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  #11  
Old 02-01-2011
RadSwim RadSwim is offline
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Quote:
Originally Posted by terry View Post
The goal of Perpetual Motion Propulsion is to decrease reliance on muscle force generated by us, and increase efficacious use of naturally-occurring, and cost-free, forces.
What "naturally-occurring and cost-free forces?" The vital energy of the water? Psychic energy? Magical thinking!

Once the dive or push off is over, every bit of a swimmer's forward motion comes from his or her muscles. Not gravity, not magical forces.

I think (hope) that you mean to say that the goal of Perpetual Motion Propulsion is to decrease reliance on muscle force generated by the shoulders, and increase efficacious use of muscles throughout the body, particularly core muscles.

Efficient swimming happens when the swimmer learns to move his or her muscles in a coordinated manner to position the limbs in postures that maximize both streamline and propulsion. A good swimming coach teaches a swimmer how to move well. Should that not be the goal of TI?

Last edited by RadSwim : 02-01-2011 at 01:27 PM.
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  #12  
Old 02-01-2011
Lawrence Lawrence is offline
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Worth remembering also that what comes down must first be lifted up. So, however weight shifts are used to aid propulsion, the relevant weight must first be raised, and that takes muscular effort.

If one swam perfectly flat, of course, including spearing horizontally and executing the catch without first having to move the forearm from horizontal to vertical, then there would be no weight shifts to discuss.

Those that there are exist because we use our muscles to create them. I think the 'free' forces Terry is talking about are the weight drops which such muscular action allows us to play with.

Terry's insight here is unquestionable, I think, namely that weight shifts if used in a certain way can aid efficiency. The question is how that happens.

Last edited by Lawrence : 02-01-2011 at 02:39 PM.
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  #13  
Old 02-01-2011
Rupertdacat Rupertdacat is offline
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Quote:
Originally Posted by RadSwim View Post

... Perpetual Motion Propulsion ...decrease(s) reliance on muscle force generated by the shoulders, and increase efficacious use of muscles throughout the body, particularly core muscles.
Sounds about right to me...
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  #14  
Old 02-02-2011
drone drone is offline
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Disclaimer: I am not in any way conversant with the physics involved, but have thought about why this works, and have a theory.
By using the gravity/downward hip thrust/spear/lengthening, we are using our body shape in the same fashion as the Archimedes screw, an ancient water pump that used a coil design central section (think of rotini pasta) inside a tube. When the centre section was turned, water was drawn up the tube in the empty parts of the thread.
We are, in effect, using our lengthened bodies in the same fashion to advance through the water, rotating back and forth (rather than in a complete spiral), somewhat duplicating the twisted coil centre of the Archimedes Screw. Result - forward propulsion (instead of drawing water up a tube, it is sent behind us). I suspect it might be the same principle at work here.
http://en.wikipedia.org/wiki/Archimedes%27_screw
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  #15  
Old 02-02-2011
Thatchman Thatchman is offline
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Surely the benefit of using rotation and gravity rather than just more muscle (or only muscle) is that you will be more relaxed in the water with less muscle engaged. The benefits would then be better balance and body position hence less drag and hence more speed.

I get the logic but as a slower swimmer, I am not sure that i have the timing correct. I have tended to have an early pull. How much of the propulsive benefit would this cost?
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  #16  
Old 02-02-2011
terry terry is offline
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Quote:
Originally Posted by drone View Post
We are, in effect, using our lengthened bodies in the same fashion to advance through the water, rotating back and forth (rather than in a complete spiral), somewhat duplicating the twisted coil centre of the Archimedes Screw. Result - forward propulsion (instead of drawing water up a tube, it is sent behind us). I suspect it might be the same principle at work here. [/url]
An image that has had great appeal to me for many years - and which I referred in virtually every workshop I taught in the mid-90s - was that of 'augering' through the water like a drill bit into wood.

That image did lead us down a path we later abandoned - Single UnderSwitches, done to heighten the augering sensation.

We decided to stop teaching/using that drill because (1) it taught over-rotation which we had to undo later in the sequence, and (2) I gradually came to value effortless rhythms (Perpetual Motion Propulsion) over the drilling-through emphasis.

Nonetheless I still think the idea has some validity as an explanation, if applied effectively.
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  #17  
Old 02-03-2011
CoachSuzanne CoachSuzanne is offline
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Quote:
Originally Posted by terry View Post

But even to move past an anchored hand/arm, rather than use that hand to accelerate water back, we still rely on muscle to hold the arm in place.
When I am focusing on moving faster through the water, I feel that it takes even MORE muscular effort to anchor the arm without slipping...that it previously did to just pull harder through the water.
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  #18  
Old 02-03-2011
Thatchman Thatchman is offline
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Quote:
Originally Posted by CoachSuzanne View Post
When I am focusing on moving faster through the water, I feel that it takes even MORE muscular effort to anchor the arm without slipping...that it previously did to just pull harder through the water.
Hi Coach

Please could you explain to me the diff between anchoring the arm and moving past it and pulling with the arm.

Does this mean that we lock the arm and shoulder in position and use the rotation to bring it back as opposed to pulling it back

Reilly
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  #19  
Old 02-03-2011
haschu33 haschu33 is offline
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Quote:
Originally Posted by CoachSuzanne View Post
When I am focusing on moving faster through the water, I feel that it takes even MORE muscular effort to anchor the arm without slipping...that it previously did to just pull harder through the water.
Yes, I have the same feeling. Particularly that, it takes more muscular effort.

Otherwise I like the analogy of the screw. Although it lacks an important factor when looking at it more literally: where are the convolutions of the screw in our body? Without the convolutions the screw is just an axle and it doesn't give any propulsion when rotating. I think the same applies to our body. Whatever moves down on one side of the body moves up on the other side. I don't believe that the rotation as such provides propulsion. We need a bigger picture here.
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  #20  
Old 02-03-2011
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Here's my take on it: The front profile of our torso at the shoulder is wider than the side profile - essentially a contoured blade (or wing) shape. When we rotate, we displace water to the front facing and the back facing parts of our body. The "screw" comes in with our marionette arms and spearing, twisting the "body blade" from one side to the other.

Last edited by drone : 02-03-2011 at 06:53 PM.
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