Bio-Tensegrity - A missing link in Biomechanics
27th October 2015
The way we have viewed animal movement in the western hemisphere, for the past few hundred years at least, has been based on the principles of mechanics. We thought of ourselves as a system of Columns, Pulleys and Levers because the only reference we had to similar qualities was through mechanical fabrication, like buildings, bridges or watches. A drawbridge seemed to act like the hinge joint of the Elbow, so it made sense at the time.
Actually, it made so much sense it wasn’t really questioned for a very long time. It is still common belief that our spinal column is indeed a column, that our Femur rests on top of our Tibia to form the knee, and our biceps brachii (and associated local muscles) is the only pulley in the system that flexes the Elbow. And we even have a name for it - Bio-Mechanics.
Bio = Greek for ‘Life’ - The study of Biological Organisms
Mechanics = The study of mechanical principals
Within Bio-Mechanics we look to discover the mechanical forces, angles and loads placed upon the joints of the human body, in order to understand how it copes with and achieves movement. The picture above is a page of the first works by Giovanni Alfonso Borelli, from the 17th century, who is regarded as the founder of Biomechanics. Since his early calculations, we now are able to explain in great detail the forces placed upon the body through these methods but it leaves one question unanswered.
If we are a stack of bones in a column, how do our joints have such free motion without a pin to support the axis of rotation? Even a hinge needs replacing once it has scrummed to the forces of friction.
Adding a New Paradigm - Bio-Tensegrity
Since Buckminster Fuller started sculpting tensegrity structures that could hold their shape - despite their orientation to gravity - body workers have become curious if this concept could explain our joints’ ability to hinge without a pin. Then Dr Stephen Levin, an orthopaedic surgeon, coined the term Bio-Tensegrity.
Dr Levin was curious as to why, no matter how hard you tried, you could not completely close the space between the tibia and the femur. Using tools to measure the distance, he and his surgical team would try to press these two bones together to no avail. So when he learned of Fuller’s work in tensegrity structures, where no compression structure (i.e. bone) can never touch another - no matter how much you try - he realised the missing link in our understanding of Bio-Mechanics. . .Tensegrity.
Whilst understanding Bio-Tensegrity fully is a topic for another day, simply put - Our bones float in a web of soft tissue that actually holds every bone away from its neighbour.
Let’s come back to our hinging knee, where we believe the Femur sits on the Tibia and articulates without a pin through the axis of rotation. In a traditional column paradigm, without a pin the femur would press against the tibia and very quickly the friction between them would destroy the articulating surfaces. In the Bio-Tensegrity model however, the Femur never touches the Tibia . . . Ever! So as we flex and extend the joint the tissues have space to glide freely.
This is a huge shift. It means that posture isn’t just a case of ‘stacking’ bones in the best orientation so gravity can load them - like Nelson’s column. Instead, if we are nicely aligned in optimal posture, we will actually be pressing back against gravity, creating space in our joints, rather than being pressed down with it. Now that takes some getting your mind around!
Is Static Posture So Static?
The fact that we are contained between the Earth and Gravity gives us something to push against. And this is very important because, for tensegrity to work, we need a compressive force equal to a resistive force. This makes static posture a dynamic activity. We are constantly being moulded by these forces, and healthy tissues therefore require optimal length/tension relationships, along with quality nutrients and a positive mindset, in order to resist the constant force of gravity trying to squash us into the Earth. This idea can be illustrated with a simple core activation exercise. Instead of performing crunches with the abdominal muscles as you see in gyms the world over, the deep core actually responds to expanding (stretching out). The quickest and simplest way to activate the core is to lay on your back, with your arms above your head and attempt to roll over by stretching out further, without using your legs. This movement instantly engages the deep core to create ease of movement. To see how much easier, try laying in the same position, tense your obliques and rectus abdominis and now see if you can roll.
Why does this illustrate tensegrity on the body? Because expanding out instead of contracting in, actually frees up our movement.
Another great example is found in walking. Try walking with your shoulders rounded and looking down at the ground. Get a sense for the weight of your legs, especially at the hips. Now imagine you are being pulled up by the top of your head towards the clouds. Think like you are expanding. Now walk and pay attention to your legs and hips now. Do they feel lighter?
So, if we are gently pushing back against gravity and opening up our joint and tissue spaces we should, in theory, be pain free. If not, joint space diminishes, tissues are put under stress, blood flow gets restricted and pain develops and persists.
Postural Alignments and Tensegrity
Once we let imbalance creep into the body, we stop efficiently pressing out against gravity. Each postural deviation - (Hyper) Kyphotic/Lordotic or Sway will result in a slightly shorter person. Remember when you were a kid, being measured by your dad against a wall chart, trying to expand yourself just that little bit more? I doubt you ever tried to get a little taller by tensing all your muscles, rounding your spine or increasing your flat footedness!
The cells of the body have a great ability to mould themselves into whatever container shape they are given. If you are hyper-kyphotic the cells of your body will mould to fit that shape, if you have valgus knees you’ll mould to fit that shape too. The problem is you stop pressing out against your gravity container and only expend enough energy to press out against your body container. Has anyone ever told you “You look like you have the weight of the world on your shoulders”? Well . . . You have. . . it’s called Gravity!
The term Biomechanics refers to our movement. Not just gait, but all movements we make, from the small movements it takes in typing this article, to the compound movements involved in bowling a cricket ball. So how does our model of Bio-Tensegrity fit into this form of biomechanics?
To produce movement we combine both Open and Closed Chain environments.
Open Chain means that we remain grounded and the object we place force upon moves (in the direction of our force). Our arm is usually Open Chain for example. If we lift our new iPhone to our ear the phone moves openly in the direction of our force (towards our ear).
Closed Chain means that the object we place force upon remains fixed and this forces us to move. As we walk our stance leg is in Closed Chain as it exerts forces on the Earth. The Earth can’t move (relative to our force at least!) so we do. Our non-stance leg is in Open Chain though, as it swings our smelly old trainers forward.
We mentioned earlier that we are contained between the Earth and Gravity. As we press out against these forces we are able to maximise the space between our joints and tissues. By doing so we allow each and every bone to glide across its neighbour without friction and move between Open and Closed Chain environments. We do this by utilising energy in two ways.
Earthing and Un-Earthing
We can break movement down into two phases, Earthing and Un-Earthing. Let me explain.
Earthing = Closed Chain. We absolutely have to ‘Earth’ any force generated by our muscles. By this I mean that any force we generate, whether walking or lifting an object, gets placed into the ground through our body.
Gait requires us to force our body weight into the ground then attempt to sheer the connection by pulling one foot behind us. If we were stood on a Swiss Ball and walked, the ball would roll backwards in the direction of our force (open chain). Fortunately for us the Earth has a tad more mass than a Swiss Ball so the Earth remains still and we move forward in the opposite direction to the force we applied (closed chain).
Un-Earthing = Open Chain. Lets take lifting a suitcase onto the scales at an airport check in as an example. We need to Un-Earth the bag to lift it 30cm or so up onto those scales. But unfortunately for me, my wife’s suitcase just won’t seem to un-earth itself! Therefore my use of Bio-Mechanics must do it for me. So I bend over heave the weight off the ground and sustain the compression through my joints just long enough to dump it down on the scales above. Phew!
Hang on a minute!
What happened to all that force I generated in lifting that suitcase? Well. . . I Earthed it.
Remember, ‘We absolutely have to ‘Earth’ any force generated by our muscles’. That suitcase weight has to become part of my own weight for a brief moment in time. It has to pass through me into the ground. That means I can’t just lift that suitcase with my Biceps Brachii, I can’t lift with only my Lumbar Erectors and I can’t lift with only my Hamstrings. I have to lift with all my muscles that link the handle of that suitcase to the soles of my shoes.
Shouldn’t Everyone Blow Their Back Out Going On Holiday?
Fortunately, no. Although they would if only Bio-Mechanics were at play. If we were a system of pins and compression joints the 20kg (+!) suitcase would excerpt 20kg more friction force on my joints. But remember Dr Levin? He couldn’t manage to get the Femur and the Tibia to touch each other. That means our joints are not under friction. Whilst 20kg is added to my bodyweight, if I were to stand on a set of scales when lifting it, the weight is actually dissipated throughout all the tissues of my body. Saving my back for a nice golden sun tan rather than the surgeon’s knife.
So Why Do People Blow Their Back Out Lifting Suitcases?
This model of Bio-Tensegrity has one fatal flaw. Motor patterns.
Let’s not forget that we are nervous system driven. If not for our nervous system we would simply be a beautiful tensegrity structure resting motionless on the floor, like Buckminster Fuller’s sculptures. Our choices of movement are largely based on habit and largely based on imbalance. One might think this is a ‘Chicken or Egg’ question. Did our habits develop our imbalances or did our imbalances develop our habits? It’s pretty easy to argue either side of this question and neither are wrong.
I’m going to argue the former however, because healthy humans are born without fascial restrictions. Our environment develops them. Mum may never have put us down on the floor but instead moved us between being held, to laying on a soft mattress, to sitting us up with cushions all around us so we wouldn’t fall over, to the use of baby walkers - so never developing our freedom of movement. If we got through that unscathed, we likely sat in a chair at school and at home, restricting our hip flexors and the full length growth and mobility of our peripheral nerves. How about stress! Could that change the way you move chronically then produce fascial restriction? I think so. If we were to have full free range of movement in an environment where we walk, run, climb, deep squat, wrestle and dance then imbalances may only appear in very small amounts compared to how we see them today.
So why do people blow their back out lifting a suitcase? A combination of poor movement choices over a lifetime, compounded by ever increasing fascial restrictions that distort our optimal tensegrity balance.
Even recently I bit my tongue when a professional bodyworker said to me you can’t forward bend without spinal flexion. You can. In fact, when lifting a 20kg suitcase, you must! Your lumbar spine will only begin to flex when you get to the end range of hip flexion - on average about 45 degrees (that’s Bio-Mechanics. I apologies!!)
If your movement choice is to compress rather than expand when you forward bend, you will flex your spine towards the compression. But you just broke the rules of Bio-Tensegrity - you didn’t expand - and drifted quickly into the rules of poor motor skills. And we’ve established this is not where you want to be.
You cannot, I repeat, cannot Un-Earth and consequentially Earth anything safely if you begin in a compressed state. The load will only have one way to go, through your joints. But if you press out against gravity and use it to expand your joint and tissue spaces, you will Earth the load through every tissue of your body.
We saw this in our walking example, where the hips and legs became lighter once we expanded the dynamics of our posture.
So the Bio-Mechanics of lifting - The degree of dorsiflexion, knee flexion, hip flexion and spinal leverage - also requires us to add one element to correctly include Bio-Tensegrity - Expand.
Whilst it is my belief that our environment and movement choices initially create our imbalances, you can’t usually resolve the problem through movement choices alone.
Indeed, we may have begun with our movement choices and environment developing our imbalances but quickly the imbalances will have taken over and begun to drive more imbalance. This is an ever decreasing circle looking for equilibrium. But it won’t be found in trying to stand up straight when someone tells you to. In the facially restricted (hypo-mobile), you’ll need to loosen up the restrictions before you can change the habits. In the facially unrestricted (hyper-mobile) you can strengthen them up and choose good habits.
So to improve the Bio-Mechanics of the client and reduce their pain you’ll need to do a simple three part assessment.
Part one - Categorise their posture both static and in motion. If they are slightly shorter than they should be, either standing, sitting or when they move, then they’re not expanding out.
Part two - Are they Hyper or Hypo Mobile? To find out do a range of motion assessment and also feel the quality of their joint motion.
Part three - Make a plan! If they’re floppy in all ranges of motion then maybe they need to see someone who can teach them how to keep their joints in a safe range of motion and strengthen them up to tighten up the tensional components in their tensegrity body. If they are stiff, then get to work improving tissue mobility wherever you feel is going to have the most impact in the time you have available.
We started off this article talking about Bio-Mechanics. Within this field of study we can clearly explain the angle, loads and forces applied to the human body. But it is important to remember not to think in compressive terms.
Bio-Tensegrity allows us to explain how our joints can achieve these angles, loads and forces without friction destroying the articulating surfaces. This is clearly important to the health of our tissues. The overriding thought when engaging with tensegrity is to Expand. Expanding increases joint space, loads our connective tissues and frees our movement for the optimal Bio-Mechanics to work efficiently.
If we don’t expand we will compress and this unloads the fascial network and increases instability, which in turn leads to greater instances of injury.
But never forget, we are nervous system driven creatures. Unlike plants that can be explained perfectly through a tensegrity sculpture, we must choose our movement. Remember, poor movement habits are likely to develop fascial adaptations because fascia is laid down over lines of stress.
Your job as a soft tissue therapist is to work out whether a length/tension relationship needs balancing in your client, or whether they are simply not controlling their joints due to hyper-mobility.