Saturday, May 11, 2013

the nature of chi and the value of imagination

Just glancing at the title above, you might think that I am about to take the position that chi is imaginary. Nothing could be further from the truth. In my view, chi is very real, but at a level of abstraction that would be intangible, were it not for the immense computational power of the cerebellum.

Understand that I'm not talking about symbolic computation, but something more comparable to what an analog computer does, performing accumulations and other transformations on combinations of inputs (usually either current or voltage levels) to produce outputs in a useful form. In the cerebellum, the inputs and outputs are patterns of neural activity, and the available transformations include rates of change.

In calculus, a rate of change is referred to as a derivative. An example commonly used in conveying the concept is the sequence: position, motion, and acceleration. Motion, being a rate of change in position, is its first derivative. Acceleration, being a rate of change in motion, is its first derivative, and the second derivative of position. The next step in this sequence is variously termed jerk, jolt, surge, or lurch. Jerk is the rate of change in acceleration, and therefore its first derivative. It is also the second derivative of motion and the third derivative of position.

Before getting into how this relates to the cerebellum and the subjective experience of chi, I need to introduce another set of concepts: mass, force, impulse, and momentum. Mass is like weight, and is in fact proportional to weight if gravity is held constant. Weight is the force exerted on a mass due to gravity, and in fact varies slightly from one location to another across Earth's surface, despite being measured using a constant mass. But force isn't limited to gravity. Electrical and magnetic fields can also exert force. So can flowing air or water, or the skin of one's fingertips when throwing a ball.

Momentum is the multiplicative product of mass and velocity (motion or rate of change in position). Velocities are produced by accelerations. Mechanical force is commonly defined as the multiplicative product of mass and acceleration, and impulse is the multiplicative product of force and time. If mass is held constant, force is proportional to the rate of change in velocity, which is to say that it is proportional to acceleration, and impulse (force x time) is proportional to the accumulation of change in velocity. With variable mass, force is the rate of change in momentum, and impulse is an accumulation of change in momentum.

The thing about impulse is that it is agnostic with respect to time. Time is factored out. A given impulse can represent a small force over a longish time or it can represent a strong force over a very short time. To fold this back into the above discussion of motion and its first and second derivatives, an impulse delivered as a small force over a longish time has a low jerk factor, whereas an equivalent impulse delivered as a high force over a short time has a high jerk factor – a sudden, sharp change in acceleration.

Jerk can result from a hard body part, like the skull, coming into contact with an unyielding surface, like a brick wall, or it can result from a coordinated explosion of neuro-muscular activity. Either way there is some potential for injury, and part of what the cerebellum does is to avoid dangerous extremes.

Now, to come full circle, I believe chi to be the subjective experience of momentum, force, and (most notably) impulse [and the projection of these a fraction of a second to a few seconds into the future - 25Sept2016]. Imagination figures in because the cerebellum will just as happily estimate these quantities for imaginary objects and fanciful circumstances as for real objects and circumstances – whatever is presented to it, so long as that presentation is vivid and convincing. Imagine yourself doing some difficult movement and your cerebellum will issue the instructions to perform it, the danger being that if you lack either the strength or the range of motion you may end up on the ground in a heap.

Imagination is seldom as convincing as reality, but it can still produce an effect on the cerebellum's output. Moreover, in some cases, as with the square root of minus one, the imaginary nature of what's presented to the cerebellum can factor out. For example, if you imagine passing a ball back and forth between your hands, the additional impulse needed to accelerate the imaginary ball results in your arms moving faster than they otherwise would, but by the time those forces are transmitted to your legs, there is no discernible difference between an imaginary ball and a real one. Another example, if you want to build strength for faster side-stepping, imagine that you are standing over the pivot of a teeter-tooter, having to push yourself up as well as sideways with every sideways step.

I rather like the effect of imagining the handling of a ball, about the size and mass of a volleyball, sometimes incorporating this into my practice, and, because I spent so much time doing so, it's relatively easy for me to imagine the handling of an end-weighted staff convincingly enough that I can practically feel its weight in my hands. I expect this is similar to arts, like Escrima, in which one starts out using sticks and then progresses to empty-hand.

Caveat: I have attributed neural activity which is distributed through other parts of the brain to the cerebellum as a simplification. It's true that the cerebellum plays a pivotal role in coordinating movement. That it does so in close cooperation with the brain stem and midbrain seems beyond the scope of the present purpose, although the reader may be interested in pursuing greater detail.

Sunday, May 5, 2013

on symmetry and long lines

Whether recirculating or reciprocating, exercises may be bilaterally (left/right) symmetrical, but aren't necessarily so. Exercises that are not bilaterally symmetrical should be performed on both sides (both mirror-image versions) to approximately the same degree.

There are other symmetries, which can usually be described in terms of rotation, either circular movements or the twisting of a hand, foot, shoulder, or hip to its limit. Circular movements are generally reversible and should usually be performed in both directions. Twisting may also be reversed, although doing so usually causes the original motion to become awkward and in need of other modifications if it is to continue to flow smoothly.

Gently oscillating between opposite twists is a fine, and a good way to familiarize yourself with the limits of movement, but doing so can quickly become boring. It helps to combine joints, for instance rotating one hand as far as you can, twisting shoulder, forearm, and wrist all in the same direction, perhaps twisting the other hand at the same time, either in the same direction or in the opposite direction.

By combining arm/hand and leg/foot twisting together, you will discover that there are stress lines, like rubber bands pulled tight, which you could trace through muscles and tendons, extending continuously from toe to fingertip. These are not the meridians of Chinese medicine, but a chain of tissues that are all being stretched at the same time. You'll also find that the second step in reversing the twisting motion (after relaxing the muscles that put you into a twist in the first place) is to contract all of the muscles along that chain, and that if you continue to do so the result will be an approximately opposite twist.

These long lines, composed of chains of muscle and tendon, when uniformly stretched and developed, are capable of generating movement that is both graceful and powerful, because it involves the entire body.

Thursday, May 2, 2013

walls and the cerebellum

A wall is something that stops you, anything that stops you.

If you overdo exercise, exhaustion and soreness can become a wall.

If you do your exercises mechanically, the same way every time, boredom can become a wall.

In the context of the martial arts, if you concern yourself overmuch with application – how effectively a sequence of movements might be applied in combat – or with precise form and maximal dynamism, you may find that you've walled yourself off from all of the various possibilities that can be present at each step, in a more playful approach. And, too, there's legitimate reason for concern that practicing in a violent manner can make one more likely to participate in or even initiate violence, and less apt to take the opportunity to avoid a needless fight.

Similarly, I'm finding that the effort to accurately describe something that is never exactly the same, should never be exactly the same from one moment to the next, can become a wall, both to the work of description and to the practice.

On the other hand, there are still a few ideas that I have yet to touch on, the theory that I mentioned in the original post on this blog.

You already have the basics, stances (with particular attention to positioning of the knee) and recirculating arm motions supported by subtle alterations of those stances (reciprocating motions when exploring cusps), and a small collection of principles to act as a guidebook. While I prefer not to constrain your imagination with respect to what motions you might wish to include in your repertoire, I hope and intend to fill out that guidebook.

Reach to the back of your head and find the little bump at the top of your neck. On the inside of your skull, most of the tissue within a couple inches of that point is contained in the cerebellum. The cerebellum is fundamentally an integration machine. (Integration, along with differentiation, form the basis of calculus. Integration is essentially the accumulation of an effect as the factors creating that effect also change.) The cerebellum measures the effect of various and varying forces upon momentum, your momentum or that of something you handle, throw, or sense remotely. It also makes predictions about the effects of forces that haven't yet occurred. And it does all this incredibly fast, but it needs experience upon which to base what it does.

Along with stretching, strengthening, and mild cardiovascular exercise, the main point of practice is to provide the cerebellum with some experience upon which to base its predictions. The more varied that experience, the better able it will be to handle something totally novel, something it has never had to deal with before. Also, the more diverse the range of situations with which it has learned to cope, the more gracefully it will be able to guide your motion under ordinary circumstances.

The upshot of this is that it is better to ferret out the essence of what your body wants to do today than to stress over whether you are performing some movement correctly. Protect your knees, find something soft to land on if you're doing something that may cause you to lose your balance, and otherwise allow your cerebellum sufficient license to explore variations on motions, even beyond the point of their becoming unrecognizable. Thus liberated, it will guide you well.