In my book about feet I also talk about bone. I also talk about a lot of other things, but because a big giant high heeled shoe is on the cover, it’s probably always going to be associated with feet instead of whole-body alignment, but that’s OK, because there are a lot of people out there with sore feet.
Anyways.
There is a section in Chapter 3 on why this body position (on the left) is less weight bearing that the picture on the right.
If you’re kind of intuitive in how things “feel” then you might be, oh, right. That makes sense, I can tell the difference. But if you like a little more meat to your theory, when thinking about it, you might be like, Hey! That doesn’t make sense at all. Because I learned that “weight” is just our mass accelerated by gravity. So if my mass is the same and gravity is the same, how could one body position be more or less weight bearing than another?
So, allow me to explain, keeping in mind that I’m going to do a crappy job because I’m going to do it without using a bunch of science-y terms and no equations. So if you’re a theoretical physicist reading this, give me a tiny break. This is a blog about human body parts, and I’m doing the best I can.
Once upon a time “weight” meant mass (how much stuff that makes you up) accelerated by gravity. But when it came time to actually use this theoretical concept, it turned out that where an object was relative to something else was important. Mathematically this is like ?!HUH?!? but biologically it might make more sense: If you are falling out of an airplane your “weight” is about the same as when you are standing on the ground. But these situations “feel” different to the body. And I don’t mean that falling out of an airplane makes you want to vomit or scream or whatever. I mean the way your body interprets (feels or experiences) your weight depends on whether or not something is underneath your feet.
Or if you imagine a single bone – the way a bone experiences its weight depends on whether it is moving through space, not touching anything or if it is pressing up against something. Once the sciences moved from the more theoretical to the more applied, the term weight and force due to gravity became too ambiguous and confusing for use. So, the definition of weight as we use it today (i.e. I’m going to go weigh myself on this scale) is really defined as the effect of what is theoretically known as weight — also called the “contact reaction-force against the force of gravity.” This is why we measure our weight on scales — to determine how much your mass is squishing something. The amount of squish determines your weight — not the other way around. Which is why mathematics often seems obtuse. Which is a geometry joke. Which I hope you got.
Also, this means that weight is really a relationship between a scale and the mass that sits just on top of it. Note: If you’re thinking that you’re going to start weighing yourself in the morning, leaning your torso 24 inches out in front of your feet to get a lower scale reading know that 1) most bathroom scales are designed to negate this effect and 2) your actual mass, how you look in your jeans, and your metabolism will not be affected in the slightest. But you can go ahead and try it if you’d like.
Possible Reader Question At This Point: This post is boring. Why should I read it any further?
When it comes to bone health, you’ll want to keep in mind that how much “weight” your bones experience is calculated based on how much mass is stacked directly above whatever is doing the weighing — in this case the mechanoreceptors in a particular area. Which is why alignment (that is the position of every part relative to another) is so important. This orientation of parts determines how every other part is loaded.
In my book I define weight-bearing as: when a structure is carrying the full burden of its mass; in the human case, when the bones are holding the vertical mass of the body.
The term “vertical” is an important piece of understanding the weight/weight-bearing/bone generation process.
This is a bone:
I know it looks like a chicken bone, but pretend it looks like a femur or something. Although, chicken bones work in the same way, so, go ahead and just accept that it’s a chicken bone and that I’m a terrible drawer.
This bone has a center of mass — that is, a point at which you could balance it on your finger. Or head.
As long as this bone’s center of mass aligns with the center of the scale (aka vertically stacked) the weight of a bone equals its theoretical weight (mass times acceleration due to gravity). Or, said another way, if you put the chicken/femur bone on a scale like this:
It weighs “W”.
But if you put the bone on a scale like this, where the center of its mass is off to the side of vertical (keeping in mind that bone three dimensional, so this can be off in any direction from vertical) the scale will read a weight that is LESS than its theoretical weight or, less than the weight it had when its center of mass was stacked vertically.
Why? Because a scale can only be compressed, and hence measure, what is directly on top of it. The part of the bone NOT on the scale is essentially in free-fall and not contributing to the weight measure on the scale. Don’t get me wrong. The falling bone parts (now creating torque instead of weight) still need need to be dealt with to keep you from falling over — but now your muscles and connective tissues must work more than they should to create these tensions and your bone is working less. Which means 1) more soft tissue damage and 2) less bone density where you need it. This is what compensating is all about. If your desired end-result is simply not falling over, it doesn’t matter how you stand and move. But if your desired end-result is maintaining long term function of tissues, how you stand and move matters more than anything else.
I’ll also have to mention that the size of the scale is important. While weighing yourself in the bathroom might seem like a huge deal biologically (or is that psychologically?), it’s not as important nor is it always equal to the weight you put on your bones. Your bones are filled with small scales called mechanoreceptors. It is the regular compression of these cells that send the “GO BUILD US SOME FRESH BONE, WE’VE GOT WEIGHT TO SUPPORT!” signal. These scales determine how much bone to build in that specific area, based on the weight signals they receive. Which is why “weight-bearing” status is so important to the bones. The less weight you bear, the lesser the density to the bone.
Every bone has its own set of scales because each bone has a unique responsibility of staying strong enough to hold what is (or should be) directly above it. It is the stimulation of these tiny, inside-the-bone scales that not only determines bone density, but earlier on, the shape of the bone itself as well as later-developed pathologies like bone spurs.
Going back to these pictures:
Consider a small scale in the neck of the femur — aka the most common place for bones to decrease in mass, becoming too weak to hold up the weight of the torso.
The scale in the hip seen in the photo on the right will receive a greater weight signal from the torso, stimulating it to build more bone than in the hip in the left photo. This also goes for standing with your legs wider or more narrow that what vertically aligns the femurs center of mass as evaluated from the front:
In non-vertical standing habits as well as exercise modalities that use the skeleton in ways that do not offer weight-bearing loads to the bones, the result will be various bones lowering their densities and weight-bearing abilities accordingly. Your bones are not genetically programmed to be a certain density. Rather they are responding to the loads you create and shaping and filling themselves according to how. you. move.
This post would not be complete without mentioning that bone also responds to tensile loads, which are places where the bone is being pulled on by muscle or ligament attachments. When you habitually stand in a non-vertical way, for example, you create very little weight on the bones (especially the hips and lumbar vertebrae) and instead, convert your weight into an excessive tensile load on the lower leg bones (as well as creating tissue tensions and damage all throughout the body) — which will result in a decrease in vertebrae and hip bone density and often times an increase in the densities of the lower leg bones.
Hey, great! If I take my hip density away but increase it in the lower leg, that’s good right?
While that seems logical, alas, it is not correct. Bone density, as a total number, is not important. What is important is the function of bone density. Having greater bone densities in your lower leg will not help your hip hold you up or keep your vertebrae from collapsing when exposed to dynamic movements of your torso. So when you check out studies that say “bone density increased from doing this” you want to read carefully about specific locations before and after and then compare those results to areas that of bone mass that are important as far as health research goes (hips, vertebrae, ribs, and wrists).
What’s this all have to do with you? What is the “takeaway” information?
1. In the search for the “best” exercise prescription for bone density (as well as for all of the weight-sensitive mechanoreceptors) HOW your body is oriented while moving is just as important, if not more, than WHAT you do to move. Consider your alignment and your weight-bearing status when you choose.
2. A load is not a load and a force is not a force. “Balancing” out body parts — that is keeping it upright by shifting a little here or there — should not be the end goal. Restoring the forces in the body to where they are stimulating what they should be and not stimulating what they shouldn’t is the way to get to the finer elements that make or break disease.
Suggested T-Shirt phrases for Alignerds:
If there is no scale, there is no weight.
or how about, Wanna lose weight? Thrust your pelvis and lift your ribs. Results guaranteed.
{Oh, and if you’re interested in taking the first step to better bones (or knees or hips or your back or whatever your whole-body issue), take a look at what your shoes are doing to you every day and start with these basic correctives! Download a free chapter on footwear and bones here: Click}
I want my t shirt to say “mechanical zero” or something along those lines.
How about mechanical hero? More fitting…
“Wanna lose weight? Thrust your pelvis and lift your ribs. Results guaranteed.”
Funny. I swear I saw an infomercial recently for a weight loss product that showed before and after pics…that DID JUST THAT! I swear! I had to pause and rewind it and show my husband! So, really that’s all you have to do. And you forgot to mention it flattens the belly too!
Word. Will talk to my agent.
Must get an agent.
Wow, this explains a LOT about the mild stenosis in my cervical spine. YIKES. And the massive tibia and hallux valgus on one side but not the other and and and. Too much out of alignment loading. But the question is, if we can load appropriately can issues such as spinal stenosis be remedied? Bone is generated as a result of loading, but can loading in a different way reverse the trend?
Alos, I want a T shirt that says:
Tune in to your body
Turn on your mine
Drop your ribs…
or
Are you REx-perienced?
I like those shirts. And yes, the nice thing about bone is that it is always remodeling based on the current load. Change the load and the bone responds — a phenomenon that is accelerated in space, which why astronauts lose so much bone mass so quickly. The tough part, as you know, is body-use habits are SO HARD TO CHANGE because the habits are so deeply etched in the mind. Slow changes are still affecting the tissue RIGHT NOW, so it’s just how it needs to be done!
Let’s open up a t-shirt shop…
This post is bone-a-fiedly super!
I want to be dense! Many thanks, o.
T-shirt: Density is my Destiny
I’m not clear on the posture you recommend; in the pictures, it seems like the butt is tucked under and the tummy is tucked in on the picture that shows the weight properly distributed over the femurs.
On the WholeWoman website, Christine talks about posture as the most important factor in pelvic organ health and even hip health – but her recommended posture seems to look more like the posture in the picture that you DON’T recommend.
Here’s a link to her page on how posture affects the hips:
http://www.wholewoman.com/newpages/savingyourhips/
In the FAQ, she describes the “Whole Woman Posture” in depth.
We don’t tuck the pelvic or engage the TvA — we use a neutral pelvis (read “Neutral Pelvis” for a better idea) which is as you mentioned, different that the WW alignment where they suggest a pelvis that is similarly oriented as it is in quadruped animals. We too would say that alignment is the most important factor in pelvic organ (and all other part-health as well) but we do not have the same alignment guidelines. I apologize — this must be confusing for someone to “find the answer!” I suggest reading through more posts to get a feel for the biomechanics of how the two ways differ!
You rock!
I love reading your posts (and I’ve “earmarked” your book to death). I’m nowhere near “right”, yet. But I’m making progress.
“Your bones are filled with small scales called mechanoreceptors. It is the regular compression of these cells that send the “GO BUILD US SOME FRESH BONE, WE’VE GOT WEIGHT TO SUPPORT!” signal.” – such an awesome LIGHTBULB for me! Thanks!
Great post, Katy!
I understand about standing with feet hip-width apart, but does that apply to walking too?
Yes, it applies even more to movement (i.e. walking) because bone responds to load cycles, so standing there “vertically” really won’t get you the bone that you need for supported movement! Enjoy playing with it!
Curious about the walking ……… In Esther Gokhale’s book “8 steps to a pain-free back” (& I will say that I am tired of 3, 5, 7, 8 10, 12 (you name it) steps to a better whatever …….) she does have some great pictures of people In Africa walking much more in a straight line ie as though the inside edges of feet were either side of a line as you walk. And the bare-foot running community seems to have found that running as though you were just either side of a line feels the best too. This does, in fact, feel right for me also. Walking with my feet apart feels very ‘clunky’, as though I have to shift my whole self from side to side instead of moving more ‘under my head, which (for me anyway) creates much more of a sense of gravity going directly through from my head to my feet. If you are shifting from side to side as you walk then the forces aren’t going thru as clearly ????? I will pose this to my Feldy community & see what their wisdom is ………. I know that I find walking to be a highly complex activity to analyze!! Thx!
You’d be surprised at how difficult it is to get a book published without promising something great with very little steps/time/changes to be made!!!
Toe-ing the line, as you mention, becomes less weight bearing the wider your pelvis is. Certain populations, races, genders have trends in pelvis width that would make this more or less of an issue — so it’s not a very good blanket alignment marker for everyone. One of the reasons it “feels better” is because when you have very little lateral hip strength, you can’t walk otherwise. In the same way that not doing the monkey bars is more comfortable than actually doing them
Doing more work, when your muscles have atrophied, will always feel less comfortable, unfortunately. Such is the process of adaptation. You can search “monster walk” to see more about appropriate levels of lateral hip strength. You really can’t just widen your stance (without lunging from side to side) until you’ve gradually strengthened your lateral hip muscles, so it is a process to widen. Also, an interesting research search to do is osteoporosis in runners (especially longer distances) — always keep in mind that what feels good doesn’t always imply what is more or less beneficial, biologically speaking.
Thx Katy. I also hate subtitles. Once you’ve read the subtitle you don’t need to buy the book. BUt then again you can save a lot of money.
Not-hanging from a pull-up bar feels much better than hanging too …… I do agree that our ‘debauched sense of kinaesthesia’, to quote Alexander teachers, makes it challenging to actually recognize what feels ‘good’ versus what feels ‘habitual & familiar’. Which is why we can’t really ‘just make changes’ until it makes sense to our brain, whatever the movement, organization, change …. however much we may want to ‘try & make it happen’.
Osteoporosis in runners …. I’d be willing to suggest that, if really proven, it’ll have something to do with heel landing, instead of forefoot landing …..
Hey Katy,
If wrists are an important area for bone density… what does that mean? I get that if your body is aligned and loaded over your legs, hips and spine, that that will increase their bone density. But can you talk about the wrists? They are just hanging there, without any force from the ground, or much of anything, I would think (for example, while walking). Wouldn’t that lead them to have lower bone density?
Yes, this is a hip-specific post. Ribs down and back aid with vertebrae. Wrists and ribs have to do with a bit more complex alignment issues (i.e. breathing and upper-body use.) The wrists need to be loaded more in general – i.e. coming up and down off the ground, hanging, using arms and shoulders for more than typing and driving
Since you’ve never walked on your hands (since crawling, anyhow), the amount of density there has never been based on your gait pattern but use in every day life. The tighter the neck, shoulders and the less you’ve used your arms, fingers — hung from trees, etc. — the lower it gets…
Thanks for this post Katy. This aligns a lot better with what I have in my mind. I am still not clear on how mechano-receptors work (really only in a vertical direction?) and how they make a difference between gravitational pull or loads through muscle pull. Will look this up when I am back home. Is the neck of the femur a problem site then, because it is never vertically aligned being at an angle at the top of the femur? Or are the mechano-receptors oriented in a different way there?
You are welcome! I’m glad it helped. To expand briefly, mechanoreceptors is a large term for a cell that gets a chemical process going. How they work is quite complicated (and not that well understood, frankly), but more importantly and probably more pertinently is that it’s not like one or two receptors, but a ton. And each of these is not just taking a load, but also measuring the vectors of the load and responding appropriately. “Correct” bone density is actually along various trajectories of use because we are such dynamic movers. We’ve simplified the measure of bone medically (as in high or low compared to the population), because that’s the only way to screen for health purposes. Micro-trajectories of density are too small to quantify, although in general they have been found to be similar to that of a crane (because the loads created by the body are due to medial mass when walking).
There isn’t a way, at least now, to create an instrument that is the size of a cell, implant it into a human, to see how a cell measures the difference between compression and tensile forces. Too difficult for even super-smart people (like engineers) to measure with super-fine instruments, all we’ve been able to measure is density in general and see that when it’s low, fractures arise.
So, short answer: Mechanoreceptors measure all loads, but will differentiate between the load and respond differently. What has been found (in larger embedded force plates) is that tensile loads never exceed 1000 ME (trying to write micro-epsilon) and compressive always exceeds 1000 ME, so not only is the direction always differ, but also the magnitude. End result: You can’t replace weight bearing with tension as you will never get an equivalent load nor trajectory of bone. (The trajectory aligns with the direction of pull, so a compressive load will never strengthen mass to resist tension and vice versa.
In regards to “why the femur”: Density is a relative value to yourself at some other time. The femoral neck isn’t a problem because it’s not vertical — there are many non-vertical bones that maintain density — it’s just that the vertical load over the neck is less than it should be (or more less than it once was, to be more correct…) As movement habits change throughout a lifetime, our whole-body vertically-aligned mass seems to be the most habitual change as a culture.
Wow. Another paradigm shift…I’ve been standing with my feet pelvis-width, but hadn’t applied that to my walking. Doh. Still, it would be impossible to change everything at once, right? Now I just have something new to work on
Thank you!
Quick question: As I’ve been standing with my weight over my heels and walking heel-toe, my heels have been aching. Is that because I’m increasing bone density, or because they’re just getting used to more work or is it likely that I’m doing something wrong?
Thanks again!
Tissue needs to adapt to new loads. I doubt you’re feeling the bones “generate” but you’re definitely creating a response in first the nerves, then the connective tissues, muscles. You can ease on and off until you feel like you’re stronger if that helps!
Hi Katy,
I have osteoporosis due to a history of anorexia and am wondering how this differs to osteoporosis caused by alignment issues. Surely a lack of nutrition and hormones are as much a cause as incorrect alignment (although alignment does become problematic anyway due to loss of muscle). I have also been led to believe that I will not be able to build any bone density until I reach a normal weight and that bone density peaks in the 30s after which it is downhill all the way. Is this true? Is it possible for me to rebuild my bones by improving my alignment?
Thank you for such a wonderful blog.
Regards
Sarah
HI Sarah,
Without knowing how old you are or the period of time in which you were dealing with anorexia, my comments: Your peak bone mass occurs about age 20. So if you were undernourished at that time, you could have set a low-cap to your bones that you won’t be able to top despite nutrition, movement, or chemical attempts now. You can, however, maintain your peak by 1) aligning your bones while walking and 2) maintaining adequate nutrition. There is no genetic “down hill” to bones, there just isn’t any uphill, if that makes sense. And, for sure, building back your weight will increase loading to the frame so it’s all essential, really. I wish you all the best of luck in all aspects of your road to better health.
Metta,
Katy