GRV: Lavillenie - From Stall Swing to World Record

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

Unread postby willrieffer » Mon Jan 26, 2015 11:15 am

willrieffer wrote: So you might get a case where the methodology worked, but for reasons other than the ones stated. Or that the stresses on the particulars might be out of sync with the physics explanation.


KirkB wrote:When a vaulter executes a vault, he usually does so with some cognizant INTENT to use the Laws of Physics to his advantage. But sometimes, HAPPENSTANCE happens, and sometimes INTUITION happens. In either case, the vaulter (and/or his coach) may not fully understand why something that they just did worked well, but it still follows the Laws of Physics EXACTLY. This has personally happened to me on a few occasions.

Happenstance is basically a coincidence that (in the context of this discussion) just happens to be a combination of GOOD things that happened during a vault.

And intuition is basically a good combination of things that happened not because the vaulter intentionally did them on THAT particular vault, but because his training regimen caused his muscle memory to react in a rather automatic way. A couple good examples of this are the way Kjell Isaakson was so vague about how he swung ("I just jumped"), and the way Bubka described the details of how he swung ("Arrrrgh"). This is the reason that I encourage highbar work so much.

I don't mean to be defending Will too much here, as I probably disagree with more than half his "scientific" assertions. However, his alternate, minority view has opened my eyes wider than they were open before.

Kirk


I can use, for example, the idea that the method is concerned about losing energy in the box. According to the laws of physics, of conservation of energy, because during the vault the box doesn't move, there can be no great loss of energy. IF the box cannot be a major source of energy loss to be concerned about, what is the concern with this idea about? IS is simply something that is a useless boondoggle of their method? Or is it something else? I think it is something else...

I will say I do have to guess here a bit on this. But I think its a good guess.

In building a worry about a loss of energy in the box it creates in the mind of the vaulter an idea and approach to elevate the take off. That if they come in low and initiate a low take off trajectory "into the box", they will "lose energy" into the box. The idea that the vaulter needs to elevate into the pole to induce pole rotation about the tip is certainly worthwhile. It leads to a better vault. That it needs to be done otherwise compared to other vaulters a lot of energy will be "lost in the box" in a magnitude negatively impacting the vault is just flat out wrong.

So again, the whole of the methodology in intent causes the vaulter to elevate into pole rotation. But the physics explanation points to an idea that just cannot be. The box doesn't move during the vault in any appreciable way. It's not a real source of energy loss. It acts the same for all vaulters. There is a little bit of energy lost there due to pole tip friction, but it is going to be very close to being the same for all vaulters, and of many magnitudes less than some other considerations. And so from a purely physics standpoint "box energy loss" is something not to be worried about at all. But from a vaulter intent standpoint? Apparently it was a very useful psychological tool for coaches in the PB model and so matters a lot. I have been working here to try and pull these things apart. The useful "myths" that impart useful intent into the mind of the vaulter in their approach, from a real physics based explanation of events.

The method is littered with stuff like this. In some sense the free take off crumbles when normal take off variance is accounted for (Bubka's own take off variance admissions coupled with Bubka's monster '93 worlds attempts coming from pole bend take offs), but for any coach there must be a goal. An idealized take off point and method. That Petrov stressed the motion of the hips is where I fall into agreement with the model and where I put the stress. It is the most important point. To them to keep them back in time, or for me to push them back in time, is the most important aspect of the vault, and I have attempted to use physics to explain why. It makes better use of the gravity vector on the pole in time. It is here where I stress it over take off methodology. And it isn't that the "free" PB model take off methodology is wrong. But it is as I say, "posture over placement". It is better to be under and be able to keep the hips back ( as with Dossevi) than it is to be on the ideal take off mark but then allow the hips to be thrown forward under pole brake( free hips model which was eclipsed by the PB model). Lavillenie, I believe, executes this type of vault and shows us its value in efficiency. He shows that his activities in keeping his COM as far back and down by his use of the front arm, the lead leg drop, and trail leg posterior motion, and then tuck to get out, coupled with his use of the "free" take off, which has generated the most efficient vault form in history. We know this because the facts of his shorter stature and rather typical footspeed for a WC vaulter make it more challenging for him to enact the sorts of all time WC jumps he has made. He makes up for it in his swing efficiency and post take off pole relations.

Will

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

Unread postby grandevaulter » Thu Jan 29, 2015 7:39 pm

https://www.youtube.com/watch?v=-TWAbc5TdpM
http://youtu.be/r9s3I2FuOaQ
https://www.youtube.com/watch?v=r9s3I2FuOaQ

Will,
I guess the coaches from these no tuck female vaulters missed the NASA paragraph. But your scientific analysis is so compelling, you may still get a call from them. You have conceded the free take off but haven't addressed the pre jump take off. Two of the three use the pre jump.

willrieffer wrote:I get it. There a lot of emotions involved in this, at least on one side. Much of all that is unfortunate.

The unfortunates, that I took the time to read your posts and cheap shots at Altius. Nothing emotional about that.

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

Unread postby PVDaddy » Sat Jan 31, 2015 12:42 am

Stopped in just to see were this all has gone. I am sorry to hear that Altius has passed. I did not have the time or energy to read through all of PV Students mindless scientific charts and dribble. I read enough to see that he is back peddling now and he even admits that lavellenies technique is not fully Bubka. Now he says the swing is not the same and he is FINALLY looking at Pole Rotation. Just wanted to remind all you experts what I had concluded and posted here almost a year ago and when the dust has finally settled this is where you will finally arrive. The two major secrets to Lavellenies success and what he does better than Bubka are the following.

1. He looses very little braking energy when he transfers his run up energy to his take off by attempting to jump up or drive the lead leg hard. He also extend s his bottom hand early and more full than Bubka which keeps him further back and lower.This also insures that he has a very low cog immediately going into his swing. In fact he insures and Maintains that low Cog by actually lowering his drive knee. This allows him to achieve maximum catapolitic effect into his swing and transfer of energy into his swing and the pole, but equally important enhances the proper pole rotation.

2. From the beginning and throughout his swing he does everything to ensure the Natural elemental rotation of the pole. He does not fight it at all and Bubka does more early in his swing. Lavellenie also opens his bottom hand grip so that the pole is rotating through his top fingers and in fact assist, steers it rotation). Becuase lavellenie does everything to not effect the elemental rotation of the pole (And it rotates much more than Bubkas) he is easily able to cover it at the top. heck he actually waits for it. Simply put, Lavellenie does a much better job of not fighting the elemental rotation of the pole.
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby charlie » Sat Jan 31, 2015 8:38 pm

I would like to get a discussion on the clearence of Lavillenie's 6 meter vault compaired to Bubka's 6 meter vault at his last world championship!!!

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

Unread postby Wan » Sun Feb 01, 2015 10:36 am

charlie wrote:I would like to get a discussion on the clearence of Lavillenie's 6 meter vault compaired to Bubka's 6 meter vault at his last world championship!!!

We should have this discussion after last RL's 6 meters competiton, I mean ... Let's see in 10 years... may be !

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

Unread postby grandevaulter » Mon Feb 02, 2015 2:45 pm

Will,

In your opening thread you claim that you will "illustrate" a physics approach. Where are your illustrations? Polevaultstudent has done all of the illustrating. Tim brought up "Conservation of Angular Momentum" . Like many of us, you are being dragged along on the the coat tails of individuals that have a greater understanding of physics and how they are applied to this event. You continue to regurgitate information that is supplied by others.

You continue to drag Altius into this and attempt to discredit him and his book. You will never be taken seriously as long as you issue false claims that Altius didn't understand physics. His credentials indicate that he was a mathematics specialist. Where he chose to approach this from the practical side, indeed he did understand what benefited his athletes.

Please keep us informed when you have a paper accepted to a credible publication or publish a book. I may buy a copy.

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

Unread postby PVstudent » Tue Feb 03, 2015 9:08 am

I have been very much engaged with significant changes taking place in my life and unable to continue my detailed mechanics (physics based comparative analysis) of the techniques employed by both Bubka and Lavillenie as I would have liked. However, some stability has returned and I will soon be able to continue that process.

Willreifer’s analysis I find confusing and am at a loss to explain why he thinks what he proposes is new or novel. Indeed I really do have personal difficulty in understanding much of what he has published in this forum. Due to his lack of definition of terms, idiosyncratic use of already established concepts such as gravity vector and positing of angles without any conventional framework employed to tell the reader what he actually means make his posts very difficult to follow let alone understand.
.
I have no doubt Will’s intentions are to be helpful and to unravel the physics principles employed by Bubka and Lavillenie. So far, he has not, as far as I can follow him, identified any physics principles that differentiate the technique differences that clearly exist between Bubka and Lavillenie during the first and second phases of pole support.

I also believe that he wrongly assumed that Altius did not understand the application of the principles of conservation of linear and or angular momentum employed by beginner to elite pole vaulters.

Since Altius is no longer with us to defend himself Will should retract his misinformed opinions in this regard. (This is the mild version of what I actually think!)

To move the discussion on, meet Charlie’s request and at the same time attempt, once again, getting everyone on the same page check out this video!

http://youtu.be/KrQWsMaABqM

Until I have some more time to continue to put up my interpretation of the available qualitative evidence I remain unconvinced by Will’s “physics” explaining Renaud Lavillenies technique in the first phase of pole support!

The video WAN referred us to, Renauds latest (2015) 6.00m clearance, shows in my opinion, Renaud drops his lead leg much less than in the past and that he displays much greater continuity of force / torque application from take-off to pole release. The speed of force / torque application appears to have also increased. Renaud has, I believe, become more powerful throughout both the compression and pole recoil phases!

If my observations are correct Will’s theoretical explanation for Renaud’s technique in the pole compression phase of pole support will require an explanatory physics conceptual analysis overhaul!
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willrieffer
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby willrieffer » Tue Feb 03, 2015 11:38 am

When Altius asks if Conservation of Energy is fact or opinion, I don't know that I could better illustrate what is going on. I don't have to construct this. It's in the record of this thread. It's not slander. I'm not making it up.

The timing and rate of the swing angle and its necessary relation to the CoM and gravity vector and thus that vectors effect on the compression and chord shortening of the pole are crucial to the vault. The more that the vaulter can delay the movement of the CoM forward, the more they can have the gravity vector resolve into the pole and not into swing momentum, the better the vault, that is, if they can do this and cover the pole. That is the trick. The gravity force I'm talking about adds to the compression rate of the pole, based on the progression of the swing angle to the shortening the chord, and thus by shortening it adds to its rotational velocity. There has been not one single reply that has addressed this directly in refutation. Not one. Everything around it? Yes. All over the map from personal attacks to a boondoggle of peripheral information. Oh, yes! Any sort of direct scientific refutation? None. PVStudent probably has the capacity, but has always, for whatever reason, just missed the mark. He blames me. And there is an onus on me to make this clear. All I can say is that I have tried from the beginning. But much of what is being "blamed" on me I have covered previously and elsewhere repeatedly. Repeatedly. And again. Repeatedly. And for you gentlemen, you offer few if any questions made charitably, but many accusations thrown wildly. Need I say more? Well, one thing more...

I must say, this is the most politically motivated and least rational forum I've ever seen on the internet...

There are a few people who actually seemed somewhat interested in this idea. Kirk, Tim, a few others. But my ideas are, well, they are going to be hard to understand for those not trained in physics. They are going to be hard to understand for coaches with even a bit of understanding of physics. Tim, I think called it, "staying behind the pole". And that would be it. Staying behind the pole in extreme because the physics says that is good. But for what good is this where one considers the deep and palpable political element here? Against the deep protectionism seen for those adhering to the PB Model. Or the misconstruction that comes from the emotional based defense of an old friend, which is actually admirable in its way. But as I've said, what I'm doing is two fold. The GRV assessment is not actually anti PB Model, but an extension. But to get at it you have to critique that model from a physics based perspective. It is about something they didn't worry about, the pole, and the vaulter's inside the swing relation and COM movement in relation to its chord shortening and energy storage.

Some of you, well, some of you, I just can't worry about what you think anymore. I've presented my thoughts here. They are here. Maybe someone will find them and make use of them. I used to perhaps think these forums were monitored by a wider spectrum of the greater PV community. I no longer think that is the case. It's just a little enclave of die hards dominated by a bunch of ax grinders...

I no longer really loiter over the site, and certainly not these forums. I come around once in a while when I have time to burn to check on some things. To see if someone worth while in the dialog has spoken up or showed up. The site still has meaning in other areas. But theoretical tech exploration? It appears I've probably wasted some time...

Will

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

Unread postby grandevaulter » Wed Feb 04, 2015 12:16 am

Vault3rb0y wrote: "If you're going to dig into the deep and complicated elements of physics, biomechanics, and physiology to explain a model of the vault, you have a responsibility to do so clearly, simply, and in a way that is easily understood by the average PV'er or enthusiast reading it from their couch"

Will, you must also truly have the knowledge to do so. One cannot comb over others posts and reuse their findings and claim those to be their own. NASA cut and pastes don't work either.

willrieffer wrote:When Altius asks if Conservation of Energy is fact or opinion, I don't know that I could better illustrate what is going on. I don't have to construct this. It's in the record of this thread. It's not slander.

That is not the question Altius asked Tim, go back and read it word for word. You can not explain, describe or illustrate it. Because that was not what he asked Tim.

willrieffer wrote:I'm not making it up.

You are making it up and took the question that Altius posed to Tim totally out of context. He questioned Tim if the laws of conservation of angular momentum still applied after the the rotation was shortened by the tuck. Altius knew the answer but out of respect for Tim, let him explain it. But you probably didn't read anything useful from Tim's response and only used Tim's vocabulary to make yourself appear be more qualified than you are.

But Charlie, Wan and Polevaultstudent have invited you to continue to contribute to the discussion. But please cease in your efforts to feed us rubbish.

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

Unread postby PVstudent » Wed Feb 04, 2015 11:50 am

Renaud Lavillenie as of February 2015 videos showing his current vaulting technique.

1 Renaud Lavillenie 6.00m 2015.
https://www.youtube.com/watch?v=NC1_vdhvmwc

2 Renaud Lavillenie Michelin Capital Perche 2015 (slow motion)
https://www.youtube.com/watch?v=Wp1bcKiPkIE

The image sequence that follows show Bubka and Lavillenie compared using frames selected from 6.00m vaults of their respective technique in the first phase of pole support from take-off to maximum moment of inertia of the vaulter with respect to the top hand axis of rotation.

I will make no commentary at this time so that viewers can digest the information.

Bubka v Lavillenie 1st phase of pole support Take-off to Max Moment of Inertia 1.jpg
Bubka v Lavillenie 1st phase of pole support Take-off to Max Moment of Inertia 1.jpg (95.75 KiB) Viewed 4862 times


Bubka v Lavillenie 1st phase of pole support Take-off to Max Moment of Inertia 2.jpg
Bubka v Lavillenie 1st phase of pole support Take-off to Max Moment of Inertia 2.jpg (96.75 KiB) Viewed 4862 times


Bubka v Lavillenie 1st phase of pole support Take-off to Max Moment of Inertia 3.jpg
Bubka v Lavillenie 1st phase of pole support Take-off to Max Moment of Inertia 3.jpg (94.56 KiB) Viewed 4862 times


The following video shows the actual motion recordings from which they have been extracted.

http://youtu.be/KrQWsMaABqM

Viewers comments on the respective actions of the lower arm and the lead leg contribution to pole bend and propulsion in this phase of the pole support of each of these vaulters would be very helpful in moving the discussion forward.

I would like all readers to know that my contributions to this forum are not the result of "boondoggle". I have received no payment or support for any of the submissions I have made to PVP. I give of my time and effort freely in making my contributions. I do not consider my effort to be a waste of time but is, hopefully, my contribution to advancing my own understanding and I hope that of readers of our sport of pole vault.

"boondoggle" rather harsh criticism! I believe my contributions have most certainly not been a waste of my time and that of all readers of this forum.

Willriefer are you a physicist? A simple yes / no response is all that is needed.

I am not a physicist but have been educated as a scientist specialising in the field of biomechanics and have also coached Elite International Level Pole vaulters.

I openly declare that I make no claims to expertise in the discipline of physics.

Readers judge for themselves my competence in the application of principles of mechanics (kinematics and kinetics) to advancing our understanding of pole vault technique.

As always I am grateful to have my errors exposed and corrected so that I continue to learn and advance my personal understanding of this very demanding athletic discipline.
Every new opinion at its starting, is precisely a minority of one!

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

Unread postby KirkB » Wed Feb 04, 2015 2:51 pm

willrieffer wrote: ... All over the map from personal attacks to a boondoggle of peripheral information.

PVStudent wrote: "boondoggle" rather harsh criticism! I believe my contributions have most certainly not been a waste of my time and that of all readers of this forum.

From wikipedia:
A boondoggle is a project that is considered a useless waste of both time and money, yet is often continued due to extraneous policy or political motivations.

I personally don't think PVStudent's contributions to this topic have been a waste of time, and I don't think they're motivated by anything other than altruism.

I can also say the same about Willrieffer's contributions.

Perhaps the 14 frames each from SB and RL (above) can be used as a common reference to get this thread back on track. And why stop there? Maybe we can continue the comparison right on through to the frame where they each clear the bar at 6.00m?

It is clear that RL has a longer/stiffer bottom arm and a lower lead leg than SB. But what struck me at first glance is that their first 5 frames are so similar to each other! But maybe that's just because PVS did such a good job at matching them up.

The downside to matching them up this way is that if there's a different number of actual frames (at 24 fps) between each frame number shown, then the vaulter with more intermediate frames is moving his body parts faster than you might surmise. This may even be different vaulters at different stages of their complete vault.

Let's look at Frame 5:

I'm surprised at how RL's lead leg isn't much lower than SB's. It's clearly lower, but not by as much as I would have guessed. (The differences in lead leg position become more pronounced in Frames 6-14.) This tells me that RL is getting fairly good takeoff drive with his lead leg - more than the typical tuck/shooter or drive vaulter.

SB's chest is further forwards; and his bottom arm is bent more at the elbow. Consequently, his top arm is stretched further BEHIND his ear than RL's, and his body posture is more upright. I have always believed (and continue to believe) that this tremendous stretch in the C position (and body posture) is what separates SB from most other vaulters (regardless of other aspects of their techniques).

By frames 10-14, it becomes clear that RL is getting more bend out of his pole (you can see RL's pole bending much more past horizontal than SB's). It should also be clear to everyone that RL's swing is hinged about halfway between his upper and lower hands, whereas SB's is hinged almost at his top hand. This is due to the bottom arm pressure that RL is applying, compared to SB. In fact, I suggest that SB isn't applying much pressure to his bottom arm at all (if any). Most of SB's weight is being held through his top arm.

This allows SB's momentum to continue to move towards the pit, and at the same time, it allows his momentum to swing from his hinge-point (near his top hand). Meanwhile, the pole is rolling to vertical faster than RL's (we'd have to verify this by looking at all frames up to releasing the pole).

RL's momentum is slower. He's storing more potential energy into the pole, and the pole is bending more extremely. And YES, he's staying lower for longer. If I didn't know better (if I hadn't seen the subsequent frames, and was watching him vault in real time for the first time), I'd think RL is going into a stall. Said a little differently, if this was SB (and knowing his usual body positions AND MOMENTUM at Frame 5), I'd fear that the pole isn't rolling towards vertical quickly enough for him to make the pit.

I can't help but think that RL's pole technology allows him to do this (better than SB's pole technology), independent of their TECHNIQUE or ATHLETICISM. But I have no scientific basis for asserting this. I do know that pole technology has continued to improve in the past couple decades, but enough to allow RL to clear 6.00m with "inferior" technique to SB's? Or is SB's technique scientifically inferior? This is what I can't say, and this is what I think we all want to know (isn't it?)!

Static frames are fine, but what you CAN'T see is the dynamics of each vaulter. I'm hoping that PVStudent can scientifically analyze the deltas between frames to show the timing of each of their body parts - from frame to frame. Meanwhile, the deltas can be eyeballed to estimate how quickly each body part is moving (and which vaulter's body parts are moving relatively faster).

I'm not going to do any more analysis than this. Clearly, PVStudent, Willrieffer, and others can explain this much better (and much more scientifically) than me. I'm just trying to get this thread back on track.

Less bickering and more scientific analysis! :idea:

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

Unread postby KirkB » Wed Feb 04, 2015 3:10 pm

willrieffer wrote: The timing and rate of the swing angle and its necessary relation to the CoM and gravity vector and thus that vector's effect on the compression and chord shortening of the pole are crucial to the vault.

The more that the vaulter can delay the movement of the CoM forward, the more they can have the gravity vector resolve into the pole and not into swing momentum, the better the vault, that is, if they can do this and cover the pole. That is the trick.

The gravity force I'm talking about adds to the compression rate of the pole, based on the progression of the swing angle to the shortening the chord, and thus by shortening it adds to its rotational velocity.

There has been not one single reply that has addressed this directly in refutation. Not one.

Willrieffer, I THINK you make some good points here, but I'm not sure.

What exactly do you mean by "gravity vector"? That EXACT term has zero hits on google.

Unless your terminology is well-understood, your points are lost.

When googling "gravity vector", Wikipedia points to "scalar-tensor-vector gravity": http://en.wikipedia.org/wiki/Scalar%E2%80%93tensor%E2%80%93vector_gravity

Googling "gravity vector", also finds this scientific paper: http://www.hep.princeton.edu/~mcdonald/examples/vectorgravity.pdf

Which of these are you referring to? Or do you have a third definition, perhaps more specific to PV?

Thanks for any clarifications you can make about what you mean. If we can understand what you mean, then we can reply specifically to your point.

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


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