GRV: Lavillenie - From Stall Swing to World Record

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canag
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby canag » Thu Mar 19, 2015 6:55 am

PVstudent, here are some more video sources of data from Prague's University:
https://www.youtube.com/channel/UC5B8gE ... h6wwEBX7_Q
I don't know which method they used for measuring the velocity, probably video analysis as I don't see any infrared timing gates, but the numbers seem reasonable.

Have fun! ;)

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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby PVstudent » Tue Mar 24, 2015 9:50 pm

Bearing in mind the following limitations of the video record:
1 Camera panning .

2 Estimating the pole length as recorded as being 5.20m in the lower right segment of the camera visual field and the natural flexing of the pole.

3 Assuming the pole is primarily located at right angles to the camera.

4 The camera location is not orthogonal (at 90 degrees perpendicular to the sagittal plane of motion) to the vaulter’s progression pathway but obliquely located with respect to the take-off point.

5 COM determination is subject to slight variable operator error, rounding errors and the constant errors involved in the XY body segment co-ordinate data processing to locate the COM on the images used.

6 Items 1 -5 above make the results presented below approximate as there are some small uncertainties in obtaining original xy co-ordinate measures.

The estimated parameters for Renaud Lavillenie’s 6.04m successful vault at the 2015 European Indoor Championships, Prague, 6-8th March are calculated by me as approximately:

1. COM Vertical Velocity 2.9 m/s

2. COM Horizontal Velocity 8.6 m/s

3. COM Resultant Velocity 9.1 m/s

4. COM Angle of Projection to Right Horizontal 18.4 degrees

I hope that the Charles University investigators will publish in due course their biomechanical analyses of the pole vault at these championships. I think my analysis despite the limitations will be confirmed as being reasonable and in agreement with their findings.

The Faculty of Athletics and Jan Feher of the Charles University are acknowledged as the publishers of the internet video recording used by me in making the above calculations.

Thank you to CANAG for directing me to this resource.

If electronic timing gates were not used I suspect that the average velocities shown on the videos could have been obtained with the LAVEG measuring system. The system is widely used throughout Europe in recording the run up speeds in the horizontal and pole vault jumps. LAVEG is also used in monitoring the 100m sprinting events.
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby willrieffer » Tue Oct 06, 2015 2:49 pm

Just to be clear.

In another thread grandvaulter posited that two vaulters of different heights would free swing at the same velocity. This is against well established principles of physics. They may indeed swing at the same speed (and where he used his eye to tell me they did), but not "freely". The natural movement of the shorter vaulter would be to progress faster through the angle...

It's here that we find that if we look at WC shorter vaulters like Lavillenie, Dial, Greg Duplantis, Jeff Buckingham, etc, you find they are all lead arm lockers. Why? Because they have to do so to stop swing progression where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed. This has almost NOTHING to do with force or pressure on the pole at the lead hand. Yes, it will feel like pressure and there MUST be an active/reactive force, but the important part of what it does is press or hold the COM back...which is part of the PB method! It was imperative to keep the COM/hips back! But of course, I'm wrong! LOL!

Again, this isn't a place where much, if any "science" is being done. It's a political argument.

When PV Student did his "box force" experiment and found a higher force by differing method it was extrapolated as being an infringement without taking every possible physics possibility into consideration. This is why he's more politician than scientist. A force at one end is going to end up at the other. SO the vaulter is going to experience higher pole braking which is the point at which he stopped his analysis because it offered the result he had set out to find the beginning(for any physicist this result such was so simplistic as to be given from a brief thought experiment!) . This COULD cause the vaulter to be thrown forward, which we all AGREE is a problem for both my ideas and the PB model. Yet it also means that the pole is taking on more energy, faster, bending more and shortening the chord faster which would, or can reduce its length and with all other things being equal, speed is rotation. But this idea was never addressed (neither has the "free" take off versus drive energy idea). Which is why we have a political argument and not a scientific one...and it continues. For the COM movement one would need to do a comparative study, not just post one graph (which would only be the scientific starting point) and then follow with a political argument. But its easier to be a politician with a gang than do good thorough science...

It took until I found a comparison of Bubka to Tarasov that things became somewhat clearer. Bubka as opposed to Tarasov would "hinge" the shoulder so that in the post take off the hips would follow the shoulders. This too, of course would keep the COM back. It does another thing as well, as its part of producing the high mid rate swing velocity of Bubka's vault which produces a centripetal accelerative force on the pole. Tarasov, for his part, tended to "look up" at take off and in the post take off we find his hips tilted "up" and working to lead the shoulders(If Tarasov was doing this, was he really even an actual PB method vaulter?). Lavillenie's method is to press the arm, drop the lead leg, and extend the trail leg, all things which move his COM back as well. Of course this keeps him from achieving Bubka's method. As he's "locked" he can't whip to a high angular velocity. SO what does he do? He pulls the legs up and pulls back under the pole. This ALSO creates an active/reactive moment on the pole. One can visibly witness this force in videos of these vaulters, in particular PV Students slo mo side by side. These are just vary different swing methods and patters...and both have been highly effective.

The question, which has not been answered in any significant way is this one. The PB model as proposed by its adherents assumes that it is THE most efficient method inclusive of all of its minor considerations independent of the vaulters particulars, notably size. My particular belief, for which I have provided evidence, and theoretical argument is that this particular idea should be viewed suspiciously. As I have proposed is that there are a lot of ideas and forms which have to be set to each other in evaluation and then mathematically analyzed, a lot of which takes DiffEq to do(where I've seen not one Differential Equation on this site). As example, to set Lavillenie's mid swing tuck/pull force against Bubka's centripetal accelerative one. But you know, that's hard and takes hard science. And it's complicated as PV Student points out by trying to equate vids with differing camera positions.

And "throwing the head back" would actually move the COM back in time IF all other things could be kept the same. But as any decent coach will know, in most cases where the vaulter would throw the head back they will also tend to throw the hips forward and then the vault into swing progression. But some athletes can do such. And so as much as anyone would want there to be a "rule" on such, vaulters are individuals of differing capabilities. It's pretty simple really, but hey, feel free to fall on your sword if ignorance again there gv...

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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby grandevaulter » Tue Oct 06, 2015 9:27 pm

willrieffer wrote:In another thread grandvaulter posited that two vaulters of different heights would free swing at the same velocity. This is against well established principles of physics. They may indeed swing at the same speed (and where he used his eye to tell me they did), but not "freely". The natural movement of the shorter vaulter would be to progress faster through the angle...

I stated that they moved at the same speed on different scales. I don't believe that my practical observation has been scientifically proven inaccurate. Give it a shot Will.

willrieffer wrote:It's pretty simple really, but hey, feel free to fall on your sword if ignorance again there gv...

I probably will fall on my sword after I trip over our two state championship trophies and one runner up in the last three years.

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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby PVstudent » Wed Oct 07, 2015 9:06 am

"It's here that we find that if we look at WC shorter vaulters like Lavillenie, Dial, Greg Duplantis, Jeff Buckingham, etc, you find they are all lead arm lockers. Why? Because they have to do so to stop swing progression where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed."

What does this actually mean?

Define lead arm-lockers.

“…where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed.”

It is very difficult to understand what the COM is doing if no axis for rotation is identified. Rotates forward? Do you intend the reader to understand that the COM is rotating, implying that it is actually spinning about an axis through the COM?

Or do you mean that whilst the COM is undergoing translation forwards in direction in the sagittal plane toward the landing pads it is also being simultaneously rotated about the pole tip transverse axis located in the planting box as well as being rotated in the opposite direction about the upper and lower grip transverse axes at the other end of the flexing pole due to the weight and swinging action of the vaulter?

“This has almost NOTHING to do with force or pressure on the pole at the lead hand. Yes, it will feel like pressure and there MUST be an active/reactive force, but the important part of what it does is press or hold the COM back...which is part of the PB method! It was imperative to keep the COM/hips back!”

Two points
1. Is holding the COM back actually espoused and advocated by either Petrov or Bubka?

I have had extensive contact with, coached alongside Petrov, have resided in Formia for extended periods whilst my vaulters (World Class level vaulters) were coached and trained in Formia by Petrov and accumulated comprehensive notes and video materials on the Petrov-Bubka Model of Pole Vault.

None of the experiences and learning at first hand from Vitali Petrov has revealed to me that he has ever advocated or insisted that the vaulter “… press or hold the COM back” which you claim / assert is part of the PB method.


2. The role of centripetal force is being misinterpreted by your claim referring to Messrs Lavillenie, Dial, Duplantis (Greg),Buckingham etc., when you make this assertion:

“It's here that we find that if we look at WC shorter vaulters like Lavillenie, Dial, Greg Duplantis, Jeff Buckingham, etc, you find they are all lead arm lockers. Why? Because they have to do so to stop swing progression where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed.”

My Comments for Consideration:

Since the vaulter is attached to the massive earth by the pole, centripetal force generated by the muscle work done by the vaulter in creating swing around both swing axes (namely Pole tip in the box and the grip axes) with the vaulter suspended below the grip axes, then vigorous swinging will provide an additional pole bending moment to that created by vaulter’s weight force.

By stopping or reducing the angular acceleration of the vaulter’s swing by “holding the COM back” the centripetal force contribution to the pole bending moments of force is removed or diminished. This has two undesirable consequences.

Consequence 1 reduction in pole chord angular velocity about the pole tip axis because there will be little or no angular momentum contribution from the vaulter swing as holding back is trying to create the same effect as a simple suspended “dead weight” below the hands. This negates some of the total system (Vaulter + Pole) angular momentum about the pole tip axis generated at take-off. Total system penetration rate towards the plane of the cross bar is thereby reduced.

Consequence 2 Retarding the vaulter’s swing acceleration and reducing centripetal force to keep the COM “lower” with respect to the pole tip axis increases or maintains the vaulter’s COM in a position relative to the grips that increases the moment of inertia about the hand grip pivots. The delay or pressing back of the COM increases the vaulter muscular torque required to initiate or create the swing angular velocity from a “dead hang” or “low rotational speed” about the grip pivots because of this larger moment of inertia about the grip axes.

The two consequences alluded to above get to the heart of the “Double Pendulum Challenge” that faces a pole vaulter once airborne in the first phase of vaulting.

All vaulters solve this “Double Pendulum Challenge” optimization problem in phase 1 of pole support to be successful in a pole vault jump clearance. What the optimal solution is can only be solved by a specific vaulter, in a specific vault attempt in a specific psychosocial-cultural and physical environment context.

The optimization requires multiple interacting parameters to be resolved.

These parameters involve both linear and nonlinear interactions in producing a desirable outcome.

Fortunately most vaulters employ an empirical learning of this optimizing process guided by their own efforts and input feedback from a coach.

Athlete and Coach use the tried and true “Suck It and See What is Just About Right!” method of Goldilocks.

This is doing in practice the “Arts” of pole vault learning and coaching. The practice process can be informed by science but it is not science!

The art can of course be studied and subjected to analysis using Newtonian Mechanics Principles by scientists and other people interested in the art of pole vault performance and coaching.

“When PV Student did his "box force" experiment and found a higher force by differing method it was extrapolated as being an infringement without taking every possible physics possibility into consideration. This is why he's more politician than scientist. A force at one end is going to end up at the other. SO the vaulter is going to experience higher pole braking which is the point at which he stopped his analysis because it offered the result he had set out to find the beginning(for any physicist this result such was so simplistic as to be given from a brief thought experiment!) . This COULD cause the vaulter to be thrown forward, which we all AGREE is a problem for both my ideas and the PB model. Yet it also means that the pole is taking on more energy, faster, bending more and shortening the chord faster which would, or can reduce its length and with all other things being equal, speed is rotation. But this idea was never addressed (neither has the "free" take off versus drive energy idea). Which is why we have a political argument and not a scientific one...and it continues. For the COM movement one would need to do a comparative study, not just post one graph (which would only be the scientific starting point) and then follow with a political argument. But its easier to be a politician with a gang than do good thorough science...”


This is not only inaccurate, misrepresenting what I have done in regard to measuring forces under the pole via transducers in the pole planting box but demonstrates yet again the correspondent’s inability to understand or communicate, or both, what I have actually stated.

The contributor’s attempted critique of my work, and that of others, does not convey in any cogent manner what it is that he finds so simplistic or wrong.

He is unable, as best as I can decipher from the above, to clearly and cogently describe where, when, what and why my contribution/s is/are or have been so simplistic and wrong.

If I’m wrong about something I will be the first to acknowledge my mistake/s when the mistake is clearly and explicitly explained to me. I am always ready and eager to learn.

The attempt to belittle with “This is why he’s more politician than scientist.” and “But it’s easier to be a politician with a gang than do good thorough science...” does not need any rebuttal from me!

I am not going anywhere near objects with sharp points or hoisting myself with my own petard and so, without any reluctance, relinquish my place at the discussion table.

I am happy to stay firmly grounded in the near enough is good enough Newtonian Earth World where basic mechanics principles operate quite well.

Bon Voyage Will on your trip through the nebulous “Black Hole” you are creating!
Last edited by PVstudent on Thu Oct 08, 2015 7:26 pm, edited 1 time in total.
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willrieffer
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby willrieffer » Wed Oct 07, 2015 12:10 pm

grandevaulter wrote:
willrieffer wrote:In another thread grandvaulter posited that two vaulters of different heights would free swing at the same velocity. This is against well established principles of physics. They may indeed swing at the same speed (and where he used his eye to tell me they did), but not "freely". The natural movement of the shorter vaulter would be to progress faster through the angle...

I stated that they moved at the same speed on different scales. I don't believe that my practical observation has been scientifically proven inaccurate. Give it a shot Will.

willrieffer wrote:It's pretty simple really, but hey, feel free to fall on your sword if ignorance again there gv...

I probably will fall on my sword after I trip over our two state championship trophies and one runner up in the last three years.


The problem is that you think there needs to be a "scientific" response to your practical observations. That's not how "science" works, or, you're working backwards. In this, the property of pendulums is proven science which YOUR observation goes against. OR, again, the point of proof is yours.

Indeed I say they CAN swing at the same speed, but only if they are actively regulating the swing speed.

Look, you want to keep advancing that the point is coaching versus physics in where you set coaching accomplishments against physics knowledge and methodology. It's not. It's physics versus physics where despite your coaching accomplishments, you're really really bad at physics.

Ya, ya. I have the #3 and #7 froshes in the state in all classes...

willrieffer
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby willrieffer » Wed Oct 07, 2015 12:44 pm

PVstudent wrote:"It's here that we find that if we look at WC shorter vaulters like Lavillenie, Dial, Greg Duplantis, Jeff Buckingham, etc, you find they are all lead arm lockers. Why? Because they have to do so to stop swing progression where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed."

What does this actually mean?

Define lead arm-lockers.

“…where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed.”

It is very difficult to understand what the COM is doing if no axis for rotation is identified. Rotates forward? Do you intend the reader to understand that the COM is rotating, implying that it is actually spinning about an axis through the COM?

Or do you mean that whilst the COM is undergoing translation forwards in direction in the sagittal plane toward the landing pads it is also being simultaneously rotated about the pole tip transverse axis located in the planting box as well as being rotated in the opposite direction about the upper and lower grip transverse axes at the other end of the flexing pole due to the weight and swinging action of the vaulter?

“This has almost NOTHING to do with force or pressure on the pole at the lead hand. Yes, it will feel like pressure and there MUST be an active/reactive force, but the important part of what it does is press or hold the COM back...which is part of the PB method! It was imperative to keep the COM/hips back!”

Two points
1. Is holding the COM back actually espoused and advocated by either Petrov or Bubka?

I have had extensive contact with, coached alongside Petrov, have resided in Formia for extended periods whilst my vaulters (World Class level vaulters) were coached and trained in Formia by Petrov and accumulated comprehensive notes and video materials on the Petrov-Bubka Model of Pole Vault.

None of the experiences and learning at first hand from Vitali Petrov has revealed to me that he has ever advocated or insisted that the vaulter “… press or hold the COM back” which you claim / assert is part of the PB method.


2. The role of centripetal force is being misinterpreted by your claim referring to Messrs Lavillenie, Dial, Duplantis (Greg),Buckingham etc., when you make this assertion:

“It's here that we find that if we look at WC shorter vaulters like Lavillenie, Dial, Greg Duplantis, Jeff Buckingham, etc, you find they are all lead arm lockers. Why? Because they have to do so to stop swing progression where swing progression is where the COM rotates forward lowering pole compression and causing the vault to fail or be infringed.”

My Comments for Consideration:

Since the vaulter is attached to the massive earth by the pole, centripetal force generated by the muscle work done by the vaulter in creating swing around both swing axes (namely Pole tip in the box and the grip axes) with the vaulter suspended below the grip axes vigorous swinging will provide additional pole bending moments to that created by vaulter’s weight force.

By stopping or reducing the angular acceleration of the vaulter’s swing by “holding the COM back” reduces the centripetal force contribution to the pole bending moments of force. This has two undesirable consequences.

Consequence 1 reduction in pole chord angular velocity about the pole tip axis because there will be little or no angular momentum contribution from the vaulter swing as holding back is trying to create the same effect as a simple suspended “dead weight” below the hands. This negates some of the total system (Vaulter + Pole) angular momentum about the pole tip axis generated at take-off. Total system penetration rate towards the plane of the cross bar is thereby reduced.

Consequence 2 Retarding the vaulter’s swing acceleration and reducing centripetal force to keep the COM “lower” with respect to the pole tip axis increases or maintains the vaulter’s COM in a position relative to the grips that increases the moment of inertia about the hand grip pivots. The delay or pressing back of the COM increases the vaulter muscular torque required to initiate or create the swing angular velocity from a “dead hang” or “low rotational speed” about the grip pivots because of this larger moment of inertia about the grip axes.

The two consequences alluded to above get to the heart of the “Double Pendulum Challenge” that faces a pole vaulter once airborne in the first phase of vaulting.

All vaulters solve this “Double Pendulum Challenge” optimization problem in phase 1 of pole support to be successful in a pole vault jump clearance. What the optimal solution is can only be solved by a specific vaulter, in a specific vault attempt in a specific psychosocial-cultural and physical environment context.

The optimization requires multiple interacting parameters to be resolved.

These parameters produce both linear and nonlinear interactions.

Fortunately most vaulters employ an empirical learning of this optimizing process guided by their own efforts and input feedback from a coach.

Athlete and Coach use the tried and true “Suck It and See What is Just About Right!” method of Goldilocks.

This is doing by practice in the “Arts” of pole vault learning and coaching. The practice process can be informed by science but it is not science!

The performance of the art can of course be studied and subjected to analysis using Newtonian Mechanics Principles by scientists.

“When PV Student did his "box force" experiment and found a higher force by differing method it was extrapolated as being an infringement without taking every possible physics possibility into consideration. This is why he's more politician than scientist. A force at one end is going to end up at the other. SO the vaulter is going to experience higher pole braking which is the point at which he stopped his analysis because it offered the result he had set out to find the beginning(for any physicist this result such was so simplistic as to be given from a brief thought experiment!) . This COULD cause the vaulter to be thrown forward, which we all AGREE is a problem for both my ideas and the PB model. Yet it also means that the pole is taking on more energy, faster, bending more and shortening the chord faster which would, or can reduce its length and with all other things being equal, speed is rotation. But this idea was never addressed (neither has the "free" take off versus drive energy idea). Which is why we have a political argument and not a scientific one...and it continues. For the COM movement one would need to do a comparative study, not just post one graph (which would only be the scientific starting point) and then follow with a political argument. But its easier to be a politician with a gang than do good thorough science...”


This is not only inaccurate, misrepresenting what I have done in regard to measuring forces under the pole via transducers in the pole planting box but demonstrates yet again the correspondent’s inability to understand or communicate, or both, what I have actually stated.

The contributor’s attempted critique of my work does not convey in any cogent manner what it is that he finds so simplistic.

He is unable, as best as I can decipher from the above, to clearly and cogently describe where, when, what and why my contribution/s is/are or have been so simplistic and wrong.

If I’m wrong about something I will be the first to acknowledge my mistake/s when the mistake is clearly and explicitly explained to me. I am always ready and eager to learn.

The attempt to belittle with “This is why he’s more politician than scientist.” and “But it’s easier to be a politician with a gang than do good thorough science...” does not need any rebuttal from me!

I am not going anywhere near objects with sharp points or hoisting myself with my own petard and so, without any reluctance, relinquish my place at the discussion table.

I am happy to stay firmly grounded in the near enough is good enough Newtonian Earth World where basic mechanics principles operate quite well.

Bon Voyage Will on your trip through the nebulous “Black Hole” you are creating!


It's just as someone that has studied and done science (The Ohio State University) I'm telling someone who's advanced that they haven't really studied physics or apparently the scientific method, you're a terrible "scientist". You critique my post with obfuscation. This has been the general rule, to try and NOT answer my dialog, but obfuscate and misconstrue it. This is actually pretty basic all along the way.

One thing that has been put forth at almost every point is that I don't actually fundamentally disagree with the PB Method in so much where it agrees with my own observations as a coach and my knowledge of science. Where Petrov said "watch the hips" with the idea of keeping them from being thrown forward under pole braking and offering a scientific explanation of why this is important. In the most simple way, I advocate that this is the important point and that outside of that the model is loaded with ephemera and bad science as explanatory of why it works and then lacking the real scientific explanation for why it works. Or, more simply put why Petrov was right in saying, "watch the hips" and keeping them "back" as they are the body part generally located closest to the COM post take off and this relation is fundamental to the gravity compressive moment and its effect on the pole. Lavellenie gets the same result but by different method. Against Tarasov who tilts his hips up in the post take off both Bubka and Lavillenie tip their hips down. This is the commonality, but they get to it in far different ways.

The sort of bad pseudo science which the responses and literature I've seen on the subject is actually something that happened with frequency in the old USSR. Crackpot science was allowed by hard core party "scientists" to ruinous results. In this I can theorize Petrov just copied Issacson's vault with a group of exceptional athletes and then "rationalised" it, generating the explanation for the results after the fact and without a good scientific base a description filled with poor science and holes. This again doesn't say it doesn't work, it says the scientific explanation is full of holes. Big ones. This is what I've shown. You want to flip the script, but you're the one with the ideal model and its minutia which is what needs defended and to be shown to be scientifically superior. At every turn it looks like you're not really up to the task. I mean this stuff about the PB is all proven right? You should be able to copy and paste what I'm looking for...but that stuff never shows up. Items which look like parts of it do and then sophistry to go with it. We get a graph that has no analysis. Still frame pics of what is ultimately a complex relation of curvilinear motion that necessitate differential math. It goes on and on...

I've explained all this before. The onus is on you to prove the ideality of the model in its minutia. I haven't seen one good response to that end...

Eh. Maybe I was just bored and felt like rattling a cage...

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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby PVstudent » Wed Oct 07, 2015 9:40 pm

Will,
If you are a trained scientist, your professional accomplishment in communicating in the written form about science and physics in particular does you no credit.

You may believe that you have communicated your understanding so that readers in the forum completely understand your points of view in regard to the physics of pole vaulting.

Whilst I am not a physicist and have stated so to this forum I find your contributions to be esoteric (Compliment) but unintelligible to me (Brickbat).

Whether a physicist could understand your written communication remains to be answered by a qualified physicist.

Your ideas may be as you believe them to be and that you clearly communicate top rate physical science analysis of pole vault in this forum.

It is with regret that I am one reader and discussant who finds your beliefs in what you think you have conveyed to readers somewhat lacking in "Scientific Credibility" to the point of immense frustration and deep suspicion as to your actual capacity and expertise in science ,especially physics.

You may be a Physicist, but you are not a particularly clear or articulate communicator on the subject matter of physics applied to the analysis of pole vault technique.

Mostly my frustration arises because when you do try to be "scientific" you throw around jargon terms derived from mathematics and physics without applying the methods and principles to which they refer in any of your analyses.

This is very unconvincing and raises much doubt in my mind as to whether you actually are as competent as you claim.

Will if you are bored and wishing to rattle some cages that is up to you. By doing this on the thread you started and continuing with "arcane esoteric and idiosyncratic interpretation of the basic physics of pole vault" (not a compliment) you are not being helpful and just clouding the issues you attempt to raise.

To be fair to you, I do admit there are occasional glimmers and shadows of perhaps sensible and correct physics interpretations in regard to pole vault technique that you attempt to make but that is all they are, confused and confusing thought bubbles.

You do not appear to me to be capable of bringing these ephemera into clear focus so that readers like myself can understand them.

I make no attempt to respond to your comments on Russian science applied to pole vault technique as they are completely irrelevant to the discussion and open to question as to accuracy from scientific, political and historical perspectives.
Last edited by PVstudent on Thu Oct 08, 2015 7:31 pm, edited 1 time in total.
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grandevaulter
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Location: South West, MI

Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby grandevaulter » Wed Oct 07, 2015 9:50 pm

willrieffer wrote:The problem is that you think there needs to be a "scientific" response to your practical observations. That's not how "science" works, or, you're working backwards. In this, the property of pendulums is proven science which YOUR observation goes against. OR, again, the point of proof is yours.

Indeed I say they CAN swing at the same speed, but only if they are actively regulating the swing speed.


Let's work backwards, you seem to think that's what works best for me. (first take a look at another one of your statements)
willrieffer wrote:In another thread grandvaulter posited that two vaulters of different heights would free swing at the same velocity. This is against well established principles of physics. They may indeed swing at the same speed (and where he used his eye to tell me they did), but not "freely". The natural movement of the shorter vaulter would be to progress faster through the angle...


Let's go through this "backwards" with a practical thinking coach. Perhaps a story problem:

A stickman comes to pole vault practice. He is an ordinary stickman, that acts like a pendulum. Well I guess he's not that ordinary, he's a one arm stickman pole vaulter. He comes to his coach, the coaches name is coach Strawman. Stickman asks coach Strawman what he should do today. Coach Strawman tells him to get back on the runway and jump from 8 lefts. He tells Stickman to swing his body perfectly straight. "Don't break at the hips, just swing like a pendulum, like the pendulum I saw on Willriefer's youtubes and cut and pastes".

Stickman runs up (very fast), plants and then swings his feet to inversion, 180 degrees from the earths plane on his one arm/hand axis. He totally resembles a pendulum. He asks coach Strawman; "Did my hips swing faster than my feet?" Coach Strawman says; "Idunno, I'm just a practical strawman coach" . Coach Strawman asks; "Did your hips reach 180 degrees before your feet, I can't tell, I just use visual observations, but WillRiefer thinks your hips traveled at a faster velocity because they are closer to the axis just like a short vaulter and your feet traveled at a slower velocity because they are farther away from the axis, similar to a tall vaulter, he claims the latter to be science".

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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby PVstudent » Thu Oct 08, 2015 5:20 am

Grandevaulter a funny, fatal riposte to Will. :D

I appreciate the sardonic humour and the point you make so well.

The instantaneous and the average angular velocity about the hand axis of Stickman's feet and hips will be the same in angular displacement magnitude!

The tangential or linear velocity of the feet and the hips of Stickman will not be the same because they are at different radius lengths from the axis about which Stickman inverts through 180 degrees.

Stickman's feet will have a larger tangential linear velocity magnitude due to their longer radial distance from the axis.

Since it is Stickman vaulting, linear velocity of his centre of mass will be of less magnitude but in the same direction as Stickman's feet at any instant of the inversion rotation about the hand axis because of it's shorter radial distance from the hand axis.

The curvilinear path followed by Stickman's hips (COM) due to Stickman rotating about his hand and the simultaneous rotation, bend and recoil of the pole about the axis at the pole tip that is occurring must also be considered. This must be done so that the rotation and translation motion of Stickman's hips, with respect to the pole tip axis in the box can be taken into account.

The 3-dimensional space curvilinear pathway (since the radial distance from the pole tip axis to Stickman's hips (COM) is not a constant radial length varying continuously with respect to time from Stickman's Take-off to 180 degrees of inversion) must also be taken into account.

It requires simple differential and integral calculus (when force transducers are involved in the data recording process) to resolve the resultant 3-dimensional space curvilinear path linear and angular kinematics and kinetics to precisely determine the actual path followed by Stickman's hips (COM) through 3-dimensional space.

( Reports in the scientific literature by researchers in America, Australia, China, France, Finland, Germany, Poland and Russia of which I am aware have used calculus based methods to perform this form of analysis from film, video, force transducer technologies used to record performance parameters in flexible pole vault. Will demonstrates that he is unaware of / unable to delve into / understand or translate this considerable reservoir of scientific investigative knowledge regarding the kinematics and kinetics of pole vault. Will would do well to use Google Scholar before making the gross generalisations in his so called critiques.)

Coach Strawman's pragmatism and experience shows him in "practice reality" that successful vaulting is accomplished when the Stickman's hips follow a curvilinear pathway in which the slope of the pathway increases rapidly following maximum pole bend. :star:

It also shows that prior to pole maximum bend the horizontal component (forward displacement) of the hips (COM) curvilinear pathway is LONGER than the vertical component (vertical displacement) per unit time.

The "Snap Buckling of the Pole" to the left (right handed vaulter) facilitates the continuation of the dominance of the forward horizontal displacement compared to the vertical rise displcement of Stickman's hips (COM) until maximum pole bend and for some short interval of time before the pole starts its recoil. :idea:

Coach Strawman's empirical observation, if accurate and reliable, will detect that the vertical component of the curvilinear pathway of Stickman's hips (COM) rapidly increases as the horizontal component diminishes after maximum pole bend. This change in ratio of the horizontal and vertical displacement distances travelled by the hips (COM) per unit time commences a short interval after maximum pole bend in successful vaults by elite male and female pole vaulters.

No need for differential calculus by Coach Strawman!. :crying:

Nothing new, unique or unknown. Nothing mysterious or difficult. Nothing that has not already been stated many times before by myself and others. :yes:

Grandevaulter is congratulated on demonstrating that "Will 'O the Wisp" merely throws straw into the wind to see which way the wind will blow! :dazed: :devil:
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby KirkB » Sat Oct 10, 2015 2:46 am

I am enjoying this debate between Will and PVStudent/GV. :yes:

GV, your stickman analogy is perfect, and I hope Will will provide a scientific response to it (skipping any personal barbs). In my eyes at least, science will prevail over flaming each other. :idea:
PVstudent wrote: The 3-dimensional space curvilinear pathway (since the radial distance from the pole tip axis to Stickman's hips (COM) is not a constant radial length varying continuously with respect to time from Stickman's Take-off to 180 degrees of inversion) must also be taken into account.

As I see it, a stickman moving down the plane of the runway, jumping into the air, and over the bar is a 2D analogy of the "real world" (3D) vault action. But other than the pole bending to the side of the 2D path (plane) taken by the vaulter, why complicate the analogy with the 3rd dimension? The issue of the motions of stickman's hips and feet can be fully explained within the confines of 2D (ignoring the 3rd dimension), can't it? :confused:

Take a crack at it, Will. Perhaps you have some good scientific basis for your points, but so far, you haven't explained them very scientifically. Put your money where your mouth is.

Keep in mind that I now believe (just this year, now that Lavillenie's and Barber's performances have opened my eyes) that Petrov may have overlooked the benefits of a lower COM (by dropping the lead knee). I note that Wolfgang Nordwig did this intentionally, and (on occasion, late in his career, and not by intent) so did Dave Roberts (and perhaps other WR setters). This suggests that I'm open to hearing the scientific reasoning behind this (which you may possess), but I haven't quite understood it yet.

I'm not at all convinced that bottom arm pushing or blocking is beneficial, but perhaps dropping the lead knee is related somehow to your "theory" or explanation of RL's alleged technical superiority (based on WRs) to Bubka's?

One further simplification to the one-armed stickman might (or might not) be in order. That is, suppose he's a one-legged/one-armed stickman. Will, if your theory is unrelated to the MOTION of the lead leg, then it can be simplified in the stickman analogy to be a single leg. But if your theory DOES take the lead leg's motion into account, then GV's one-armed/2-legged stickman is a better reference. Either way, let's hear it! :idea:

I'm looking forward to hearing some more good debate about this! :yes:

Kirk
Run. Plant. Jump. Stretch. Whip. Extend. Fly. Clear. There is no tuck! THERE IS NO DELAY!

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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby PVstudent » Tue Oct 13, 2015 9:03 pm

The fundamental premise amongst the many that have been made by WIll is not supported by the relatively recent evidence in Lavillenie's real world vaulting performances. The video below shows that he does not keep his COM (Vaulter's Centre of Mass) down and back in the pole support phases of the vault.

The pole support phases are defined as occurring between the instant ground take-off foot contact is broken until the instant the final hand grip in contact with the recoiling pole is released completely and the vaulter is airborne (free for indirect contact via the pole with the earth and subject only to air resistance and gravitational force causing a constant -9.81m/s/s acceleration on the vaulter vertically downwards).

https://youtu.be/sMpzTO8h5qk

I am unable at the moment to get picture files to upload to the message box to display the graphs I have made from an analysis of Lavillenie's vault at the French Indoor Championship in February 2015. :eek:

The graphs, I contend, will confirm that there is more than reasonable doubt that Will's theory has been founded on a fundamentally false premise if the evidence above is accepted by the jury of PVP readers. Advanced coaches and vaulters I hope will be able to make their assessments and adapt their practices according to evidence and results from the real world experiences of elite pole vaulting.

If any reader can help me to get the PVP attachment mechanism to work I will be able to provide further evidence to substantiate my information and clarify some of the facts as opposed to highly dubious thought experiments and conjectural conclusions that has riddled the latter part of this thread. :confused:
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