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Mario Tobias
08-04-2011, 07:40 AM
hey, I've got a theory and would like to get your thoughts.

I thought about it recently. Is the amount of power generated from body parts proportional to how wide the range of motion is. we can then rank body parts like is the wrist more powerful than the elbow, and are these 2 more powerful than the shoulder?

everybody's saying that dont use shoulder power, and use more wrist or elbow. is this because the shoulder has a limited range of motion compared with the 2? or transfer power to the knees rather than use shoulder. is this because the knees have wider range of motion vs shoulder? using this analysis, the center should have the widest range of motion since this should be where most power needs to get generated?

lbb
08-04-2011, 07:48 AM
I don't think it's exactly range of motion. It seems to me that the techniques of aikido rely more on the muscles of extension rather than the muscles of contraction (which is, I think, where most people tend to go to when they try to do something "powerful"). I don't think it's really a matter of "using more wrist or elbow" -- if you did exactly that, I don't think you'd like the results. But as a visualization, that might help someone to stop using the muscles of contraction so much and let the muscles of extension do the job.

Tim Ruijs
08-04-2011, 08:05 AM
You can only exert power in relation to something, linear or angular.
The base to which this force relates must be strong/stable enough to dispose the counterforce.
take for example a wrist, it can move only so far before it reaches its natural stop position (given a certain direction). Exert more force and two things can happen: one you start moving other body parts to dispose the exces force (neutralise it), or you stay fixed and other body parts must dispose the exces force. Obviously there is literally a breaking for any body part where it no longer can handle the applied force.

Rather than looking at individual body parts I would look at the chain of body parts and the base that carries that chain.
hope it makes sense

dps
08-04-2011, 09:00 AM
Rather than looking at individual body parts I would look at the chain of body parts and the base that carries that chain.
hope it makes sense

Its like cracking a bullwhip.

http://www.new-pony.com/systema/bullwhip.html

dps

chillzATL
08-04-2011, 09:19 AM
I don't think it's about generating more or less power. I mean it's pretty well proven that we can generate a lot of power using our shoulders and upper body strength. It's more about what you give up when you do that. Pushing with your shoulders seems to raise your center of gravity into your shoulders. Go push on something that doesn't move using your shouders. You can only push so hard before you simply push yourself back and over. Do the same to a person who is shorter/stronger than you and you effectively give them your center, put them under you. You can counter than to some degree by leaning, driving with the lower body, etc, but you're still giving up balance/stability/equilibrium in other directions when doing so. Training and conditioning the body to be relaxedly connected and to move from the center avoids that. There are other benefits as well, but even in those cases I don't think it's about simply generating more power.

dps
08-04-2011, 09:22 AM
Its like cracking a bullwhip.

http://www.new-pony.com/systema/bullwhip.html

dps

"..... To crack a whip powerfully, accurately and dramatically does not require a great deal of strength. If the form is correct, the physics of the whip will allow the cracker to reach supersonic speeds with relatively little effort."

dps

Tim Ruijs
08-04-2011, 02:42 PM
"..... To crack a whip powerfully, accurately and dramatically does not require a great deal of strength. If the form is correct, the physics of the whip will allow the cracker to reach supersonic speeds with relatively little effort."

dps

This sounds more useful when doing atemi/strikes.

Energy is stored in the whip while moving. When suddenly changing direction, the tip must follow as it is connected to the base. Change the direction at the right time and the tip must move extremely fast to catch up. But this is explosive power.
It shows that little movement of the base can exert a lot of (explosive) power at the extremities. But how is this useful?

Mario Tobias
08-04-2011, 03:00 PM
well its just a theory of mine anyway. of course, an individual body part in itself is weak compared to if you combine several parts moving as one but its just logical to me that body parts can be ranked.

Don Nordin
08-04-2011, 03:10 PM
Maybe I am thinking about this all wrong, but I do not focus on generating power one way or another I try to work with and reddirect the energy of my Uke or opponent. That siad as soon as I mess up and let my arms or legs get outside of my center then I need to generate force to be able to stay in the game, if possible. But in this case power is substitue for sloppy form. :ai: :ki: :do:

Tim Ruijs
08-04-2011, 03:24 PM
well its just a theory of mine anyway. of course, an individual body part in itself is weak compared to if you combine several parts moving as one but its just logical to me that body parts can be ranked.
Well, there is a whole theory about body dynamics. A lot of mathematics involved to determine the influence of a node to the body. It might give you an idea of what happens when you move your arm, leg, hand. When you add rotation it becomes even more complex (and realistic).

You could probably rank them somehow, but the relation is not linear and depends on the position, angular speed of other parts. The ranking would also be dynamic. Ok, that is enough theory....

jester
08-04-2011, 03:55 PM
well its just a theory of mine anyway. of course, an individual body part in itself is weak compared to if you combine several parts moving as one but its just logical to me that body parts can be ranked.

Have you ever ran into the corner of a table at night?

The table doesn't move at all but it hurts nonetheless. In my experience Aikido is very similar.

JW
08-04-2011, 07:02 PM
My wrist and knee have similar angular range of motion, but the force that my quads can produce is much greater than the wrist articulators. I think there are only 2 things that determine the power of a joint.... how thick it is and how long it is.
Uh, that is, regarding the muscle at the joint. How many actin/myosin motors are present (muscle thickness) and how long the moment arm of the tendon's attachment to the bone is (that is, how much torque per unit force is produced).

At any rate.. I think that sort of muscle usage is exactly what we are learning NOT to do in aikido. For instance, we've mostly all seen "unbendable arm." That is supposed to have to do with ki and extension from the center. As opposed to having to do with the triceps.

danj
08-05-2011, 04:31 AM
The bulllwhip is a nice version of a passive 'kinetic chain'(google it) used a lot to describe physical locomotion. For the whip analogy imagine additional muscles along the bull whip firing at the correct time to aid the transfer of power from the handle out to the tip. Could consider the hips as the handle harnessing the ground (a source of infinite power) and propagating it out to the wrist (tip of the whip)

Similarly the transfer of this power to uke's hand and backward through their kinetic chain to create large movement/throw (the analogy sort of breakdown a bit though because the mass segments are the wrong way around)

Tim Ruijs
08-05-2011, 05:45 AM
The bulllwhip is a nice version of a passive 'kinetic chain'(google it) used a lot to describe physical locomotion. For the whip analogy imagine additional muscles along the bull whip firing at the correct time to aid the transfer of power from the handle out to the tip. Could consider the hips as the handle harnessing the ground (a source of infinite power) and propagating it out to the wrist (tip of the whip)

Similarly the transfer of this power to uke's hand and backward through their kinetic chain to create large movement/throw (the analogy sort of breakdown a bit though because the mass segments are the wrong way around)
How would that work for you in Aikido besides correct atemi/strikes?
I would think that you do not want to exert that much force on aite. The other way around: aite should not be able to take your center by loading it with his power/force. Correct ma-ai solves this btw.
And throwing aite harder? why?

danj
08-05-2011, 09:19 PM
How would that work for you in Aikido besides correct atemi/strikes?
I would think that you do not want to exert that much force on aite. The other way around: aite should not be able to take your center by loading it with his power/force. Correct ma-ai solves this btw.
And throwing aite harder? why?
Agree completely, there is no need to throw harder, you just up the efficiency in power generation and unloading so you do even less

- ma-ai in positioning and timing are the setup that reduce the power you need to unbalance
- being able to generate the power effortlessly/efficiently means you need to do even less to unbalance/throw

best,
dan

Erick Mead
08-07-2011, 01:06 PM
This sounds more useful when doing atemi/strikes.

Energy is stored in the whip while moving. When suddenly changing direction, the tip must follow as it is connected to the base. Change the direction at the right time and the tip must move extremely fast to catch up. But this is explosive power.
It shows that little movement of the base can exert a lot of (explosive) power at the extremities. But how is this useful?
Terry Dobson used the whip as a training tool frequently. I discuss some of that here. (http://www.aikiweb.com/blogs/but-why-7854/whips-and-chains-2960/) (which, from 32K views, seems to strike a chord, somewhere)...

This strobe-motion set of photos is helpful in understanding the dynamic-- where the chain falls faster (accelerating more in fact) than the ball falling by gravity beside it, because of conserving the angular momentum of its internal rotations. [The white dotted line shows the the simultaneous positions of the chain tip and the ball, which are dropped at the same time.]

At first the chain concentrates the building momentum out to full extension -- then dissipates it on rebound. Concentration and dissipation are part of the hachi riki used to describe the art This is the form of the arms in funetori undo, among other things.

http://www.aikiweb.com/gallery_data/526/chain_falling.jpg

Janet Rosen
08-07-2011, 04:20 PM
Have you ever ran into the corner of a table at night?

The table doesn't move at all but it hurts nonetheless. In my experience Aikido is very similar.

:D Great!
To return to earlier post by OP re generating force with say wrist or elbow: I see those purely as connectors/transmitters that shouldn't add force per se but CAN affect it's direction very nicely.

Mario Tobias
08-08-2011, 01:02 AM
Have you ever ran into the corner of a table at night?

The table doesn't move at all but it hurts nonetheless. In my experience Aikido is very similar.

But isnt the hurting in this case caused by a large pressure? because its a corner (small area) p= f/area, the pressure is very high. similar if you run into a nail. Power is proportional to force, displacement and velocity.