How much extra propulsion does optimal roll deliver?

[Zenturtle]

didnt read copy paste for beginners....

http://www.swimmingworldmagazine.com/ne ... -triumphs/

If you focusl on it, its pretty clear that the connection with the bodyroll and arm movenet is strongest at the start and the end of the stroke, what is completley logical from the propulsive surface angle point of view.

Anybody can try this.
Float in prone position and test in 3 arm positions while someone rotates the body plus and minus 45 degrees.
-1 Arm in normal catch position
-2 Arm at shoulder height (90 degrees through armstroke). propulsive plane facing perfectly backwards
- 3 Arm at 135 degrees through armstroke, a bit before exit point.

Only in position 2 the bodyroll is free and not connected with the arm.
IN the other positions you wiill feel pressure on the forearm (and hand depending on hand angle.)
If fingers are pointed to the bottom of the pool at position 1 en 3, the hand surface is also disconnected with the roll in those positions.
Thats what Rod means. He is the hand force man.
A guy like Sun Yang also doesnt feel pressure on rotation in position 1 on the forearm caused by simple body rotation. His forearm is vertical in position 1.
Most normal people will feel pressure caused by rotation in this test in position 1 and 3.

If a human arm couild move like a conveyer belt, it would be possible to keep the propulsive surfaces perpedicular to the swim axis.(Rod is 100% right)
If a human arm windmills underwater, only at 90 degrees this condition applies.(Rod is 5% right)
The real movement is somewhere between those 2 extremes.

[CoachDavidShen]

Originally Posted by Zenturtle

didnt read copy paste for beginners....

http://www.swimmingworldmagazine.com/ne ... -triumphs/

hey zenturtle, sorry this link also doesn't work! i think the forum software is truncating it in a bad way. can you use the link icon (little globe with 2 chain links) and link some text with the URL of the video?

[Zenturtle]

http://www.swimmingworldmagazine.com...free-triumphs/


yeahhhh

The girl in lane 1 is relying more on arm strength, but she gets passed before the finish. Look how the girl in lane 2 throws in her whole body twist right before finishing.
The same basics in my preposed dryland arm windmilliig awareness exercise.

[CoachDavidShen]

Originally Posted by Zenturtle

http://www.swimmingworldmagazine.com...free-triumphs/


yeahhhh

The girl in lane 1 is relying more on arm strength, but she gets passed before the finish. Look how the girl in lane 2 throws in her whole body twist right before finishing.
The same basics in my preposed dryland arm windmilliig awareness exercise.

i was impressed with girl in lane 1. she has a very TI stroke from my view, and was very close to the leader for a long time. but i think that she got tired and/or made a tactical mistake in that she should have increased stroke rate on the last 1-2 lengths.

girl in lane 2 (from the camera) has a classic sprinter stroke, very little patient lead arm, with arms 180 deg to each other. i must admit i admired her ability to hold on like that for 400m. but she falls behind as she spears directly into catch which lowers her apparent body length already.

ultimately i'm not good at looking at fast swimmers' videos. i like to download and play in slow-mo.

still, i don't know if this has been talked about yet - but aren't you talking about the propeller concept in propulsion? see diagram 3 here:

http://coachsci.sdsu.edu/swim/bullets/forces3.htm

[Zenturtle]

Difficult to explain what is so obvious in your own mind.

I wanted to show this because it shows how the body is very clearly working together with the armpull.
Its what Terry said " There are a lot of muscles between your toe and your hand" or something like that. And I believed he meant that all those muscles should work in synchronised manner for optimal propulson.
She is showing exactly that, only at about double the strokerate the avarage TI guy is swimming. I believe this is whats makes it possible for the girl with the scrappy stroke to keep up , and even pass a lot of girls with better looking strokes. Nowedays its believed 6BK is the future, but a proper 2BK mechanism has a certain charm and efficiency.
The high strokerate means she also has to handle the rotation inertia, but thats another story. Little time here to keep the hand outstretched, also a different chapter.Well, the very fast catch may be linked to her fast 2BK, she is the only one with this catch and this 100% 2BK. So one part is very TI like, adaptions to the high strokerate are not. As long as most part of the arm is moving back faster than the body is moving forward that part is not creating drag , but propulsion. She is not making a longer vessel, thats right, but what are the exact positive numbers proving how much is gained by elongating the vessel temporarely?

I am not talking about propellors in the sense that is meant in your article.
I am only saying that for the vast majority of swimmers that cant make the ideal perfect armstroke with vertical propelling planes from entry to exit, the bodyroll has an influence on propulsion.

another example.
Imagine you are standing in the shallow part of the pool. Before you lies a 80 kg treelog floating in the water.They have made arm like rods on the treelog with adjustable paddles.
If you turn the paddlesurface in the direction of the centerline of the treelog (surface resisting forward movement) and the treelog is rotated, the water is flowing along the surface of the paddle. There is zero drag. No resistance when the treelog is rotated.
Now turn the paddleblade 90 degrees and the surface of the paddle is facing toward the bottom of the pool(in swimming comparable with arm entry parellel with the water surface). There is maximum resistance on rotation, minimal resistance when pushing the treelog forward.
Now turn the paddle blade 45 degrees and there is resistance in the turning direction, and resistance in the forward direction.
Rotating the treelog results in a corkscrewlike path through the water. Rotation is linked with propulsion.
You could see this as a propeller action, but its not the propellor action normally meant by talking about the old fashioned S pull.
I cannot keep the foream and hand vertical during the total armstroke, so when I am holding them under an angle and rotate at the same time, you get the same effect as the treelog with the paddle under an angle.
Rotation has an influence on propulsion.

Conclusion from this (fact in my eyes) is that a driven rotation can produce propulsion. The 2BK twisting body swimming style from the clip show how the legs create an anchor for the armpull and drive rotation at the same time.
Thats how it looks to me. Charles doesnt agree with this I believe because the girl probably can swim just as fast without the leg kick, but with a pull buoy that keep the legs at the same height.
Maybe because she saves a lot of energy that way that can partially be used on the arm movement, and the basic core action is kept the same at a lower effort level and almost zero leg amplitude.
i dont know. Just chatting here.
If anybody has any ideas about it, join the chat.

[CharlesCouturier]

Originally Posted by CoachDavidShen

i was impressed with girl in lane 1. she has a very TI stroke from my view, and was very close to the leader for a long time. but i think that she got tired and/or made a tactical mistake in that she should have increased stroke rate on the last 1-2 lengths.

Not sure if you tried this and was successful with this strategy, but as far as I'm concerned, once the muscles which are responsible for keeping good form are tired, it's over. Increasing the rate translates into lowering the spl, and the speed doesn't increase.

Upping the rate as a tactical way of achieving for instance, a negative split over a distance only works as long as you can keep the spl stable (i.e., not loose some at any point), which implies to bet on the right spl/rate ratio right from the start.

Originally Posted by Zenturtle

Conclusion from this (fact in my eyes) is that a driven rotation can produce propulsion. The 2BK twisting body swimming style from the clip show how the legs create an anchor for the armpull and drive rotation at the same time.
Thats how it looks to me. Charles doesnt agree with this I believe because the girl probably can swim just as fast without the leg kick, but with a pull buoy that keep the legs at the same height.

hahaha, you know me too much by now. I was about to bite on this. Think inside out, at least if you want to better understand how these elites swim. And you're right, most if not all of them are very comfortable swimming almost as fast (if not faster for some) with a pull buoy, which, in my opinion, throws down any theory relying on the kick as an anchor point. It's very simple.

[sclim]

Originally Posted by CharlesCouturier

hahaha, you know me too much by now. I was about to bite on this. Think inside out, at least if you want to better understand how these elites swim. And you're right, most if not all of them are very comfortable swimming almost as fast (if not faster for some) with a pull buoy, which, in my opinion, throws down any theory relying on the kick as an anchor point. It's very simple.

So, in your analysis, because the elites can swim as fast or faster with a pull buoy, that means the kick is not an anchor point. OK, then what does the kick do then? Is it only a device to get the legs out of the drag zone? Aren't they using up a lot of power to do this (i.e. all that power for net velocity contribution of zero), and couldn't they figure out a more efficient way of getting their legs out of the way?

[Zenturtle]

Yeah Charles, I can understand people are just as fast with a pull, but dont you agree that at least there has to be sone body tension through the core to the leg that resembles the kick action, but only in a static way? So the leg doesnt move, but is kept connected with the pull?
That feels for me the most efficient foundation for the pulling action.
Could be doing something wrong off course...

[CoachDavidShen]

Originally Posted by CharlesCouturier

Not sure if you tried this and was successful with this strategy, but as far as I'm concerned, once the muscles which are responsible for keeping good form are tired, it's over. Increasing the rate translates into lowering the spl, and the speed doesn't increase.

Upping the rate as a tactical way of achieving for instance, a negative split over a distance only works as long as you can keep the spl stable (i.e., not loose some at any point), which implies to bet on the right spl/rate ratio right from the start.

actually we agree. that's why i put an "and/or" in between the two choices. you're right - once form is done because of fatigue, stroking faster isn't going to help. you'll probably even slow down.

[CharlesCouturier]

Originally Posted by Zenturtle

Yeah Charles, I can understand people are just as fast with a pull, but dont you agree that at least there has to be sone body tension through the core to the leg that resembles the kick action, but only in a static way? So the leg doesnt move, but is kept connected with the pull?
That feels for me the most efficient foundation for the pulling action.
Could be doing something wrong off course...

Your statement makes sense, in that it's difficult to dispute. Because yes in some regard, if the pull floats, then some force can be applied against it. So at that level, I can't disagree, since I certainly can't claim being right about these things

Originally Posted by CoachDavidShen

actually we agree. that's why i put an "and/or" in between the two choices. you're right - once form is done because of fatigue, stroking faster isn't going to help. you'll probably even slow down.

I am glad then. Because right there in this choice a swimmer must make, lies the truth (on optimal sr/sl). The SPL must be constant (or almost) throughout the event/test trial, to claim having found the right combination.