Skeletal variation — the impossible dream

22 April 2007

I’ve been taking a yoga teacher-training course, and I just finished a fascinating anatomy workshop. One of those classes where you slowly come to realize that everything you thought you knew about a topic (yoga poses, and Pilates) was wrong…

Though by the end of the workshop that got modified to “incomplete”.

The instructor started by talking about skeletal variation. If you’d asked me beforehand I’d have expected there to be variation (that’s what evolution is all about after all), but I would not have expected it to be very significant (again, evolution would have culled all the extremes of variation.)


He showed us a slide show (I recommend looking at it, it’s on-line, though in a slightly different order). Pictures of bones from a museum collection. The first slide showed two femur heads — the angle of inclination, the length of the head, and the size of the top of the femur were quite different. Because of that, the difference in range of motion (for abduction) is going to be large.

He said he only looked at about 30 bones to get that difference.

Then a view of femur bones lined up side by side showing differences in the twist inside the femur (so that for some people the knees will point straight up when the femur head is seated normally in its socket, and in others they will point in).

Then similar twists in the tibia (determining how the toes will point when the knees are up).

Then vertebrae showing why some people’s spines would bend backward more easily than others — there’s just more room between the spinous processes.

And so on.

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Our culture believes in perfectibility, that if we work hard enough we can achieve perfection (and if we don’t achieve it then it’s our own fault and we should be ashamed of ourselves). We’ve been saddled with the impossible dream of perfection. The perfect body. Sadly even yoga isn’t free of this.

I’ve been taught, in both yoga and Pilates, that the restrictions to my ability to do the poses are from muscle tension (or tension in the fascia). Both of these can be reduced by stretching — admittedly it can take a long time, and if I do a lot of running the best I can hope for may be that I do not regress — but these can change, and I can reach perfection.

My skeleton will not change.

Paul claims that for most of us in that class, at most joints, we are up against our skeletal limits, not against muscle/fascial tension.

And we can’t change our skeletal limits. No matter how hard we try we can’t stretch out any further. We can’t improve our poses where the bones restrict us.

(Now he’s not saying we should just give up and not do the poses any more, we need to keep doing them to keep the body supple (and all sorts of other reasons, but this was an anatomy class and he was giving anatomy reasons), but no matter how much I struggle I’ll never get a better wheel (backbend) — unless I dislocate my shoulder or break my back. He also says that we should strive energetically beyond what is possible — but not expect to achieve it.)

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After looking at dead bones we turned to our own, live ones. We analyzed each other. He showed us simple moves that put one joint through its range of motion in one direction. If muscle tension is the limiting factor then we’d feel sensation on the side of the joint that is opening — where the muscle is stretched, but if it’s compression from bone hitting bone we’d either feel nothing (just the end of the range of motion) or sensation on the side the joint that is closing.

I only once felt muscle tension. My adductors are tight. (Hamstrings too, but we didn’t test that).

He would go around the class and watch us and pick several samples (the extremes) and show us just how different we were.

There were 20 of us, yet our variation was large.

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My neck doesn’t extend very far back. I was one of the extremes (with very little range of motion) for this test. I could only extend back about 45°. The other extreme could bend her neck back 135°. This means that I just will never do certain poses well that require neck extension.

(I mentioned this to a yoga friend, her immediate response was, “You’ll just have to stretch it out.” The concept of perfectibility and the need to achieve perfection is deeply rooted)

One of his examples was the Pilate’s seated roll-up. We all get taught “Pick your vertebrae off the floor one by one” and that “once you learn how to do that the pose is easy”. Well we can’t. In everyone (or anyway everyone in our class, and everyone the instructor had seen) the lower back just will not flex and comes up in a clump. But even the thorax is limited. One woman could barely get her shoulders off the floor (and I don’t mean the base of the blades, I mean the tops), while another could roll up at least to T12. It’s not that Kelley’s abs were weak, it’s just that her thorax would not flex. Her ribs were fixed and would not let that motion happen.

The most interesting motion was raising the arm. I’d never realized this, but raising the arms up (flexing, starting with arms at the sides and raising them parallel in front of the body and going up overhead and then beyond — if possible) is actually the motion of two joints. First the humerus rotates in its socket until it hits the acromium process of the scapula, then that rotates the scapula down and the clavicle up and in toward the ribs. Eventually the clavicle will bump against a rib (or some other bone) and stop.

He had us pair up and clamp the acromium process on our partner so it would not rotate. I had one of the better rotations of the humerus. Then we allowed the acromium process freedom to move to see how far up and back the arm would go. The woman with the worst range of humoral motion could get her arm higher than I. My clavicle barely moved. I’ll never be able to get my hands behind my ears, my bones won’t let me.

I’ll never be able to do the full range of motion my Pilates instructor wants to see me do with arms overhead. No mater how long I try to stretch my muscles, they won’t.

I’ll never be able to improve my wheel, I just can’t flex my arm far enough back to get a good angle. I can’t extend my lumbar spine enough.

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And it’s not just range of motion that matters. Proportion also matters. In headstand with the forearms on the ground (not tripod headstand with the hands on the ground) the length of the head+neck compared to the length of the upper arms is critical. If the head+neck is taller than the upper arms then the cervical spine will be crushed (if the pose can be attained at all); on the other hand if the head does not touch the ground at all then all the weight will be carried by the forearms and they will soon tire.

The shape of the bones even when not at the joints can matter. He had us curl up into little balls and hug our knees tightly to the chest, rounding the back. This was extremely painful to one person. Her iliopsoas tendon got pinched between the pelvis and the leg. A pose which I’d always thought of as relaxing was torture for her.

Changes in one part of the body have unexpected effects elsewhere. He had us get into straddle-splits (seated with legs as wide apart as they go) and then fold forward. Now some people’s toes point up, some turn inward and some turn out. I’ve been taught that the “proper” way to do the pose is to have the feet oriented with the toes straight up. He went around and rotated people’s feet up. Magically the torso would rise (in some cases). Rotating the feet is actually a rotation of the femur in the hip, and this may rotate the pelvis (depending on the structure of the hip joint) which causes the torso to rise. What I’ve been taught as the “right” way to do the pose actually reduces its effect on some people.

I was taught that before going up into shoulder-stand I should clasp my hands behind my back and wriggle my shoulder-blades together so that my neck lifted off the ground and the weight of my body was supported on the back of my head and my shoulder-blades — this protects the neck. But some people can’t clasp their hands behind their backs (the bones of their scapula get in the way), and attempting to contort their bodies to do so will actually press their necks more deeply into the ground. In other words, something which protects most people will injure others.

Lest it seem that all variation is between individuals let me mention my own legs. If I sit with my legs straight out in front of me and my knees pointing up then my left toes also point up while my right toes point off at about 10° to vertical. My left tibia is straight; my right tibia is spiraled out. This asymmetry has been my bane for the last five years or so (since I started running again), and I’ve kept trying to find some way to train my muscles to pull it back into alignment. But I can’t. It’s in the bone. Either the foot is off or the knee is, and it’s much safer for the foot to be misaligned than the knee.

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I’ve been studying Iyangar yoga, a system of yoga which is very precise about alignment. BUT it makes the assumptions that all bodies are the same — or will be the same once the muscles have been stretched. The instructions for each pose are the same for everyone and we all strive for the same result.

But I’ll never be able to squat, legs together, flat-footed on the floor. My tallus bumps into my tibia. There’s no muscle to stretch. The only thing I could do would be to become flat footed, if the arch of the foot collapses then the tallus will rotate forward allowing a different range of motion.

I’ll never be able to do Warrior 1 “right”. Again my ankle won’t allow my rear foot to stay on the ground without rotating my pelvis back on one side — and that’s wrong too. I’ll never be able to raise my arms behind my ears.

I’ll never be about to get my right knee and my right toes to point straight up at the same time. Despite what my instructor says, I will never be able to use my muscles to twist my tibia into the “correct” orientation.

My skeleton isn’t abnormal. At most joint/motion combinations I had normal range of motion. At two I was the low extreme and at one the high. That was true of most of us. No one in the class was extremely inflexible; on the contrary, because we’re all reasonable good yoga practitioners we are probably more flexible that most.

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From the Pilates classes I’ve taken I get the same impression, that there is a perfect alignment which we all can attain if we just stretch those muscles enough. If I can’t raise my arms over my head it’s because I’ve got tight shoulders and if I stretch enough eventually some muscle will loosen enough to give my arms freedom. But it never will. There is no tight muscle. There is just bone hitting bone, and nothing short of injury will change that.

So we went through most of the major joints (didn’t bother with the toes or the digits, but most joints) and we saw a wide range of possibilities in what our skeletons allowed us to do.

Then the instructor took a step back. We’ve all been practicing for years. We’re all athletic. Most people who come into a yoga studio for an introductory yoga class (remember, we’re training to be teachers) will have really tight muscles. For most of them, not all, but most, their restrictions will be from muscle tension not from bone on bone compression. For them, most of what I’ve learned is reasonable in the past. For the first year or two it is true to say “Just keep stretching and eventually you’ll get closer” — not that they will necessarily achieve the pose, but they’ll almost certainly get closer to it.

The style of teaching precisely can be useful. It has evolved because, in most cases it prevents injury. It is still a useful tool — for the novice. But as someone advances they are more likely to hit their own limits, more likely to injure themselves trying to achieve the “perfect” (but for them impossible) pose, more likely to need to modify the pose to suit their own bodies.

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At the moment I feel that I have no idea how I want to proceed in my own practice. I’m going to put far less emphasis on getting alignment right, because I no longer believe that that is possible or even very meaningful.

I’m somewhat at a loss as to what I can teach…

I’ll be interested to see how (if) things change, or if I’ll just drop back into old habits.

I hope not.

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Now… why am I posting this on my running blog? Well, it interests me, but more importantly I think I now understand why I’ve been having so many problems with my right knee and hip. I’m just warped.


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