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  #1  
Old 11-04-2015
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Default The Propulsion Paradox

A fascinating piece from Science Editor, Sara Knapton, Telegraph UK: "For nearly 100 years, it has been assumed that mimicking natural swimming meant finding ways to generate high pressures. Now we realize we've had it backward": Could humans swim quicker by imitating eels and jellyfish?.

This falls on the heels of a recent blog from Terry: Swimming Principle #2: Most of what we know [or have accepted] about swimming is wrong!.

Also an interesting video from Coach Boomer, "throwing recovery arm (or high side) weight forward connected to pelvis generating (forward) momentum in its rhythm cycle and space": Freestyle Re-imagined

Enjoy!

Stuart
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  #2  
Old 11-04-2015
Zenturtle Zenturtle is offline
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To my knowledge you only can create a low pressure region in a swimming movement by creating a high pressure region somewhere else.
You could also say that the low pressure region in front of the underwaterarm is sucking the swimmer forward, instead of the pressure on the rear side is pushing the swimmer forward.

What about this swimmers throwing the arm weight forward and connecting everything? (when she gets in her optimal rhythm)
https://www.youtube.com/watch?v=M6YoMgYTXco

Last edited by Zenturtle : 11-04-2015 at 10:20 PM.
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Old 11-04-2015
tony0000 tony0000 is offline
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I'm all for undulation, but let's remember that throwing the arm forward requires pushing the rest of the body backward. (For every action, there's an equal and opposite one.)

Tony

"Swim by the mile; improve by the inch."
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Old 11-04-2015
Zenturtle Zenturtle is offline
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The arm can be thrown forward because the other arm is holding water and acts as a foundation.
The underwater arm makes the whole action like a ratchet mechanism.
Without it the body would decellerate when the arm over the top accelerates forward in the first half, and accellerates again when the over the top arm decellerates in the second 90 degrees.
The nett effect would be zero without the anchored underwater arm.
If the underwaterarm would be totally static relative to the body it would just act as a movement damper, damping the body movement from the waving arm on top of the body.
The ratchet works best when the resistance of the underwaterarm is highest when the above arm is accelerated, using the foundation of the underwaterarm, and the arm is in a more streamlined position when the upperarm decellerates, taking the body forward in the action+reaction cycle.
Thats basically a kayak arm timing, the opposite from catchup.
These arm throwing swimmers often move more toward kayak timing compared to the lineair high elbow swimmers like Mack Horton.
Thats also the case in the above posted video example.

If loping has some undulation in it, these swimmers already perhaps have found out some of this jellyfish stuff.
Often coaches learn form the very best swimmers and a little bit the other way around

Last edited by Zenturtle : 11-05-2015 at 06:55 AM.
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Old 11-05-2015
tomoy tomoy is offline
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Kind of wondering if someone will invent a new form of swimming. I imagine it would be some rolling or twisting version of an underwater dolphin kick which would rotate the mouth to air. Or maybe very dolphin like with several kicks on the back, surfacing to air, then diving back deeper for propulsion. Humans are just built wrong... or need bigger lungs.

Disruption in the water - maybe it's time : https://en.wikipedia.org/wiki/Fosbury_Flop

:-)
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Old 11-05-2015
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I love paradox - it removes long lasting filters and broadens your view. Research is beginning to show we've had it all wrong even with aquatic creatures too, largely due to looking through the human lens of vessels that operate on terra firma where we spend the majority of our life. Although I don't think a new stroke will appear anytime soon at meets or open water swims, i.e. the "Eel". What it does tell us is locomotion is not necessarily generated from pushing water back.

Paying attention to how Boomer describes the recovery arm momentum swinging forward connected to pelvis for propulsion is fascinating, and I dare say, very forward thinking. Paraphrasing Coach Boomer: "The bottom side (arm in the water) creates a platform beyond which the body can slide. Initially or instinctively we use the bottom arm as an impulse generator to move water backwards; when you move water backwards you do not move forward very well. The purpose of the bottom arm is to create thick water to hold as you throw recovery arm weight in front of it (the bottom arm)".

Coach Boomer is (and has been) removing filters of conventional wisdom, looking at swimming from a completely different lens, or better, a far bigger lens. Aquatic creatures creating vacuum or suction from lateral low pressure zones for locomotion - who would have ever thought? Science - great stuff.

Stuart
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Old 11-10-2015
terry terry is offline
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Quote:
Originally Posted by CoachStuartMcDougal View Post
Also an interesting video from Coach Boomer, "throwing recovery arm (or high side) weight forward connected to pelvis generating (forward) momentum in its rhythm cycle and space": Freestyle Re-imagined
I'm coming to this a little late. I have to say I see many flaws in the drill illustrated on this video
1) Over-rotation to a stacked position.
2) Arms crossing to centerline.
Both of these hurt core-stability
3) The circling-overhead recovery arm.
This significantly reduces connection of weight shift to arm stroke. It also looks like an injury waiting to happen.

Finally, the long kicking-glides hurt, not help, rhythm.
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Old 11-10-2015
fooboo fooboo is offline
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Quote:
Originally Posted by terry View Post
I have to say I see many flaws in the drill illustrated on this video
1) Over-rotation to a stacked position.
2) Arms crossing to centerline.
Both of these hurt core-stability
3) The circling-overhead recovery arm.
This significantly reduces connection of weight shift to arm stroke. It also looks like an injury waiting to happen.
Finally, the long kicking-glides hurt, not help, rhythm.
All correct. Best bet is that Boomer exaggerated moves to show
them properly.
After seeing the video again, I fancy if that recovery arm makes
not circling, but linear move to fulfill the task? Swimmer really, really
throws. He cannot do it, but in linear way. Am I wrong or K. Ledecky
already swam Boomer style? With above mentioned complaints taken.
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Old 11-10-2015
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Hi Terry, fooboo,

Yes, agree on 1, 2, and 3 especially in drill. But when swimmer "Sam" transitions into whole stroke he begins to flatten out and strikes wider on shoulder width tracks. But as I noted with Coach Eric earlier is to remove our current filters and listen to the message and language used, not necessarily what we see is immediately or obviously wrong (or right) from a teaser video.

The message is how momentum of the recovery connected to hip (pelvis) pulls the swimmer down the pool, *not* from pushing water back. The focus on starting the stroke at recovery helps remove the impulse or instinct to pull the arm back. The pulling impulse is easy to spot (as you know too) - once pulling hand/arm exits water, the "hand flip/flick" happens due to hand moving from water to air, sending it over the hip triggering elbow creep and lift over torso (not swing out), and a decelerating hitch at hip. One of my pet peeves observing lap swimmers.

Coach Boomer carefully uses language of "ride the space in front", "slide forward", increase distance per cycle - he avoids using "glide" which is what is happening. Clearly, the word "glide" has been overloaded and butchered by others to the point of creating a negative connotation as if "glide" is some kind of a dirty word that causes deceleration. We all know it's neither the glide nor the arm anchored in front that causes deceleration, it's the "shape of the vessel" breaking down from pulling and kicking impulses, swimming from the outside-in.

We (TI) are essentially delivering the same message, core-driven, inside-out whole body movement driven forward, forward thinking (pun intended), but Boomer is using a different language and perspective. I'm not suggesting we use Boomer's language or drill, it's only another perspective to explain/support the "propulsion paradox" - propulsion is not necessarily generated from pushing water back, and now observation and research is beginning to prove that accepted theory is quite narrow and incomplete.

Stuart
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  #10  
Old 11-10-2015
Danny Danny is offline
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I agree with Terry on this, for whatever it's worth. I understand that some theoretical points are being made with this drill, but swimming is a series of compromises between what we would like to do, because it is efficient, and what our anatomy will let us do.

If you recover with an extended arm (no bend at the elbow) your hand will have a lot more rotational inertia because it is further from your body. If this extended hand is not directly over the body (with stacked shoulders), but instead going out to the side somewhat, it will torque the body out of position, which hurts streamlining. So it is no surprise that Sam is swimming with stacked shoulders.

Stuart, you mentioned that, when he starts swimming full stroke, his body is flatter than in the drill, but his arm is still going pretty vertical to avoid torquing (and also to use forward momentum instead of sidewards momentum). The other person who recovers like this is Shelly Ripple, and she has a beautiful stroke. That said, you need very good shoulder flexibility to be able to swim like this. I tried it, and quickly discovered that it hurts my right shoulder (which is my bad one). By recovering with a bent elbow, you reduce that rotational inertia, and it makes it a lot easier on the shoulder. As far as using forward momentum, is this throwing the baby out with the bath water (pun intended)? Maybe, but to those who want to take advantage of this type of forward momentum, a word of caution may be in order. As Terry says, it looks like a shoulder injury waiting to happen.
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