How Kenneth Snell discovered tensegrity
When kenneth Snell first created a tensegrity structure, the path towards that structure was paved first with a sculpture of an arrangement of slim rods with weights at each end, each suspended from another via an overhead wire. Similiar to children's toys or mobiles, these rods would sway when perturbed. (And unsaid by him, they would return to a balanced position).
He then built a variation of this, suspending the rods from below with an arrangement of wires. In both cases, the geometry of the individual pieces allowed successively higher pieces to be supported by those below.
With the final sculpture, the one that inspired structures which where thereafter named by buckminster fuller as tensegrities, kenneth got rid of the weights and replaced them with additional tension elements (in other words, more wires.)
Referencing this sculpture in his words, "while forfeiting mobility, I managed to gain something even more exotic, solid elements fixed in space, one-to-another, held together only by tension members. I was quite amazed at what I had done."
Note the observation about reducing mobility:
To evolve a tensegrity from the primitive structures, he inhibited the mobility of those structures.
Does the body as a whole act as a tensegrity?
A common tendency these days, particularly when referring to tensegrity in the human body at the level of movement and posture is to state that the body acts as a tensegrity.
I'll suggest from the get go that this is a mistake. Tensegrities, as Kenneth observed, lack mobility. While structures within our body like the skull, the pelvis, and our synovial joints all require tensegrity in order to withstand the stresses life puts them through, our body as a whole, whether in motion or holding a pose, is not.
But it can be.
Where our body does have tensegrity
While tensegrity exists at the level of the cells, and is an important quality for joint lubrication and for allowing non-synovial joints like the skull sutures to adjust when accounting for growth and other changes, at the level of movement and posture, the human body acts as something else. I'll call that something else "a liberated tensegrity structure" or liberated tensegrity for short.
At the level of posture and movement, Tensegrity is an option
The implication here is that in terms of movement and posture the human body can assume movements and posture with the properties of a tensegrity. And it can also assume movement and postures that lack this quality.
As an example of the latter, lying on the floor, totally relaxed, the body is anything but a tensegrity. Going to the other extreme and bracing the body beyond the ability to respond instantaneously to externally applied force, the same thing can be said. The posture doesn't have the qualities of a tensegrity.
Playing a martial art like tai ji, in particular push hands, parts of the body can be substantial and others insubstantial. The former could be related to tensegrity while the latter not.
Is light a wave, a particle, or both?
The argument between two imaginary factions, those that oppose the idea that the body acts as a tensegrity and those that don't could be compared to the arguments between scientists a few centuries ago about the properties of light. Is it a particle? Is it a wave? Eventually, someone figured out that light acts as both.
And likewise with the human body and tensegrity. Sometimes it can act like a tensegrity, sometimes not. It depends on context, and, how we choose to use it.
So why use the term liberated tensegrity in the title of this article?
What is liberty
Liberation can mean different things to different people. For myself, I understand liberty or freedom as the ability to choose the limits we act within. The freedom is in the ability to create limits for ourselves, and then to get rid of those when they are no longer useful, or when we simply want to change what we are doing.
The better we are at sensing limits, changing them, and also, acting within them, the more freedom (or liberation) that we have.
The difference between smartphones and regular phones
It's a lot like the difference between smart phones and regular phones. Smartphones are, if you like, more liberated, because they can act in different ways.
The more apps you have, the more freely you can use the phone. And here again limits can come into play. If you are good at defining what it is that you are trying to do, i.e. creating limits via that definition, even if you have so many apps on your phone you don't know what to do with yourself, with a clearly defined idea of what you are trying to do you can pick the app that does the job.
I've said this in other places, but an important question to ask about smart phones is "what makes them smart?" Their smartness is due to their ability to sense and respond (Using the same piece of hardware no less). That in turn is the basis for their liberation.
With liberated tensegrities such as our body, the variable tension offered to us by muscles and connective tissue, joints and bones allows us to choose whether to format ourselves as a tensegrity or as something different. We can choose the limits. Those limits can be determined by whatever it is that we are trying to do.
With our body, the equivalent to a smart phones touch screen is our muscles. They give us the ability to move our body and stabilize it. They also allow us to "sense" how the parts of our body relate.
Why bother with the tensegrity option?
Why bother with the tensegrity format? (and why bother with the word tensegrity in the title if tensegrity is only an option?)
A tensegrity offers sensitivity and robustness with minimal effort.
I should point out here that with our body, we can sense touch via skin contact. However we can also sense force via muscle activity and connective tissue tension.
In this regard it's a little like tuning a guitar, or even just tightening a string sufficiently to give it tension. Pluck it and it responds instantly as if sensing the pluck.
Our bodies can be used in the same way.
A tensegrity is instantaneously responsive
It bears mentioning here that one of the more important hallmarks of tensegrity isn't so much the idea of compression elements floating within tension elements, but rather the sensitivity and instant responsiveness as well as "whole body connectedness" that tensegrity structures offer.
When subject to a force, no matter where and no matter whether it works to compress or stretch, the tensegrity structure so acted upon will distribute that force within itself. this re-distribution is complete so that all elements share the load. In addition, this happens without delay. The structure doesn't think or process. It simply responds to the force by redistributing it within itself.
Tuning tension within our body
Within our bodies, if we adjust tension within our body, not too much, and not too little, we can notice any force that impinges upon our body instantly. You could think of this as "tuning tension".
Depending on our training and our intent, we can use the impinging force in a number of ways.
If we are fighting it can trigger a defence or counter attack, the incoming force helping to drive that counter attack. If dancing, it can be used in such a way that the dancers move together. In any case, configuring our body as a tensegrity, we make it instantaneously sensitive to any force or change in force that acts on it.
Sensing change and responding with zero lag time
As an instance of sensing change and responding using the force of the change itself, I was once crossing in front of a stopped car. The driver was looking behind him for a gap in traffic so he could reverse and park. I knew that he might choose to drive forward without looking so I place my hand on the bonnet as I walked by. Sure enough he started forwards without looking first.
The initial movement of the car was transmitted via my hand and pushed my body forwards.
The driver noticed and stopped. No harm done (and his wife apologized.)
Had I not had my hand on the car, the car would have hit my leg and I probably would have suffered injury. But because I was in contact, and ready, it simply pushed me. I'd had enough tension in my arm that the force of the car moving forwards was transmitted to the rest of my body.
In tai ji, one of the most basic lessons is to relax where ever you are pushed. It's a tricky game because we normally tend to resist being pushed. And so relaxing the part of our body that is in contact so that our partner can't push our body is part of this game. And this is where the idea of liberation comes in.
The freedom to stiffen or relax
With the ability to turn tensegrity on or off (or at the very least, being able to turn tension on or off) we have the freedom not only to configure our body or movement, but the amount of stiffness in various parts.
Thus, playing tai ji push hands, we can relax when we are pushed and where we are pushed, while remaining integrated in other places.
Scaleable stiffness for dealing with force differences
This stiffness is scalable. And because of that, it allows us to deal with varying degrees of force, say while lifting weights.
And that's another way that a liberated tensegrity structure is useful.
A lot of people who study the body will say things like the muscles that work the fingers originate in the forearms. And that is an important observation. The mistake is in thinking that the forearm and shoulder have to be engaged in every movement of a finger. It depends on the total force the tip of the finger is working against.
If you are lying on your back, you could possibly bend the finger slightly. You may be able to use muscles that are intrinsic only to the hand. However, working against greater force (or to create greater forces) you'll have to recruit muscles further up the chain. This is in part to protect joints, but in part it's to make work requirements scalable to whatever the work being done is.
Dealing with greater forces requires better integration
For myself, lifting weights, I've found that above a particular weight I start to get pains in particular parts of the body. And by learning particular muscle activations, that pain goes away.
I'd suggest here, that over and above a particular weight, more muscles, further afield need to come into play to bear the weight and also to protect the joints.
Pain is a signal that integration has not been achieved
If for some reason a muscle isn't functioning, the brain triggers some response, in my case, pain, to indicated that the body is in danger and to ideally stop what it is that you are doing, so that you can change the way that you do it.
And so learning to activate the recalcitrant muscle, I find I can squat happily with the heavier weight.
In general, the greater the force you are dealing with, or are trying to create, the more of your body you have to use as an integrated whole. And that too is the advantage of our bodies acting as liberated (or if you like "scaleable") tensegrities.
Better connection equals better integration
The more connected the parts of the body become, the better it can act as an integrated whole. Meeting greater loads with greater tensegrity (or scaled up tensegrity) means that there is more tension elements within the body brough on line to share the load.
A different style of tug o' war
It could be like a scaleable tug o'war team. Initially they might have a few people on the team. Then as the load increases, more players are called into to deal with the load increase. As the load drops, players can be called of to relax.