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Old 01-25-2013, 02:50 PM   #30
Robert Cowham
Dojo: East Sheen Aikido and Kashima No Tachi
Location: London, UK
Join Date: Jul 2000
Posts: 279
Re: A simple mechanical model of body use.

Chris Hein wrote: View Post
The first problem I see here is that- muscles only contract. So every motion is really a 'pulling up' because it's a contraction. The muscles can't 'push' anything, they all contract, and make the body do different things because of their orientation in the body. So triceps seem to be making the arm 'push out' but really they are pulling on the backside of the arm to make the arm extend. Muscles work in opposing sets like this so we can get action on both sides of the body. We both are fully aware of this I'm sure, but I have to say this to make my next point.

If you use one set of muscles to support or lift a load, they are pulling. you can use an opposing set of muscles to pull in the opposite direction at the same time ('dynamic tension'). But you don't get a bonus result for this, you only expend more energy. Muscles can't help each other by using a complimentary 'push and pull' or 'extend and contract', they can only contract or 'pull'. So if you activate opposing muscle groups you are only costing energy and not gaining it.
I use the imagery of ropes and pulleys - so by pulling down on a rope with a smooth pulley at the shoulder, the arm raises. The question is: where is this initiated from? I imagine a rotating barrel/drum at the tanden which winds a rope connected through pulleys to the hand. I still think that muscles are involved, just that due to the overall integration, the muscles are involved differently to the "wrong" way of lifting hand/arm.

It's also interesting to try imagining the rope going from shoulder to hand, and not down the arm...
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