than hobble — because the neural firing pattern is so tight that the femur needs the humerus to move in a trot in order for it to move in a trot;  the two are literally connected by the neural firing patternA person can learn to move only the femur bones to jog, but the firing patterns of the nerves are demonstrably very, very different — and not the “normal” pattern typical of a trot, even in the muscles around the femur.  This is why so much physical therapy is necessary to help people re-learn how to move if they suffer injuries that interfere with the normal firing patterns in any way.)


This post was a featured blog entry on BarnMice, Nov. 11, 2012.