Yes, I posted in response to reading
"His prescription has to do with only turning the upper torso from the lumbar region, while the lower frame maintains a fixed "
And then the additional description from the other site of
“Yang Zhenji learned from his father that the waist is located just above the hips. Because of this it can turn while the hips and knees remain fixed in place."
And the emphasis re explosive torque at that site.
Your posting aimed at needed clarification of the kua's movement, my comments aimed at clarification of what happens re spinal movement.
My concern was with skeletal anatomy and skeletal movement in the torso, specifically ROTATIONAL movement of the spine.
The quotation specifically locates the ‘waist’ just above the hips and claims the the waist can ‘turn’ while the hips and knees remain fixed in place.
It can’t. The turning that takes place is thoracic spine rotation. And it is this turning which if done explosively, not within its normal range of movement, will result in damage to the lumbar spine.
I’m not making this up. This is from those posted links. Above the pelvis the only torso rotation that takes place is in the thoracic spine.
Part of the problem of getting clear about this is equivocation re ‘rotation’. Eg. claiming that if one turns the torso, that one turns the lungs, which results in a fallacy of attributing what is predicated of a whole to one of its parts.
When talking about rotation of the torso it is important to distinguish a number of different areas and types of rotation.
The skeletal aspects of the torso consist of the pelvis, the spine, and the shoulder.
Pelvic rotation takes place re the ilio-femoral joint, spinal rotation takes place in the thoracic spine and cervical spine.
Shoulder rotation is another kind of distinct rotation.
One of the links I supplied provides detailed information re these skeletal articulations.
"I think you may be inferring something that misrepresent the classical taiji understanding. Consider the classical metaphor of the qi being like a wheel, and the waist like the wheel’s axle. Given the time period, the person who called upon this metaphor would have had no experience of an axle that provided driving power to its wheel."
While your point is re origins of movement, ie. muscles, which was not a separate issue for me since any skeletal movement will involve muscles, there is an interesting aspect to this.
I am sure you would agree about the importance of metaphors. The "when you put an image in place of an image, then--".
Leaving aside the source of movement at a skeletal joint, what if the “wheel” were a millstone. A circular flat stone with a vertical axle and a horizontal lever by which rotating movement (torque)was imparted whether by man or some dumb ox.
Since one reason for my post was to prevent lumbar damage due to upper torso rotation it is millstone turning like movement that the lumbar spine is NOT designed for. And it is this sort of torque (Oxf. Moment of system of forces tending to cause rotation) that UPPER torso rotation transmits to the lumbar spine via all the relevant muscles if the thoracic rotation moves beyond its range of movement.
Re: qi being like a wheel, and the waist like the wheel’s axle and “it is rooted in the feet, issued by the legs, governed by the waist, and expressed in the fingers”.
You wrote: the lumbar spine is an important point of concentration, not because movement is generated from that point, but because it is an axis around which movement of the entire body orbits.
In my view, the lumbar spine is not like a wheel’s axle. So, the ‘waist’ will have to be located elsewhere. For me it will be a line just above the ilio-femoral joint, just about where the fabled dantian lies.
This is an imaginary axle not like an axle for a single wheel, but like the axle of a cart that can move the attached wheels from side to side.
In a real cart the movable axle is attached to a hub, called the ‘fifth wheel’, and the wheels of the cart are attached to this axle.
This is an analogy, so please, don’t equate this hub and its pin with the lumbar spine.
In the body this movement is achieved solely by the internal/external rotation of the femur on the pelvis, what is usually called the hip joint. Not the hip, but the hip joint.
In keeping with the title for this thread, this joint works best when one side is single weighted, when all the weight of the body is on a single leg. This allows the pelvis to rotate on a fixed femur, just like a post, leaving the other leg to do other stuff. Same bio-mechanics as in ordinary walking, all the muscles are there to fix the weight on one leg.
Because of the cryptic nature of the classics each word has to be carefully attended to, made more difficult, of course, because these are in Chinese.
The qi is like a wheel and the ‘waist’ like the wheel’s axle.
So, as the axle (of a cart) turns, so the wheels turn, in the sense of changing direction, side to side, as if advancing in folds. The wheels of a cart are also turning around the hubs on the axle.
The qi is like a wheel since when it reaches the fingers it is turning like a wheel.
Ie. the arms are turning like wheels.
This doesn't mean the arms are connected to the hips, only that the hips turn while the arms are also turning.
But this makes sense only if one’s arms actually turn like wheels or are turning as if turning a wheel.
Most Tai chi practicioner's arms don’t move like turning a wheel so this metaphor will not make sense.
As a quick aside, browsing through the mtsu board, I came across the ‘holding the ball’ thread.
Most people hold and move their arms as if holding a ball. Given that basketball was all the rage in China at YCF’s time, Chiang Kai shek was kidnapped during a game, and Tai chi was taught at the YMCA founded by Chiang’s father in law it comes as no surprise that this metaphor was used.
Many people when doing ward-off look like they are playing basketball.
But, back to the topic, re what you wrote re the lumbar spine
One common confusion is to mix up the idea of an axle and the idea of an axis.
Another confusion is to mistake the vertical vector for the center of gravity of objects, usually presented as a vertical line since that is the direction of the gravitational force, for either an axis of rotation or for an axle.
Here’s a link for the center of gravity:http://www.exrx.net/ExInfo/Posture.html
The lumbar spine is not really an axis around which the movement of the entire body rotates. It’s bio-mechanical function is otherwise.
The hip joint is a ball and socket joint which allows rotation in 3 planes, flexion/extension, abduction/adduction, and lateral/medial (external/internal) rotation.
It is the lateral/medial rotation that the hip joint allows which is at the root of ‘torso’ rotation. Ie. moving the body from side to side.
And so I have settled on the hip joints as the “axle” joint, let the pelvis lead the way, be the banner, which the wheels (the arms) follow while turning like they are turning wheels.
The lumbar spine I leave alone, its lordotic curve intact. It may well rotate along with the pelvis but only in the sense in which the heart rotates when the pelvis rotates.
[This message has been edited by RonKreshmar (edited 05-13-2003).]