What is your correct takeoff point?

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Re: What is your correct takeoff point?

Unread postby PVstudent » Sun Aug 25, 2013 11:12 am

I invite readers to examine the slow motion video made from original footage taken at the rate of 25 pictures per second at an oblique angle view of the 1147 and the 1147B jumps.

http://youtu.be/h1WZ_AJF_EQ

It is still difficult to be fully certain that both these jump were in fact pre-jumps without the evidence presented from the forces being registered under the take-off foot and from the planting box via the pole tip.
The sceptics will, I suspect, remain unconvinced that pre-jumps have been used by some elite male and female pole vaulters during elite competitions.

Just so you can see the evidence for PSJ Jump1147B the Force Time Graph is shown below.

Pre Jump 18.jpg
Pre Jump 18.jpg (93.28 KiB) Viewed 8817 times


I show the detail of the pre – jump take-off and pole tip rear wall strike in jump 1147B in the graph below.

Pre jump 20.jpg
Pre jump 20.jpg (87.25 KiB) Viewed 8817 times



Most noteworthy is the fact that vaulter PSJ and the pole were airborne for about 9 milliseconds before the pole contacted the planting box.

Clearly the take-off was completely “Free” from external resistance (other than gravitational force and air resistance) affecting the motion of both the vaulter and pole. The pole contacted the planting box having been in linear translatory sliding motion with pole tip rolling for about 23 /24 milliseconds.

There can be no doubt based on the valid and objectively measured data recorded during training jumps over a 5.0m high bungy cord soft bar that at least ONE vaulter has existed on the planet who could use, on a regular basis, a “Pre - Jump” (subject to a caveat in relation to gravity and air resistance and the very low friction force in the pole slide relative to the inertia of the total vaulter + pole system).

I conclude that “Pre – Jump take-offs” were functionally achieved by vaulter (PSJ) + pole, as a total system.

By being completely airborne for a matter of milliseconds and continuing, minimally interrupted by pole sliding friction, for a further 1 to about 6 hundredths of a second when pole-tip rear wall impact occurred vaulter PSJ has clearly demonstrated a number of successful vaults using this method of pole vault take-off.

I make this conclusion based on more than just the pre – jumps that have been shown to PVP readers.
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Re: What is your correct takeoff point?

Unread postby PVstudent » Sun Aug 25, 2013 11:55 am

I am now in a position to answer Kirk Bryde’s question on the basis of the facts as far as I have been able to determine them.

The journey has been long, very arduous and extremely time consuming for me. I hope I have used the empirical evidence visited along the way to clarify a rationale based on scientifically sound principles in making the analysis of the pole vault take-off.

Here is Kirks question as he posed it to me:

“If a free takeoff is a mere millimetre (or thereabouts) off the ground and a pre-jump is something much more substantive than that (e.g. Fefanova's technique), why does Agapit say that anything more than a mere millimetre is inefficient? Or why does Bubka (via Altius) say that a pre-jump would be even better than a free takeoff? “

First some factual data in regard to the first ever officially recorded Pre –Jump by Delko Lesov of Bulgaria in the Junior World Championship in 1986.

Velocity at take-off = 8.6 m/sec
Horizontal Velocity = 8.1 m/sec
Vertical velocity = 2.7 m/sec
Angle of Projection COM = 19.5 degrees above horizontal.

The researchers said that Lesov was in the air for 1/hundredth of a second ie 10 milliseconds.

Vertical Displacement of the COM is 2.7 m/sec x 0.01sec = 27 millimetres (2.7 cms)
Horizontal Displacement of the COM is 8.1 m/sec x 0.01sec = 81 millimetres (8.1 cms)

Using the total pre-jump time of 0.032 second (time from take-off to pole tip impact for PSJ in Jump 1147B) and the same take-off kinematic parameters as determined for Lesov:

Vertical Displacement of the COM is 2.7 m/sec x 0.032sec = 86.40 millimetres (8.64 cms).
Horizontal Displacement of the COM is 8.1 m/sec x 0.032sec = 259.2 millimetres (25.92cms).

I think it is reasonable to suggest that the vertical displacement to be expected in a Pre-Jump is around 2 cms to 10 cms (ie 20 -100 millimetre range: remember 25.4 millimetres is 1 Inch).

The COM horizontal displacement can reasonably be expected to be between 8 cms and 30 cms (80 to 300 millimetres in a pre-jump.

In a pre-jump the vertical displacement of the vaulter’s COM is estimated to be in the range of less than 1 inch to approximately 4 inches (25.4 to just over 100 millimetres).

My conclusion, based on the evidence and the balance of probabilities, is that the minimum unit of displacement in a pre-jump is not less than a centimetre for it to be detectable with reliability even when assisted by visual recording without some means to confidently determine the time relationships and locations of the take-off toe and pole tips throughout the take-off and the initial portion of the first phase of pole support.

For a Petrov / Bubka defined “Free Take-off” where the take-off foot toe-tip breaks ground contact as the pole tip impacts the rear wall of the box the unit is the millimetre. Logic suggests that the time gap is zero but practically it is the minimum time possible that can be discriminated by the capabilities of the observer or measurement system.

Because of the speed with which such an event occurs the vaulter will only know that this event happened a very long time after it has occurred. The data suggests that the vaulter has advances well into the pole support phase of the vault, for at least 70 – 120 milliseconds beyond the toe off point in time, before it is possible to become aware of what occurred at the instant of take – off. Even then the vaulter is highly unlikely to become fully aware until he uses introspection to interrogate his kinaesthetic memory of the vault process after the jump has been completed. The method of introspection is notorious for its unreliability!

In the force time graph below if the impact of the pole tip was to occur within a millisecond of the vaulter’s toe tip leaving the ground and the pole tip had been in contact with the apron of the planting box some milliseconds prior to that instant then there is the minimum interference or interruption of the take-off motion that is feasible in real world practice. In the case of the real world force time graph of the pre-jump PSJ 1137, assuming all else remained the same, the pole tip would have to have contacted the planting box about 64 millisecond before the identified toe off occurred.

Pre jump final 2.jpg
Pre jump final 2.jpg (78.66 KiB) Viewed 8813 times


It is very interesting that this is just about the same time in the take-off ground contact that the amortization phase ends and the propulsion phase begins. It points therefore to a “Free- Take-off” as having to commence about half way through the ground contact time in order for the pole tip to have advanced towards the deepest part of the planting box and strike the rear wall within 1 to 2 milliseconds of toe tip leaving the ground.

I conclude that Agapit is once again correct in his statement with respect to an “ideal” free take-off” as advocated in the Petrov/Bubka concept.

Altius, on the other hand is being pragmatic, based his suggestion on empirical experience of how to achieve the “ideal free take-off”.

A little thinking about the empirical evidence I have provided will assure readers that if the “planting of the pole in the box” is completed before, about half way through the ground contact phase of the take-off, then the pole will be offering considerable resistance to the forward progression of the vaulter+ pole total system before the take-off point in time is reached.

Altius, suggests that in a pre-jump the height created at take-off is a matter of centimetres not millimetres.

This addresses the critical coaching issue of how to get the vaulter to execute a free take-off by timing the completion of the plant to coincide more closely with toe tip take-off. Practical experience shows that “taking –off under” actually encourages pre -bend pole loading, such that it resists the progress of the take-off and significantly lowers the pole ground angle.

Logically the point in time for completion of the plant to be coincident with the toe tip take-off requires the initiation of the pole tip planting box initial (and sliding) contact to occur in the propulsive phase of the take-off ground contact.

The time before toe tip take-off from the start of the propulsive phase of the take-off is in the range 50 to 60 milliseconds. This extremely short interval of time is beyond conscious control at any time by the vaulter during the entire ground contact of the take-off because the fastest known kinaesthetic reaction times to initiate an error correction response are in the range 70-120 milliseconds.

The time it then takes to complete the error corrective response must be added to this reaction time to determine the total corrective time involved in amending a motor act execution error. When the whole body is involved and in motion in which total body momentum is involved error amendment takes even longer again.

Pre jump 25.jpg
Pre jump 25.jpg (81.68 KiB) Viewed 8813 times


For the timing of the pole tip impact to coincide ( within plus or minus 1 to 2 milliseconds) with the take-off toe tip breaking ground contact the vaulter (a) must be operating in feed forward mode of motor action control and (b) make the decision to complete the plant well in advance of the take-off foot making initial ground contact. When operating in feed forward (motor skill open loop control does not use sensory feed back to guide and control the motor action sequence) mode of control it would, at best, take the vaulter somewhere between 300 to 700 milliseconds to recognise an error has been made and to amend that error.

This information makes it imperative for vaulters and coaches to recognise that any intentional focus on the take – off has to occur at a time well before the initiation of the plant is started.

It also implies that taking off with the take-off foot closer to the box than that required for the mathematically and biomechanically optimum location of the take-off foot on the runway beneath the top hand grip location will create greater amounts of effective energy transmission losses during the take-off.

Altius is pragmatically and practically correct. By encouraging the vaulter to execute a pre-jump, the take-off foot placement on the runway being exactly that required in a “free-take-off,” but with the difference that the vaulter attempts to be airborne slightly before the pole tip strikes against the rear wall of the planting box.

Evidence in the case study showed support for this to be the case.

The empirical evidence I brought into the discussion clearly demonstrates that when the observer has to rely on the evidence of their own eyes, even when assisted by normal speed video footage of pole vault take-offs, it is an uncertain and very unreliable means by which to attempt precise differentiation between a free or a pre-jump take-off.

Much higher video recording speed can only go part of the way to resolving the evidentiary problem for the reason that the planting box is usually obscured. It is also extremely difficult to film with just a single camera both pole tip and take-off toe tip and show them both in each frame captured during the take-off.

As promised Kirk you have my answer!

The question as to whether it is possible to execute a Petrov / Bubka type "FreeTake-off" by being even slightly "Under" is shown not to be possible in real world vaulting because there is always some resistance from the pole and greater energy losses incurred. Thus being a little further out from the ideal take-off location is a precursor to learning an effective "Free Take-off". The range in distance "out" from ideal take-off foot location is going to be very small. Perhaps in the order of 1-5cms at most !

Over to you and interested readers of PVP to hopefully bring any errors of fact or misinterpretation of the evidence I may have made.
Last edited by PVstudent on Sun Aug 25, 2013 12:20 pm, edited 1 time in total.
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Re: What is your correct takeoff point?

Unread postby Skyfly » Sun Aug 25, 2013 12:15 pm

This was an outstanding series of posts. Thank you for all the time and effort you spent to share this!

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Re: What is your correct takeoff point?

Unread postby KirkB » Sun Aug 25, 2013 2:07 pm

I join Skyfly in thanking you, PVStudent, for this outstanding series of posts!

Your last post summed it up very nicely, and answered my original query. Thank you! :yes: I was wondering when you would get there! :D Thanks!

I am not a skeptic of the pre-jump. In fact, in my day, I think I may have vaulted exactly as you describe. However, without any video proof (and certainly without any of the even more detailed measurements that you were able to acquire and expound upon for certain vaulters), I have only my (fading) memory of 1971-72 events to rely on.

In my posts over the past 6 years (and especially in my Bryde Bend thread), I have mentioned that I immediately knew that I would NOT have a good vault if I felt the tug of the pole prior to takeoff.

I also mentioned that a vaulter can never be precise enough on EVERY jump to get the perfect "free-takeoff" jump, just because of the variability in the stride pattern; the inability for the human eye to adjust the run to the perfect takeoff point based on distance from the box while running at high speed; and other environmental, physiological, and psychological factors that contribute to this variability.

I also mentioned in my Bryde Bend post that I felt (sensed - based on biomechanical feedback mechanisms - expecially TACTILE feel, but also a sense of TIMING) the need to jump/reach/stretch forwards at a rather extreme angle (much more extreme than any of my fellow vaulters) whilst I stretched my trail leg in a backwards and upwards direction after takeoff and before my downswing. I referred to this (especially the reaching forward with my top arm part) as "filling the gap", and I believe (now) that what I was doing was reducing the variability of each one-off jump by stretching and reaching whilst waiting (maybe only a few milliseconds) for the pole to hit.

I didn't do any of this with scientific measuring equipment, and I couldn't tell you how many milliseconds I'm talking about. We were rather particular about ensuring that the takeoff was at the "right" spot, but even there, we weren't any more precise than perhaps the nearest centimeter - maybe even only to the nearest inch. When you think about asking someone (not always someone with an eagle eye) to "catch your step", you can't expect much more precision than that - even today.

I suppose we could have used some sort of persistent tracer on the runway (like the plastercine used in LJ), but we weren't even THAT scientific.

I do have a question though, that has not been mentioned yet in this thread (altho I recall it being mentioned in other threads from time to time). What about audio feedback? i.e. The vaulter and/or coach (especially the coach, I suspect) hearing the thump of the pole hitting the box in relation to when the takeoff foot leaves the ground?

If you were to ask me if I used audio feedback, I could only give you a vague answer. I can only say that audio was only one aspect of what I call the "feel" of the vault. This "feel" gave me a sense of whether the "timing" of the vault was "spot on" or not. It sounds rather mundane to even mention this admittedly vague alternative to measuring the mechanics of the takeoff with more accurate equipment, but (a) if it works, the equipment needed to diagnose each vault-instance is readily available (the ears); and (b) that's all I had in my bag of tricks from back in the day.

My coach (Ken Shannon) never had the opportunity to "feel" my vaults in the tactile sense as I did - only I could feel the timing of the impact of the pole compared to when my foot left the ground, but he could certainly "hear" the pole hit. I don't recall ever discussing what HE thought of the timing though - based on HIS audio perception. Rather, the first question that he always asked me after each vault was how I thought the vault felt, and then a discussion would ensue from there.

I would be interested to hear from other coaches and vaulters whether they have been successful in using audio feedback? I think it goes without saying that today everyone uses recorded video feedback (watching vids immediately after the jump), but do you listen for the thump of the pole in the vids? Or do you reference back to the timing of the thump of the pole (outside of the vid)? Or?

I would also be interested in hearing what you think, PVStudent, from a scientific POV re audio feedback. Is there sufficient precision via this feedback channel for it to be reliable in classifying a jump to being "under", "free-takeoff", or "pre-jump"? Or not? I suspect "not", else you would have already mentioned it.

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Re: What is your correct takeoff point?

Unread postby PVstudent » Mon Aug 26, 2013 4:58 am

Kirk's question to me PVstudent.

“I do have a question though, that has not been mentioned yet in this thread (altho I recall it being mentioned in other threads from time to time). What about audio feedback? i.e. The vaulter and/or coach (especially the coach, I suspect) hearing the thump of the pole hitting the box in relation to when the takeoff foot leaves the ground?

If you were to ask me if I used audio feedback, I could only give you a vague answer. I can only say that audio was only one aspect of what I call the "feel" of the vault. This "feel" gave me a sense of whether the "timing" of the vault was "spot on" or not. It sounds rather mundane to even mention this admittedly vague alternative to measuring the mechanics of the takeoff with more accurate equipment, but (a) if it works, the equipment needed to diagnose each vault-instance is readily available (the ears); and (b) that's all I had in my bag of tricks from back in the day.”


The screen shots of the film editing program shows the still frame image recorded and its temporal coincidence with the sound track from the inbuilt microphone of the video camera used in recording the images. The red vertical red line indicates the location of the top right image of the vaulter that is coincident with the sound track.

Note the vaulter’s position in each screen shot.

Two facts, first the video can only have an accuracy of +/- 20 millisecond (+/- 1 video field) and two, the sound of the pole tip hiting the rear wall of the planting box will be heard a few milliseconds before the sound of the impact reached the camera microphone.

Within the limitations implied by the facts it is physically and physiologically impossible for the vaulter to hear the sound of the pole impact until airborne in a "free take-off".

Pre Jump answer sound question 1B.jpg
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Pre Jump answer sound question 2B.jpg
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Pre Jump answer sound question 3B.jpg
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The question of the use of auditory feedback by coach and vaulter is not the issue I was addressing.

The evidence I present above shows despite some uncertainty that both the coach and the athlete are relying on the feedback retrospectively in regard to real time of event occurrence.

I point out that the sound can only be heard some very small quantum of time after the causative event.

Therefore the information conveyed by hearing the sound can only be used to start to modify the vaulter’s action after another 300 – 700 milliseconds (fastest times recorded to start to correct error in complex human body motions) have elapsed before being physically able to start to amend any error that may have been recognised from the signal stimulus conveyed by the sound.

My practical experience is that both vision and sound assist greatly in improving the accuracy and precision with which the vaulter and coach, after the completion of the vault, can make the decisions as to whether or not the jump approximated their respective preconceived perceptual understanding of the timing of the pole impact in a “free and pre-jump” take-off.

The simple way to deal with the sound issue in real life action is decide after the take-off has occurred the answer to the questions:

(1) Did I hear the pole hit before, just as, or just after our Kinaethetic perception tells us we are off the ground in the case of the vaulter? (kinaesthetic reaction (70-120milliseconds) is faster that auditory reaction (150 – 180 milliseconds))

(2) Did I hear the pole hit before, just as, or just after I saw the toe tip break the ground contact when observed in the case of the coach? (Auditory reaction time is faster than visual reaction time (180 – 220 milliseconds)).

If the sound is heard before the take-off is felt or seen then the plant completion is too early for a “free take-off” to be possible.

If the sound is heard as the take-off is coincident with kinaesthetic sensation of take-off by the vaulter then the vault might be a “free” or a “pre-jump take-off”. If the vaulter hears the pole strike the rear wall after the kinaesthetic sensations of the take-off then the probability of having executed a pre-jump is high and the chance of the take-off being free is relatively higher.

For a the take-off to be a “free take-off”( ie the plant has been completed coincident with pole tip rear wall strike sound) the coach should clearly perceive that the toe tip had left the ground slightly before hearing the pole tip strike sound!

As the coache’s perception of the time interval separating the vision of the toe tip breaking ground contact and hearing the pole tip strike is subjectively assessed to have increased there is a higher probability of a pre-jump take-off having occurred.!

The decisions of the vaulter and the coach have to be accepted as qualitatively sufficient to correctly guess what actually happened in the take-off.

Experienced vaulters and coaches have sufficient qualitative auditory and visual perception discrimination to be able to recognize what has occurred from contextual Visual + Kinaesthetic + auditory information by the vaulter and the auditory + visual information perceived by the coach, For both the vaulter and the coach these processes are at the conscious level during learning to take-off and in learning to observe the take-off.

These essential cues become subconsciously involved in guiding the process by the vaulter and pre-cuing the coach in advance (ie feedforward control) of the critical events allowing automated perceptual processes to operate at faster recognition speeds during more skilful performance and observation of the take-off technique in elite pole vaulters.

This area related to use of auditory and other forms of sensory feedback or feedforward in the timing and learning of a complex coordinative pattern such as the “plant and take-off sequence in flexible pole vault” has an extensive body of accumulated research by scientists interested in motor control and the neurophysiology of motor action.

I believe this is outside the scope of the current forum which is focussed on the issues specifically related to the question “Is there a correct take-off in modern pole vaulting?”

Fascinating though the question to me is, and though I could have plenty to say on the science of the matter, I desist from going any further on answering the question posed to me because I believe it drives the discussion away from the original question.

My answer to the forum question, which I considered very carefully and conscientiously, is Yes there is a correct take-off in modern pole vaulting!

I thank members for their expressed appreciation for my efforts.

Could we, as discussants in this specific forum topic, please try to reach a consensus position and or highlight the major area/s about which more evidence based anwers are required before consensus can be achieved?

In this way most readers, particularly elite vaulters and their coaches, will be left with a clear picture of the current state of knowledge of the science and empirical evidence that underpins the art of perfecting the performance of the take-off aspect of the pole vault process.
The discussion could be summarised to point out clearly areas of agreement, areas of uncertainty and disagreement and give a consensus based set of guidelines to current best practice for achieving more effective take-offs by all practicing pole vaulters and coaches who follow PVP Advanced Section.

I am interested for all discussants to stay on the specific topic, so perhaps Kirk, you as the forum leader, could summarize the discussion after the “correct take-off forum” runs for, perhaps another 2 months?
Last edited by PVstudent on Mon Aug 26, 2013 9:13 pm, edited 1 time in total.
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Re: What is your correct takeoff point?

Unread postby KirkB » Mon Aug 26, 2013 4:26 pm

PVstudent wrote: ...
I believe this is outside the scope of the current forum which is focussed on the issues specifically related to the question “Is there a correct take-off in modern pole vaulting?”

Fascinating though the question to is, and though I could have plenty to say on the science of the matter, I desist from going any further on answering the question posed to me because I believe it drives the discussion away from the original question.

My answer to the forum question, which I considered very carefully and conscientiously, is Yes there is a correct take-off in modern pole vaulting!

I thank members for their expressed appreciation for my efforts.

Could we, as discussants in this specific forum topic, please try to reach a consensus position and or highlight the major area/s about which more evidence based anwers are required before consensus can be achieved?

In this way most readers, particularly elite vaulters and their coaches, will be left with a clear picture of the current state of knowledge of the science and empirical evidence that underpins the art of perfecting the performance of the take-off aspect of the pole vault process.
The discussion could be summarised to point out clearly areas of agreement, areas of uncertainty and disagreement and give a consensus based set of guidelines to current best practice for achieving more effective take-offs by all practicing pole vaulters and coaches who follow PVP Advanced Section.

I am interested for all discussants to stay on the specific topic, so perhaps Kirk, you as the forum leader, could summarize the discussion after the “correct take-off forum” runs for, perhaps another 2 months?

OK.

I have created the new topic re "Audio, Tactile, and Visual Feedback/forward re Takeoff" here: http://www.polevaultpower.com/forum/viewtopic.php?f=38&t=37519

On the original topic (in this thread), let's see if we can gain some acceptance (or dispute) of PVStudent's facts.

Do we agree that they're FACTS as opposed to THEORIES?

I personally agree, but what about all you skeptics out there? :confused:

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Re: What is your correct takeoff point?

Unread postby rainbowgirl28 » Thu Feb 06, 2014 4:04 pm

I know this is old, but PVStudent, thank you for the tremendous amount of time and energy you put in to posting all of that.

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Re: What is your correct takeoff point?

Unread postby willrieffer » Sun Mar 23, 2014 2:36 am

Okay...

Despite the breathtaking nature of PVStudents work, alas, questions remain.

1)There is some amount of time devoted to being able to spot such pre-take off events. I will advance something different as per Bubka. He, and those practicing that strategy did not always achieve what they were striving towards, the "free take off"! He as much says so, and while it is hard to see where they succeeded it is much much easier to see where they failed. That is foot contact coupled with pole bend. Further, I would contend that in Bubka's famed 93 skyride at the WC's it is very easy to see that the pole begins bending almost immediately as his take off foot hits the runway! And, uh, it did not seem to affect that vault negatively....And, well, Bubka's first 6.0 jump, well, if you look he actually effects his pole with a reverse bend at take off! I don't even know where to begin with that one!

2) That there is a vicious box force for vaults where the vaulter bends the pole should come as no surprise. The question is about the trade offs, some of which were addressed and some which I think were not. One is that on any free take off eventually the box still has to provide the necessary resistance that has to be there for the vault to occur and for horizontal motion to be turned vertical and that the moment it provides up the pole and against the vaulter still occur in a free take off vault. You cannot really "lose" energy in the system (or much sans friction/heat), only lose control of its direction. The trade off is that in the free take off the vaulter cannot add mechanical energy through take off leg drive into the system in addition to the kinetic energy where we must think that in both cases the kinetic energy, i.e. the speed of the vaulter is the same.

3)The other trade off is that as soon as the pole starts bending the chord is being shortened, which is the thing which drives this event. Is there a trade off? No doubt. Is it worth it? I remain unconvinced. I am also very dubious of the explanation of the arm forces for swinging on such a bend, that is that these vaulters have to "pull" themselves into a swing. I believe the effect is as for most vaulters regardless of take off style, they have to get their CoM back and down as soon as possible. I see no evidence that they in fact pull into a swing but do what everyone else tries to do. Press their shoulders back and create an action/reaction where they relatively move their COM back and the pole forward. Even in the case of the free vaulters I can see them working to slow the swing and store rotational energy in such a way that it maximizes their COM.

All of this, I tend to think, pales in comparison to whether or not a vaulter can effect their COM in the vault. I tried the free take off method when I first read about it in 82/83...and it was a nightmare. I could not do it as I could not get or keep my CoM where it needed to be. It was with the "free" take off method that I felt jerked at the hands by the force of the pole hitting the box. That my hips would initially shoot forward and then stall and drop. But then I tried and gave up on the double leg swing as well for the same reason...

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Re: What is your correct takeoff point?

Unread postby DLM » Sun Mar 23, 2014 11:23 am

I think I will weight in on this one. while my opinion is not based on science, it is based on observation as a coach. I am a believer in both a free take off and a per jump, for these reasons. first if you are causing the pole to bend by your action then you are under even if it is ever so slight and you are puling down on the pole with your top hand and or pushing with your bottom hand and your body is being loaded with undo force which can lead to injury over time, not only that if your leg is not jumping into your vault then you are leg is being used to stop your momentum and you are duping speed. in my opinion the main advantages in the free and per jumps are, first, reduced force on the jumper and second and probable the most important is that all thing being equal the higher you can jump that is get your top hand up before you lose any speed the easier it will be to role the pole. look at a pro basket ball player as they go up for a layup from the top of the key, its the same jump. It is not an easy thing to teach you can't just try it and then give up, it take time. How far out you can take off before you start to lose height and speed is based on each jumper combination of how fast they are and how high they can jump

willrieffer
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Re: What is your correct takeoff point?

Unread postby willrieffer » Sun Mar 23, 2014 8:10 pm

DLM wrote:I think I will weight in on this one. while my opinion is not based on science, it is based on observation as a coach. I am a believer in both a free take off and a per jump, for these reasons. first if you are causing the pole to bend by your action then you are under even if it is ever so slight and you are puling down on the pole with your top hand and or pushing with your bottom hand and your body is being loaded with undo force which can lead to injury over time, not only that if your leg is not jumping into your vault then you are leg is being used to stop your momentum and you are duping speed. in my opinion the main advantages in the free and per jumps are, first, reduced force on the jumper and second and probable the most important is that all thing being equal the higher you can jump that is get your top hand up before you lose any speed the easier it will be to role the pole. look at a pro basket ball player as they go up for a layup from the top of the key, its the same jump. It is not an easy thing to teach you can't just try it and then give up, it take time. How far out you can take off before you start to lose height and speed is based on each jumper combination of how fast they are and how high they can jump


It's obviously an outlook and system that have and continue to yield results. One of the best. It works very well for lots of vaulters. If you like it, if you believe in it, by all means keep using it.

What I'm pointing out is something somewhat different. Guys in this system, Bubka specifically, admits to the fact that they did not get the free take off all the time. That is they could not always, or in fact rarely got the timing and placement of the foot and free leap and thus missed the free take off, and still have monster vaults with foot down and pole bend take offs. Or, they got a lot of "bad" take offs that they worked into big vaults. And I'm not yet finding any evidence that when they did get free take offs it produced significant results. So it appears that they were coached to a certain ideal take off, but in fact made plenty of big vaults without achieving it. That begs the question, was their explanation, in particular in regard to the free take off, of their results correct? I don't think so....

Will

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altius
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Re: What is your correct takeoff point?

Unread postby altius » Mon Mar 24, 2014 4:14 am

[quote="willrieffer"]Okay...

Despite the breathtaking nature of PVStudents work, alas, questions remain.

1)There is some amount of time devoted to being able to spot such pre-take off events. I will advance something different as per Bubka. He, and those practicing that strategy did not always achieve what they were striving towards, the "free take off"! He as much says so, and while it is hard to see where they succeeded it is much much easier to see where they failed. That is foot contact coupled with pole bend. Further, I would contend that in Bubka's famed 93 skyride at the WC's it is very easy to see that the pole begins bending almost immediately as his take off foot hits the runway! And, uh, it did not seem to affect that vault negatively....And, well, Bubka's first 6.0 jump, well, if you look he actually effects his pole with a reverse bend at take off! I don't even know where to begin with that one!

Pity you did not study further or even bother to look at the inside cover of BTB2 -no I am not advertising -simply pointing out that your comment about the first 6.00m vault is patently incorrect - as anyone couldl see from that photo of that jump. He is clearly 10cm in the air the pole is straight and not loaded - how do we know that for certain - the right arm is still covering the ear.

Re the 'free take off '; clearly you have not bothered to read what Bubka himself said. What he 'as much says' is that he did not achieve 'a pre jump take off ' often, even though that was always his aim. But he usually had a free take off where the pole was not loaded before he left the ground. Of course you will find examples where he did not achieve this. When you are running 20 steps carrying a 5.20/10.4 flex pole at around .9.7 metres.sec in variable wind conditions that is certainly understandable, His winning clearance in 88 was a classic example -and that too was explained to me BY Vitali as we sat in the stands in Barcelona. Incidentally How many long jumpers have you seen hit their take off spot every time - and they not only do not have to carry a pole they can clearly see their target area form the end of the runway = can vaulters see the point where they are going to plant the pole at that point?

So I suggest you go back to your studies old son -better still go to Formia and talk with Petrov - even better discuss it with Bubka -you might learn something of value. You don't know enough to know how little you know - go away - you are dangerous!
Its what you learn after you know it all that counts. John Wooden

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Re: What is your correct takeoff point?

Unread postby grandevaulter » Mon Mar 24, 2014 9:29 am

altius wrote: as anyone couldl see from that photo of that jump. He is clearly 10cm in the air the pole is straight and not loaded - how do we know that for certain - the right arm is still covering the ear.

:yes:


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