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/pcC2HeHHFYwSecondly 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/BnTqI2ullfYNow 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/BnTqI2ullfYThirdly observe what happens in this video clip of pre-cognitive priming at work.
http://www.youtube.com/watch?v=6JUxaMmtvTsReaders 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=_-UwBaf8f98The 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?
(+2.4 cm)
