GRV: Lavillenie - From Stall Swing to World Record

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

Unread postby KirkB » Tue Feb 24, 2015 8:23 pm

PVDaddy wrote: Owe and he's a Tucker Kirk, so how can you say there should never be one!?

My tagline was changed a couple years back. It's now:
Run. Plant. Jump. Stretch. Whip. Extend. Fly. Clear. There is no tuck! THERE IS NO DELAY!

It used to say "THERE IS NO ROCKBACK".

The most important part of my "new" tagline is that "THERE IS NO DELAY".

I'm not against the tuck per se; it just that for most mortal vaulters, the tuck and the delay go hand-in-hand. I would not teach a tuck to any young aspiring vaulter, as it would inevitably come with a delay, which is a big no-no (according to the Theory of Continuous Motion).

I've already commented on several occasions over the past year (since RL set the WR) that he DOES have a tuck, but very little delay (if any). Way less delay than other tuck-shooters!

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 rainbowgirl28 » Wed Feb 25, 2015 12:25 am

PVDaddy just got a week long vacation.

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

Unread postby KirkB » Wed Feb 25, 2015 4:04 am

^bump
PVStudent wrote: Obviously there is substantial advanced Coach and Vaulter interest in the question broadly defined as “What is the role of the bottom arm in the pole support phases of the vault performed with flexible poles?”

PV Daddy has subjected readers to his explanatory theories to account for his observations made from his examination of a single exemplar 6.00m vault by Sergei Bubka performed in Paris on July 13th 1985 and recorded on slow motion cine film by Jacques Piasenta.

He claimed to have constructed his Agenda 21 largely upon this primary source and has tried to reinterpret the well known views of Vitaly Petrov (and others) to suit his idiosyncratic cognitive understanding of modern flexible pole vault technique. The perspectives and concepts he persists in putting up on PVP are sometimes demonstrated to have been brazenly plagiarised.

I believe PVDaddy is unjustifiably overconfident and ridiculously assertive in his claims as to the originality of his personal theoretical understanding of pole vault technique. When challenged he usually demonstrates lack of understanding.

PV Daddy uses jargon elicited by trawling through the internet publications of the work of others whose ideas he then subverts and twists to give his arcane theories some semblance of credible authority.

For example most of these terms and concepts; Gymnastic “Tap” swing, Whip Downswing, Bottom Arm Push Out, Active I, angular momentum are regurgitated, in a contextually correct manner only to leave knowledgeable readers puzzled by contradictory or erroneous interpretive commentary by PV Daddy.

PV Daddy continues to regard the views he expresses on PVP as unassailably correct, despite knowledgeable, wise, patient and initially tolerant and kindly advice from respondents that show his bravura confidence in his own conceptualizing to be unwise and unwarranted. This has been particularly the case in his PVP exchanges on the role of the bottom arm in flexible pole vaulting.

Unfortunately PV Daddy’s misperceptions and occult explanations of them have not only muddied the waters to the point where confusion reigns but exasperated a number of stalwart PVP contributors who have given up trying to reason with him.

PV Daddy also misinterprets warning shots, indicating he is in danger of being “hoisted on his own petard”, as intentional and unwarranted destructive flak when his ideas are picked out, exposed and highlighted by the searchlights of reason and experience directed at his ideas by the less gullible PVP readership.

For example he recently and most bizarrely poured vitriolic scorn on Altius and Agapit for suggesting the concept of a continuous pulling action throughout the pole support phase of the vault. Then upon very concise, precise and mechanically and biomechanically well founded advice from “I am the Walrus”, “Coach Eric” and “CoachJVinson” he is now an advocate of pulling throughout this phase of the vault.

For those of us who have only a rudimentary grasp of the complexities of flexible pole vaulting this latest chameleon like change to the colour of PV Daddy’s opinions is mesmerizing.

PV Daddy is able to change his opinion at will to whatever viewpoint he perceives will blend perfectly to the argument that exposes error on his part. PV Daddy cites the latest video clip he recommends to us to back up his new look opinion.

Big, Big Mistake PV Daddy!

The video compilation and the conceptual commentary that you now recommend as supporting your concepts and perspective on the action of the lower arm is, of all things, Surprise, Surprise, taken from the DVD that accompanies BTB2 and authored by Altius.

Why is it not possible for PV Daddy to get the message?

Why is it that PV Daddy cannot “see” what many of the experienced readers of PVP power see when they view this same slow motion film sequence of Bubka’s first official pole vault jump to clear the 6.00m barrier some twenty eight years ago?

Why apparently is it not possible for PV Daddy to entertain the possibility that his lack of knowledge and experience might conceivable make some of his observations blind to actions Sergei Bubka actually performed?

Why is it not possible for this pole vault technique neophyte to concede that his foundational observations could possibly be wrong?

Could the answers to these questions be attributed to:
(1) Attention blindness (You can’t see something if you have no knowledge of it!)
(2) Over Confidence in our personal ability to be aware and accurate in witnessing events that are unexpected, unanticipated or novel to us.
(3) Pre cognitive priming. (Perception and belief is profoundly affected by pre-knowledge, preconception and intentional directional focussing of sensory attention.-We see what we expect to see and want to see! We hear what we expect and want to hear! Both these sensory systems are profoundly influenced by experience, belief and imagination. Memory recall and remembering of sights and sounds is also notoriously unreliable.)

I explore these questions in an attempt to redirect the reader’s attention back to the pole vault motion realities contained in the original video used as the primary source of PV Daddy’s observations.

The specific visual references I provide will be uncoloured by my personal prejudices and biases so far as this is possible.

More importantly they are free of PV Daddy’s clouds of confusion, smoke screens and clever cloaking of his of lack of knowledge of the technical demands of pole vault technique with copious quantities of technical jargon.

My hope is that readers will regain an undistorted visual reference of what Bubka actually did in his historic 6.00m jump.

First consider the following well known perceptual illusion.

Muller Lyer Illusion.jpg
Muller Lyer Illusion.jpg (22.43 KiB) Viewed 583 times


The observer’s brain can readily accept that the lines A1 and A2 are of the same length. The way in which most human brains perceive the lines B1 and B2 is that they are not the same length as each other with line B2 clearly longer than Line B1. The illusion persists despite our cognitive recognition that all 4 lines are the same length.

Why it is extremely difficult to persuade our own brain perception mechanisms and processes to accept the intellectual (cognitive) understanding that the lines possess the same length is not fully understood.

http://youtu.be/pcC2HeHHFYw

Secondly let us examine PVP reader’s capacity to accurately observe video of an unfamiliar action sequence when required to deliberately pay attention to selected features occurring in it.

Please watch this video before you read any further and follow the instructions with your maximum focussed attention.
View the video clip one time only, without stop framing it or slowing it down, and return immediately to this page.

http://youtu.be/BnTqI2ullfY

Now that you have undertaken the observational accuracy test, answer the two questions posed at the end of this post. About 50 % of you will answer yes to question 1.
Extremely few if any will be able to answer yes to question 2.

You may need to view the video again to verify that you have not been deceived!

http://youtu.be/BnTqI2ullfY

Thirdly observe what happens in this video clip of pre-cognitive priming at work.

http://www.youtube.com/watch?v=6JUxaMmtvTs

Readers interested in exploring this further might enjoy the u-tube video of Michael Shermer discussing “The pattern behind self deception”.
Pattern recognition and identification informs and assists construction of an individual’s world view and intuitive system of beliefs. Determination of the validity of beliefs is prone to making false positive (type 1 error) or false negatives (type 2 error) depending on the relative cost of the consequences of each error type.

The Primary source of evidence used by PV Daddy:

http://www.youtube.com/watch?v=_-UwBaf8f98

The video has three constraining influences on viewer perceptions. These must be kept in mind in interpreting the images recording the technique used by Sergei Bubka on this occasion:
1. The camera is panning in the direction from left to right
2. The camera is slowly tilting upwards whilst panning and neither camera motion is perfectly smooth
3. The vaulter moves slightly out of the fore-aft (saggital) plane, initially toward and then away from the source of the camera location. This has subtle distortion effects on the vaulter image size and proportions as recorded in the frame by frame images of the film.

These limitations in the source material must be recognised as lowering the `certainty’ with which the images can be relied on as being “true” representations of the actual motion of the vaulter being recorded by photographic means on this occasion.

The still images and my drawing are of the 1st phase of pole support after take-off as recorded in the slow motion footage taken by Jacques Piasenta of Bubka’s official 6.00m jump made on the 13thJuly in 1985.

I only offer descriptive observations to PVP readers who I leave to draw their own conclusions in regard what PV Daddy exhorts and commands us to believe is happening in this stage of modern flexible pole vault technique of Sergei Bubka.

The drawings were made from traced outlines of the vaulter images in each of the still frames shown. In making the outline drawings I have ensured that the images and drawings coincided as closely as possible to the still frame image of Bubka with respect to stationary object landmarks in the field of view from frame to frame.

There were 197 video frames from take-off to pole final release. This represents 100% of the pole support time of the vault. The time between each image is 5% of the total pole support time. The 8 drawn images deal specifically with the 1st phase of pole support which is 40% of the total pole support time in this specific instance.

The position of Bubka’s total body centre of mass (C of M) was calculated using digitized x,y co-ordinates at body segment proximal and distal end points located on each individual image using the body segment C of M location data and segment end point definitions of De Leva to locate the centre of gravity of the vaulter. (Since ideally the segmental C of M should be determined on an individual by individual basis this is impractical when live humans are being observed. The segmentation method may not give the exact C of M specific to the individual concerned. However, the error involved is very small and relatively constant between images taken of the same individual).

Some subjectivity in clearly identifying digitising landmarks on the vaulter images is involved in the manual digitising method used. I have over 35 years experience in performing C of M determination using this method and am highly skilled with very high reliability in measurement reproducibility. (Readers will have to accept my word for this claim.)

All displacement pathways shown in the images were drawn with the curve drawing tool from Powerpoint by joining the body segment end points using “ click-move-click “technique.

Bubka Analysis 1.jpg
Bubka Analysis 1.jpg (93.55 KiB) Viewed 583 times


Bubka Sequential displacement pathways Hands, C of M and Feet.jpg
Bubka Sequential displacement pathways Hands, C of M and Feet.jpg (96.07 KiB) Viewed 583 times


Careful examination of the diagrams shows any downswing of the trail leg is of small amplitude depth (approximately half of one of Bubka’s natural foot lengths I estimate to be about 15 – 17 cms). The lead leg downswing is also relatively small slight.
Both trail and lead toe tips rise upward immediately after take-off before they can be seen to exhibit any possible observable downward component.

The small amplitude downward component of the trail leg lasts for 5% of the total pole support time and is at a maximum at about 15% from the start of the total pole support time.

Trail leg swing is initiated approximately 10% of the time in from the take-off

The top grip hand, the lower grip hand and the vaulter’s total body Centre of Mass all simultaneously rise vertically and displace horizontally from the instant of take-off until the vaulter passes through the body location and body orientation configuration shown in image 6 where the rate of pole penetration clearly is shown to slow down rapidly.

For the first 25% of the total pole support time (Image 1 to 5) the horizontal component of the total system displacement is predominant since the tangential velocity component of the trail leg lower leg and foot mass has their highest radial acceleration from image 3 to image 5.

This simple kinematic description shows that the “whip-swing” used by Bubka in this example vault is the predominant driving mechanism assisting the vaulter’s horizontal take off momentum to flex and at the same time ensure pole penetration forwards. This is clearly shown by the displacement pathway achieved by the lower leg and foot of the of the trail leg generating a large predominant horizontally directed tangential force.

The diagrams also highlights that for the first 10 % of the total support time (Images 1 – 3) there is little or no forward swing involving the lower limbs about the local axis of rotation at the top hand.

Instead the vaulter allows his take-off inertia to project his whole body upwards and forwards so that it advances forward at a faster rate than the hands whose motion is retarded relative to the rate of motion of the vaulter’s C of Mass. The images in the diagram clearly show the actual displacement of the top grip hand is significantly shorter in length than the length of the displacement pathway of the vaulter’s total body centre of mass.

Simply put Bubka does not demonstrate significant “Downswing” but demonstrates that the force and timing of the initiation of a “Whip-Like” leg swing is such that it effectively drives the vaulter pole system in a predominantly horizontal forward direction. The displacement pathways of his C of M, and Bubka’s hands gripping the pole show continuous elevation for the first 30% of the time of pole support which raises some question as to the validity of “Downswing” as a valid or useful instructional construct to apply in teaching or coaching flexible pole vaulting.

There are many more simple observations based on the particular vault images I have produced to show where PV Daddy’s attention blindness, overconfidence in his perceptual awareness, and pre- cognitive priming and biases may be contributing factors to why he misses so much of the relevant and important information in Bubka’s technique.

I leave my observations at this point and encourage readers to make up their own minds.

Finally I hope that there are few, if any, readers who look at these images and conclude that Bubka could possibly be pushing the pole at any point in the pole support phase depicted.

The so called “pushing out of the bottom arm” in images 7 -8 is an illusion. Careful scrutiny of pole bend and hand grip displacement paths whilst thinking about the vaulter’s weight force magnitude at this time should dispel that myth. Note that centripetal force is required to cause angular motion and that newtons 3rd law requires equal and opposite forces at all times! (Centripetal force is directed inward towards the axis of rotation and the pole must therefore pull on the vaulter and the vaulter pull on the pole in the opposite direction. Pulling by flexing the arms and shoulders must obey Newtons Law.)

Like most neophytes PV Daddy, due to his lack of awareness finds it difficult to accept that his observation could possibly be faulty or he lack sufficient discrimination to see the essential pattern of the overall structure due to his concentrated focus on individual bricks.

This is the charitable view.

PV Daddy can carry on his fantastic ramblings because I would not deny him his right to free speech, free thought and any other right but I am going to exercise my right to ignore him on PVP topics in the advanced section.

It is disconcerting and irritates me that the quality of discussion on PVP is continually degraded by this person who is impervious to the pleas of sincere and genuine pole vault enthusiasts to exercise more effort and caution before dismissively denigrating points of view of other discussants.

Question 1. Did you see the Penguin?
Question 2. Did you see the plastic model of a human brain?


Posted Wed Sep 25, 2013 by PVStudent on the "pushing back out during the swing" thread here: http://www.polevaultpower.com/forum/viewtopic.php?f=38&t=30135&start=216

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

Unread postby PVstudent » Tue Mar 03, 2015 4:50 am

The accounts of what Renaud Lavillenie does during the pole compression (phase 1 of pole support… to indicate that the pole is in contact with the ground via the planting box and that the vaulter is being supported without ground level contact other than by means of the pole) have been wildly exaggerated.

Under the guise of claimed expertise in science and physics in particular some discussants have been guilty of leading the readers on a wild goose chase.

Pages 8 – 15 of this forum have been diverted from the topic by some discussants using so called scientific explanations to support a particular theory without following the tried, true and tested methods of scientific thinking and analysis.

As these later pages unfolded it is clear to me and other readers that Willriefer, whilst he has clearly some understanding of physics and the fundamental concept of conservation of energy and momentum is unable to clearly articulate his idiosyncratic use of “Gravity Vector” relationships in Renaud Lavillenie’s vaulting technique.

"Gravity Vector" when carefully disentangled shows that what he mean here is the direction of the vaulter’s weight force always acts vertically and that the gravitational field due to the earths mass produces an acceleration of approximately -9.8m/s/s in the direction radially towards the centre of the earth. Why wrap this up is a mystery unless Will was trying to be smart or showing off his assumed familarity with the intricacies of gravitational field theory.

When all this is sieved through, Will's wisdom on the issue had already been addressed by myself and others using accepted and relevant nomenclature and concepts. Also I still remain sceptical that Will fully grasps the significance of the vaulter mass gravitational field and its implication in the application of Newton’s 2nd and 3rd Law

His use of internet resources to assist his explanatory power has been remarked upon by others expressing a view with which I concur which I paraphrase as “Willriefer is recasting old wine in new bottles and the wine, despite being touted as of the finest quality, is past it's used by date!"

(I use the phrasing above in honour of my good friend Altius who was a true connoisseur of good wine and a passionate devotee to pole vault coaching and pole vault coach education.)

Willriefer wants to be taken seriously and that the explanations, he expresses in these forums, are the epitome of science applied to pole vault technique.

His attempts to do so are indeed commendable but nevertheless continues to miss the communication bull’s eye being led astray by PVdaddy and his attempts to converse sensibly with that individual. The result has been total confusion and the core issue lost in the esoteric, arcane dialogue between them.

Charlie, Decamouse, Grandevaulter, Kirk and others have also tried to get this discussion back on track to little avail.

My position on this forum question has been to attempt to set up a framework to facilitate useful dialogue.

I am going to attempt, yet again, to bring the discussion back on track and to explore whether Will is actually being as scientific as he claims.

On this topic I make the claim, on the basis of the observational evidence to follow that Willriefers explanatory thesis in regard to Renaud Lavillenie’s technique in the first phase of pole vault is an “hypothesis based on imagination rather than science!”

The first principle of physical science is to make an observation of a physical phenomenon and to describe the phenomenon accurately and precisely so that others are able to clearly identify the phenomenon.

The second principle is that the observations are replicated independentlhy of the original observer and tested as to their reliability and reproducibility and to determine means to measure and record parameters that accurately describe the phenomenon in question.

The third principle is to advance and test hypotheses to determine possible causative agents giving rise to the phenomenon being described.
I think Will has arrived at principle 3 before confirming that the phenomenon actually is occurring in the case of Renaud Lavillenie.

(Many thanks to CANAG for reference to original video on which my observations rely.)

I direct readers to these observations of a recent 6.01m jump by Renaud Lavillenie on Feb 22nd 2015.

http://youtu.be/sMpzTO8h5qk

The graphs that follow show the pathway profile for the COM of this jump.

The readers are politely asked to accept that the methods used to determine the location of the vaulter’s total body centre of mass (COM) by means of digitizing body segmental landmarks in the selected video images are reliable and accurate. The methodology used is well know and accepted. (Standard biomechanical video analysis procedures were used to obtain the raw data on which the graphs were constructed by a person with 40 years of professional practice in biomechanical analysis, research. Coincidentally this same individual has coached National, Olympic and World Championship Medal Winners in Pole Vault. ).

Since the camera, so far as I can tell, was stationary throughout the filming process, did not pan or elevate/depress nor change focal length or camera height with respect to the vault runway the images allowed for simple pixel by pixel analysis in the x and y coordinate directions. No attempt was made to scale the measurements to real life values because exact scaling values were not available. Similarly the time unit employed was the single frame of video. Each analyzed frame took about 20 minutes to manually process and record.

I personal wrote the software to use the x,y coordinate data to compute x,y coordinates of the location of the COM using the standardised protocol of DeLeva. These values in pixel units were then located on the video image. The COM data was summarized in graphical form and reported below and in the next post.

I make no interpretation at this stage and readers can judge for themselves what they observe and what the data records.

Readers I hope will draw their own conclusions as to the veracity of scientific claims being made by Willriefer in regard to the causation of Renaud Lavillenie’s wonderful performances.

The observations of this vault are limited from a scientific perspective but do raise some doubt concerning the accuracy, assumptions and claimed observation upon which Will rests his theory.

It remains for others to determine if my observations are replicated in the evolving pole vault technique used by Renaud Lavillenie World Indoor Record Holder in 2015.

Coaches I hope will find the video and graphs helpful in clarifying their observation of the use of the lower arm in Renaud's current pole vault technique.

Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 2015.jpg
Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 2015.jpg (94.04 KiB) Viewed 7120 times


Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 22nd 2015 frames 1315, 1320, 1325 and 1330.jpg
Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 22nd 2015 frames 1315, 1320, 1325 and 1330.jpg (78.97 KiB) Viewed 7120 times


Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 22nd 2015 frames 1335, 1340, 1345 and 1350.jpg
Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 22nd 2015 frames 1335, 1340, 1345 and 1350.jpg (79.01 KiB) Viewed 7120 times
Last edited by PVstudent on Tue Mar 03, 2015 8:21 am, edited 3 times in total.
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby PVstudent » Tue Mar 03, 2015 4:58 am

Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 22nd 2015 frames 1355, 1360, 1365 and 1370.jpg
Displacement Path Renaud Lavillenie's COM 6.01m Jump Aubiere February 22nd 2015 frames 1355, 1360, 1365 and 1370.jpg (82.99 KiB) Viewed 7121 times


The diagram below gives an indication of the uncertainty of measures in digitizing and determination of the COM for a different vault by Renaud Lavillenie.

The diagram indicates the uncertainty with measurement and calculation of the angular displacement and velocity of the vaulter's COM in the video images shown.

Digitizing Renaud Lavillenie Frame 428 COM Location Compared to Frame 429 Immediately following toe-off 3.jpg
Digitizing Renaud Lavillenie Frame 428 COM Location Compared to Frame 429 Immediately following toe-off 3.jpg (90.9 KiB) Viewed 7121 times


Readers are also informed that there are limitations in the use of segmental methods in determining the location of the vaulter's COM. They are beyond the scope of this discussion and I will not bore the reader with details of which I am aware.

However, despite these limitations the results will assist the coach to observe more accurately and to visualize the COM pathway during pole compression and recoil in Renaud Lavillenie's 6.01m vault.
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby canag » Tue Mar 03, 2015 12:18 pm

Thanks PVstudent for this very interesting insight. I am familiar with this kind of kinematic analysis as I had developed such a program in a science project to analyse efficiency in the last phase of long jump (difference between CoM fall position and achieved mark). I totally agree on your remarks about gravity "vector" fields, it is actually not a complicated phenomenon, gravity pulls every solid (hence every body parts) to the ground with a constant vertical force.

Actually, the force isn't exactly "constant", as gravity "constant" g slightly changes around the globe. Calculation shows the surprising result that variations of gravity between London and Rio makes a difference that results in more than 1 cm difference for the jump! Regarding that aspect, Mexico would actually be one of the most favourable place on earth to pole vault :) (+2.4 cm)
Sources:
http://xkcd.com/852/
http://en.wikipedia.org/wiki/Gravity_of_Earth

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

Unread postby KirkB » Tue Mar 03, 2015 2:20 pm

Good stuff, PVStudent (as always)! :yes:

I don't want to divert from your main points, but I'm just curious if you can readily determine from your analysis of Canag's vid what RL's takeoff trajectory is?

Linthorne has published a paper ...
J9. Linthorne N.P. "Mathematical model of the takeoff phase in the pole vault" Journal of Applied Biomechanics 10 (4) 323–334 (1994). (Abstract) (Publisher)

... that puts the AVERAGE trajectory of a vaulter at about 18 degrees, but this was long before RL became the WR holder.

So I'm just curious whether he's above or below this 18 degrees. And do you happen to know the angle of SB's takeoff trajectory?

I have a hunch that RL might have a lower trajectory than SB, but I don't know if it holds water (scientific scrutiny) or not.

Thanks.

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

Unread postby KirkB » Tue Mar 03, 2015 2:26 pm

canag wrote:
http://xkcd.com/852/

Funniest PV comic ever !!! :D :yes:

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

Unread postby PVstudent » Tue Mar 03, 2015 11:38 pm

Canag I enjoyed the cartoon.
Your clarification re gravity vector is why I stated “ … approximately -9.8 m/s/s”.

Bob Beamon’s phenomenal long jump WR in Mexico (1968 Olympics) might just have been increased by about the amount you suggest!

Kirk, I am very conversant with Linthornes paper you refer to.

Linthorne’s average 18 degrees is about right but a representative sample of elite athlete “take-off angle” data range is a better indication of the acceptable variation to be expected in modern pole vault.

My life is rather turbulent at the moment (selling our family home of 30 years) and it will take me some time to locate the data for a number of Bubka’s jumps which I have on an external hard drive locked up in storage.

Until I can have a look at Bubka’s Paris 6.00m jump and analyze his take – off on that occasion I leave you with the take-off angle data for Dimitri Markov who a was a “tuck” inverter in the vault. He was not, I hasten to add, a “shooter” in the conventional meaning of the term applied to the pole vaulter recoil phase (Phase 2 of pole support).

Enjoy.

Markov C of M Determination.jpg
Markov C of M Determination.jpg (74.42 KiB) Viewed 7067 times


Markov Paris 2003 1.jpg
Markov Paris 2003 1.jpg (68.93 KiB) Viewed 7067 times


Markov Paris 2003 2.jpg
Markov Paris 2003 2.jpg (72.79 KiB) Viewed 7067 times
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Re: GRV: Lavillenie - From Stall Swing to World Record

Unread postby canag » Wed Mar 04, 2015 5:43 am

KirkB wrote:I don't want to divert from your main points, but I'm just curious if you can readily determine from your analysis of Canag's vid what RL's takeoff trajectory is?
Kirk


From PVStudent analysis of CoM position curve, it is possible to extract the take-off angle (=angle above horizontal line for first four points on the right), I get between 15° and 16°. The camera is a little above ground level, so this might shrink the angle a little, which might in reality be around 16° to 18°. So very close to one cited from the paper you mentioned.
(for the record, I am neither the owner nor the producer of the videos I post links to, this particular one was put on youtube by Renaud himself)

PVstudent
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Location: South Australia

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

Unread postby PVstudent » Wed Mar 04, 2015 7:22 am

Thank you CANAG for your clarification re video and the suggested angles.

I'm very happy that you acknowledged the video owner and the source.

I have downloaded every single frame of the jump sequence I have referred to and will attempt to take account of the distortion introduced by the rectangular scale differences in the dimensions of the individual pixels.

This will require finding some definite known horizontal and vertical real life actual object dimension located within the visual field of the camera so that the actual real life values of change in vertical rise of the COM in (m) divided by the change horizontal displacement in (m) and thereby obtain the actual ATAN of the angle of projection.

If the calculation is based on the video pixels then dy/dx as ATAN obtained will give an underestimate of the real life angle.

"The Question" remains does the evidence presented assist you in determining whether Renaud "PULLS" or "PUSHES" with his lower grip arm in the compression phase of the vault?

Bear in mind that he is suspended below the pole flexible "lever" which at the other end is in direct contact with the surface of the earth via the planting box.
Every new opinion at its starting, is precisely a minority of one!

charlie
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Joined: Thu Dec 22, 2005 11:36 am
Location: fitzgerald,georgia

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

Unread postby charlie » Wed Mar 04, 2015 8:26 am

He doesn't push, he PRESSES UP with the inside pad of his left hand!


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