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Old 01-31-2011
Lawrence Lawrence is offline
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Default How does weight shift cause propulsion?

If 'weight shift' means the strategic use of gravity rather than muscular effort, and gravity pulls downwards, how can it be used to propel you forwards?

There may be several parts to the answer. Perhaps we could start with the main ones.
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Old 02-01-2011
Grant Grant is offline
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Originally Posted by Lawrence View Post
If 'weight shift' means the strategic use of gravity rather than muscular effort, and gravity pulls downwards, how can it be used to propel you forwards?

There may be several parts to the answer. Perhaps we could start with the main ones.
Alott of you folks think these issues in much greater detail than I do and I appreciate it because it streaches my mind. Will say my little piece and then watch for the in depth stuff.
Gravity for sure pulls downward. The high hip moving downward is taking advantage of gravity so it is easier (less Muscle used). What I have found if I move my hip foreward as well as downward I get a much better result with the following spear and catch. Years ago someone asked what muscle is used to move the hip forward and I still dont have the answer. Perhaps the Physio's can enlighten.
I know that dosn't answer your question, rather it points out another small item in the chain of events that results in forward propulsion.
Have at it folks.
May we swim with ease at the speeds we choose.
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Last edited by Grant : 02-01-2011 at 12:51 AM.
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Old 02-01-2011
borate borate is offline
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If 'weight shift' means the strategic use of gravity rather than muscular effort, and gravity pulls downwards, how can it be used to propel you forwards?
A recent PBS NOVA program featured a segment on the properties of bodies propelling through two liquids.
In an image taken straight from your high school biology class, the tail of a sperm-like creature oscillated up and down with vigor as it swam through plain water.

Their experiment proved that as the liquid became more viscous an up/down tail movement would not be sufficient to generate propulsion. Dead in the water.
Yet this microscopic creature continued to advance through that medium. How could that be?

When the sperm-like body was viewed at higher magnification the answer became apparent. The tail was not oscillating up and down. It was a corkscrew!
And that strikes me intuitively as the reason behind the forward momentum being discussed here...

Rather than dissecting the elements of the stroke, envision them as acting SYNERGISTICALLY. Correctly timed, it's a beautiful thing...
The kick/hip drive twists the body at nearly the same moment as the arms spear and pull respectively. This may 'screw' the body forward.

Last edited by borate : 02-01-2011 at 11:06 PM.
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Old 02-01-2011
CoachKevin CoachKevin is offline
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Originally Posted by Grant View Post
Gravity for sure pulls downward. The high hip moving downward is taking advantage of gravity so it is easier (less Muscle used). What I have found if I move my hip foreward as well as downward I get a much better result with the following spear and catch. Years ago someone asked what muscle is used to move the hip forward and I still dont have the answer. Perhaps the Physio's can enlighten.
Grant, I don't think you can actually move your hip forward by itself. Your hip would move forward because it's attached to something else - your arm? - that moves forward. A well timed kick would get it all started. These "connections" that make your swimming "tick" are what work the magic. The kick is connected to your rotation & your rotation is connected to your spearing arm.
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Old 02-01-2011
CoachKevin CoachKevin is offline
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When the sperm-like body was viewed at higher magnification from behind the answer became apparent. The tail was not oscillating up and down. It was a corkscrew!
And that strikes me intuitively as the reason behind the forward momentum being discussed here... Rather than dissecting the elements of the stroke, envision them as acting SYNERGISTICALLY...
The kick/hip drive twists the body at nearly the same moment as the arms spear and pull respectively. This may 'screw' the body forward. Correctly timed, it's a beautiful thing.
That's right, borate. That's the Kinetic Chain I mentioned before - kick... then rotate... then lengthen. The rotating body doesn't - can't, really - propel itself, but in conjunction with the correctly timed kick & lengthening movements propulsion happens. And timing is everything. A swimmer can do all 3 things correctly, but done with the wrong timing it doesn't work, at least not as well as it could. We taught 1000's of people to just rotate & lengthen before we started to teach (2 beat) kick timing back around 2004 or so.
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Old 02-01-2011
CoachKevin CoachKevin is offline
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If 'weight shift' means the strategic use of gravity rather than muscular effort, and gravity pulls downwards, how can it be used to propel you forwards? There may be several parts to the answer. Perhaps we could start with the main ones.
Lawrence, why do think that no muscular "effort" is used to rotate?
I would say that gravity & muscles have to work in concert to facilitate rotation.
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Old 02-01-2011
Grant Grant is offline
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Grant, I don't think you can actually move your hip forward by itself. Your hip would move forward because it's attached to something else - your arm? - that moves forward.
Thanks Kevin, you have got me thinking. When I get back to the pool I will investigate this.
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Old 02-01-2011
Lawrence Lawrence is offline
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Kevin, as I understand matters, both muscles and gravity are used to generate propulsion. The muscles part is relatively easy to understand (e.g. muscles are used to hold/move the catching hand and arm against the water). It's the 'free' propulsion derived from the exploitation of gravity that I'm asking about. Doubtless that element and muscular effort are closely intertwined, but that doesn't mean they are the same thing.

I suspect it comes down to using gravity to cause certain body parts to move against the water at an angle, but will hold off going further until others have had their say.

Last edited by Lawrence : 02-01-2011 at 10:01 AM.
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Old 02-01-2011
terry terry is offline
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What I have found if I move my hip foreward as well as downward I get a much better result with the following spear and catch.
I don't know what muscle moves the hip forward, but haven't really been curious about that. I'm not sure it's only a muscle that does. I believe the extension of one side of the body toward the target plays a large role - which means many muscles move the hip forward.

But I was told by TI-AUS Coach Pat Baker, who is also a PT with 30 yrs experience, that the pelvis does move in that direction. This came after I gave her that precise instruction. Move your hip forward, not just down.

As to how we move forward with weight shift, it seems pretty evident to me that anchoring the hand and forearm at our foremost point allows it. Similar to running. Or x-c skiing. We plant a foot, shift our weight to the other side and move past our foot-plant.
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Old 02-01-2011
terry terry is offline
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I would say that gravity & muscles have to work in concert to facilitate rotation.
Clearly true. Muscles do contract, after all, even if to stabilize. 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.

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.
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