Placement vs. Pressure

[PVstudent]

Some vaults by John Pennel
https://youtu.be/IhJbTHnt9UA

https://youtu.be/jo6Nqk4a5hM

https://youtu.be/Q3JWANR7lh4

Whilst the evidence is open to interpretation the key question posed by the originator of the thread in regard to this particular pole vaulter and the use of the bottom arm in attempting / not attempting to create space between the vaulter and the flexing pole to increase the potential amplitude of the trail leg swing can be specifically addressed.

Contributors might suggest other specific examples for discussion on whether or not the role of the lower arm is primarily to (1) increase the space through which the vaulter can swing and (2) act as a leverage point for the swing. The 2 points reflect my understanding of the central thesis raised in the first commentary of this thread.

At this juncture I will not make any comment pro or con the originator’s thesis.

I do have a set of comments I would like to make but will abstain from participation until the discourse gets directly on the topic by addressing specific shared examples.

Increasing reader awareness of the facts rather than producing reams of yet more opinion and conjecture on this seemingly intractable technical conundrum should be the goal of contributors.

Pole vault teachers, coaches and vaulters are keenly waiting for facts and principles of the arm actions in the pole support phases of the vault which will enhance their success and involvement in pole vaulting.

Opinions, ego wars, personal reconstructions of the past, abusive argumentation and ranting have defeated many previous attempts to cover this topic on this site in a sensible and rational manner.

This is an opportunity for the many wise, experienced and practicing coaches of pole vault to bring about some consensus even if only to identify what may or may not be relevant Facts of the Matter.

There are very many pole vault practitioners with vast resources of professional expertise such as engineers, physical scientists, research scientists in a variety of pertinent disciplines, sports scientists, surgeons, neuroscientists etc., who can help us clear up the science behind what is going on in the arm actions under review.

Similarly there are many highly credentialed pole vault coaches from all over the planet who could contribute their understanding and knowledge when focused on this issue.

For busy, committed people to give their time and share their expertise on PVP, especially in the Advanced Section discussions, the challenge for contributors is to present their perspectives as clearly as possible. Argument is what is expected when issues are controversial or unresolved. What is not expected or acceptable is confrontational argument attacking the person.

I am guilty of attacking the person in a discussion on this site and understand that it is extremely difficult to avoid doing so. Having made my confession I will give my best endeavors to not do this again but I suspect they won’t be good enough!

Please let’s get the topic on track, argue about facts if possible and let’s see if more people will make the effort to contribute for mutual benefit for everyone.

Readers if you want to contribute please do so as this issue is desperately in need of resolution.

[PVstudent]

Russian Pole vaulter 1960 national championship
https://youtu.be/PZDqqTYFfEY

Fred Hanson 17ft 1inch
https://youtu.be/HbXTvjHL1xw

Fred Hansen and Wolfgang Reinhardt
https://youtu.be/SW8FYTx6dQo

The 1964 Olympic Final Pole Vault: Fred Hansen and Wolfgang Reinhardt
https://youtu.be/jcVzZtqboQs

Bob Seagren & others 1968 Olympic Final
https://youtu.be/x6LPQSvw1m4

Catapole controversy Munich 1972
https://youtu.be/3EUjABT0dAo

Bob Seagren and Klaus Schiprowski
https://youtu.be/cvsVVxlhR_g

The videos above show some examples of elite level exponents of fibre glass pole vaulting of the 1960’s. The technical evolution in fibre glass pole vaulting has continued from the 1970’s through to the present time and Renaud Lavillenie’s 6.16m Indoor World Record.

The origins of the current enigma in regard to the role of the lower arm action arguably can be traced to the decade 1960 to 1970.

Wide Grips, low pole carry, across body large laterally deviated pole carry prior to the plant, “round arm” plant actions, take-off foot ground placement well forward under and in advance of the top grip hand location on the pole, low plant angles and conscious deliberate attempts to make the “heavy” and relatively stiff pole commence bending whilst the take-off foot was grounded and well before the vaulter took off in the jump were common practice and characteristic of elite vaulting in the 1960’s as recorded and observable in the footage referred to above.

Readers may find the video sources referred to worthy of observational comparison to vaulters from the decades 1980 to 2010. The re-emergence of the French dominance in Mens pole vault from 2010 to 2015 is also very revealing.

The technical developments in Women's pole vault technique from 2000 to the present illustrate the emergence of new strategies and methods facilitating the exploitation of the advantages of technological improvements in modern lighter vaulting pole weights, flexibility and performance durability and reliability.

[ADTF Academy]

Some vaults by John Pennel
https://youtu.be/IhJbTHnt9UA

Prime example of looking at the link between athlete and equipment. I never had the privilege of using the poles or being around the poles Pennel used. To compare what he was doing to the norm of modern age poles (depending on brand) is quite difficult. Look at the shape of the pole bend the bottom half doesn't bend very much, in order for the posture to remain and bottom arm fully extended the pole must be able to open up in the bottom half. This pole doesn't seem to have that ability. In this case maybe that was in fact a bottom arm that was straighter. Show a comparison to his competitors. Leading into impact his bottom arm does straighten completely out in an attempt I would say to do it. If you notice on impact he is not stable with his top arm slightly bent. Usually a sign someone is trying to focus to much on their bottom arm. So on impact the constant pressure of top hand and box isn't present so the pole isn't fully flexed from top to bottom and slack occurs. This is a whiplash effect that can lead to the normal fiberglass face appearance.


I would have to say my vote is he was trying to and did have a straighten bottom arm for this generation of a vaulter, but used it effectively to still jump very well. Many who try to straighten the bottom arm do it wrong and become less effective pole vaulters.


On a side note its so fun watching vaulters like Pennel. 17' + is still a great jump today and he did it on beyond outdating equipment. What you see as a coach or what athlete thinks they are doing isn't always the correct answers. Its the linking of the two and getting the outcome desired visually by the coach and mentally by the athlete.


Does anyone know Pennel's grip? I am sure I saw it before just can't think off top of my head what it was.

[willrieffer]

From a purely physics perspective we can form an analysis of the event that takes the pole out of the analysis and simply resolves its forces into x and y forces. Once one takes this perspective then what is left is the energy relation of the CoM path where its horizontal or x velocity is relative to its potential energy or y position.

In short what often generally matters is the CoM path and how its early rate of change is managed. IF it rises too fast the vault stalls. The lead arm can have regulatory properties directed toward the CoM path that is to keep it in a lower trajectory by regulating the swing angle and speed. As a property of pendulums, free swinging shorter vaulters will swing forward faster than taller ones where swinging forward faster in time increases the potential energy rate of change by allowing the CoM to move up too fast in time. One of their routes to prohibit this is lead arm action, basically holding the CoM back and down in time.

The "cost" of this action is in swing energy as swing speed. They are purposefully slowing the swing rate to conserve energy in the early vault transit.

There has been comment made on this in regard to "continuation of motion" which I'll try and address here. IF you are using the PB method and trying to maximize swing energy then any "blocking" of the swing would have to be considered "poor" technique as once the swing is inhibited in some way, slowed, then you are going to develop less swing speed and then energy. But IF you're vault method is one of conservation of energy, a low drive vault, with swing braking, then this analysis doesn't hold. Lavillenie doesn't do anything that looks like he's working into a big fast PB/Bubka type swing...because he's not. He's conserving energy and pole momentum in other ways. So there is no way to really combine these two methods in the post take off.

In part the big energetic swing of the PB model (which sees greater energy generation from longer and generally heavier vaulters) is necessary to keep the pole moving forward in the mid vault as the elevation of the take off angle has effect on the x and y velocity vectors where basically there is a cost in horizontal velocity at take off.

In short, longer vaulters are more attuned to the PB model than short ones and since they naturally "free swing" slower than short vaulters approach a point where there is little to no need to regulate the swing speed with arm action. Short vaulters face a multifaceted problem in that they generally start with a lower CoM, lower pole angle, and a problem that their "free swing" rate is faster, thus you see them use the lead arm for swing speed regulation. Their one advantage, which is the same as for short gymnasts, is that they have better leverage to adjust their swing speed and/or "muscle" to invert or some tuck position.

Much of this is related to the scale of the vault and the distance from the take off to switch point as well as the vaulters height, reach height, speed, etc. Young vaulters with low grips and short transits (where the transit is the distance from take off to the switch point of the pole) basically do not have or need a "drive" phase in relation to their need to invert and so generally have a need to "speed" the swing to cover and for which any "blocking" or swing speed regulation from the front hand is highly detrimental. "Pole loading" is really swing speed problem (and where the Japanese now have built a pole vaulting robot that jumps higher by "pole loading"). This is shown very well and explicitly in Joe Dial's "Vision of the Vault" video with its extensive video documentation of the evolution of his vault. Early on, as a very young vaulter he vaults quite well with a bent lead arm having to cover a shorter transit, but over time and in necessity of getting on longer poles and crossing the transit he has to learn to regulate his swing speed by use and extension of the lead arm.

hope that helps

[grandevaulter]

From a purely physics perspective we can form an analysis of the event that takes the pole out of the analysis and simply resolves its forces into x and y forces.

big fast PB/Bubka type swing...because he's not. He's conserving energy and pole momentum in other ways. So there is no way to really combine these two methods in the post take off.

More scientific and analytical terms and empirical evidence produced by Will.

Much of this is related to the scale of the vault

Well you finally considered scale

reach height,

You actually read my posts.

n short, longer vaulters are more attuned to the PB model than short ones and since they naturally "free swing" slower than short vaulters approach a point where there is little to no need to regulate the swing speed with arm action

Nicole Buchler is 5' 4" and uses the P/B. There are taller female vaulters that do not use the pre jump and long sweep leg.

Japanese now have built a pole vaulting robot that jumps higher by "pole loading").

That did it, you've completely won me over with the robot. That is much better than the NASA and MIT cut and pastes that you don't understand or are able to effectively describe.

[willrieffer]

GV analyze this problem.

We have two identical masses moving at the same speed perpendicular to a gravity field on a frictionless surface and in a vacuum (so that we can ignore friction losses). At the same time the both encounter horizontal planes one at 5 degrees and one at 30 degrees. Describe their motion (in the most general way) and resting positions and energy states. If you can. And if you can this will illustrate why the CoM path is important in a gravity field and to vaulting.

I know why the high path has possibilities, too. It simply has to do with the pole angle in time and the braking force it exerts, but in fact the physics explanation for this is much more difficult per the example above which is that that method has to provide its trade off for intentionally slowing its horizontal velocity by increased take off angle. But its why in the straight pole era vaulters would simultaneously both try to jump into the vault to increase pole angle as much as possible while then still trying to keep there CoM as low as possible, often with a double leg hang. Because the braking force for stiff poles at low angles approaches effectively the infinite. Flex pole vaulting changed that necessity drastically, so there was opportunity to either strive to keep the CoM accelerated in the low path, or to still try and alleviate pole braking in the high path.

But this divide is why you can't critique a vaulter using one method by the other. You can't critique Lavillenie by Bubka and the PB method or visa versa. It doesn't work as the advantages and trade offs they are using are different.

GV its funny. You never really address anything I write about directly but just try to use "authority" to "make fun" of me. I work with vaulters all the time to results. I've got the #3 soph girl in MO and #8 boy (and where we had to spend two weeks trying to get poles for him). This means my kids are up against ones vaulting year round for Cooper, as well as ones working with Attig, and training in AK. My kids don't vault year round. I get them for spring track and that's it. And yet I expect them both to be on the front page of Milesplit by grade rankings. I expect the girl to be somewhere over 10', and the boy to approach 15'. I expect in the next couple of years to have a good shot at having the class champion for boys and girls in a single year. And I just got up off the couch a couple a years ago to do this. Coaching this event isn't really that hard. You just follow examples. Understanding it, the physics, that's hard...

[grandevaulter]

GV analyze this problem.

I'll give it a whirl.

We have two identical masses moving at the same speed perpendicular to a gravity field on a frictionless surface and in a vacuum

Got it.

At the same time the both encounter horizontal planes one at 5 degrees and one at 30 degrees.

Buzzzzzzzz Whrrrrrr, Click Click Click Click. And the answer is:............ If they are moving "perpendicular to the gravity field, it doesn't matter what the angle of the plane they encounter, they are both equal. Perhaps we could try this problem without gravity at all or make both objects parallel to the gravity field.

If you can. And if you can this will illustrate why the CoM path is important in a gravity field and to vaulting.

Bzzzzzzz whrrrrr bzzzzzz click click, chirp chirp, This does not compute.The information provided to complete this analysis in invalid.

GV its funny. You never really address anything I write about directly but just try to use "authority" to "make fun" of me.

I've always addressed what you write about Will, most of it doesn't have anything to do about pole vault though. I'm glad that I'm now considered an authority, but that may just be a figment of your imagination. I just use common sense combined with a bit of humor.

Coaching this event isn't really that hard. You just follow examples. Understanding it, the physics, that's hard...

Some things may be best left to the Japanese robot.

I'm still waiting for you to answer Coach Strawmans story problem regarding Stickman the one arm pole vaulters dilemma of whether his feet or hips reach 12 O'clock first.

[willrieffer]

This is one I'm coaching. This was taken early last season. He was a freshman. I'd been his only coach. He missed half of his 8th grade season with an ankle injury suffered in basketball. So at the time I'd spent maybe 3 months total working with him.

Does this "stickmans" hips look good to you?!?!?

Look,

On one side I have you following me around PVP and deriding everything I post. Says something about your psychology mostly, but just to let you know.

On the other is decades of judgement given me by the education system. I maxed the Stanford Binet IQ test in 3rd grade(IQ around 170). I scored in the 99th percentile on every test I've ever taken in grade school or high school. I got a perfect 36 on the ACT Science and a 35 on the Math (I had to leave early to both run for and throw a TD pass in a football game). I have almost 180 credit hours in math, science, and education.

And you want to tell me I don't know what I'm talking about. It's funny. Hmmm. Should I choose you or the tens of teachers, professors, standardized tests, and accredited schools and Universities?

When the gravity vector points down, the horizontal is perpendicular to it. Or, try again...

[willrieffer]

Vault Physics – The Vertical Line and Potential Energy Curves

My name is William E Rieffer. I vaulted at Ohio State and while there studied physics.

I find what I call the “folk” physics of the pole vault to be littered with problems. I took me six years of studying the system to hopefully rectify that. The vault is dominated by potential energy concerns and curves.

I'm going to start with an argument to illuminate our situation followed by two tangible scientific demonstrations that only take a stubby and a roll of athletic tape to make my point.

Argument

Facts – Flex poles lose some amount of energy as heat. The amount is small, usually around 2% or so. Still, this is energy not recouped as max potential energy or height. Straight poles, because they don't take on significant energy as flex, don't lose significant energy.

The argument then follows. IF flex poles lose energy and straight poles don't then we should use straight poles to jump higher because they don't lose energy.

The facts in this argument are true. The logic is sound. Yet the resultant claim is one that any vault coach knows isn't the case! Why? Because of all the science left out of the argument. There are many arguments made about the vault that are faulty in this way because of what they leave out. And most of that is because they do not consider potential energy changes and curves per the vault.

1)Potential Energy and the Vertical Line

Take the roll of tape and the stubby. Roll out one or two feet of tape and leave it attached to the roll. Attach the tape to one end of the stubby. Place the stubby at an angle modeling the pole takeoff angle. The tape and roll act to model our vaulter with the roll approximating the center of mass of the vaulter. The roll should settle into hanging straight down in accord with the vertical line of gravity. This is the resting state equilibrium where energy and potential energy are at their minimum. Now slowly rotate the pole forward as with the vault. Notice that we have to push the pole because we're changing the potential energy of the system by moving the roll of tape, our center of mass, up. Now even though the pole angle has changed the resting state equilibrium still presents the roll hanging right under it's attachment to the pole (the vaulters “top hand”).

Now stabilize the stubby and push forward on the roll of tape. Since we have constructed a pendulum to displace the roll as center of mass we have to push energy into the system as the roll in it's pendulum motion is curving up to a higher potential energy state.

This analysis holds true if the energy is coming in the form of the kinetic energy of the vault approach.

In the immediate post takeoff there are three energy states. The residual kinetic energy state per velocity and mass. The energy now in the bending pole. And the changing potential energy as the vaulters center of mass rises. These three values extend from the initial kinetic energy at takeoff and cannot be immediately changed. In order to generate energy through force you need to have something to push on. Later, the vaulter can push the pole against the ground and increase energy, here there's nothing to push against to add energy.

So we are looking at a three variable problem that can't exceed the starting kinetic energy total. Thus if the vaulters center of mass moves up, there's less energy in either kinetic energy, or pole elastic energy, or both. Thus if the vaulter keeps their mass under the top hand they will have more pole energy and/or more kinetic energy/velocity.

The most important line in vault is the vertical line of gravity through the top hand.

Rocket Science or “Wobble”

2)Let's go back to the stubby. Balance the stubby on your palm. Now push up vertically on stubby. One of two things will happen. A) The stubby's center of mass will be closely lined up with gravity through your palm where you are exerting vertical thrust. If so then the stubby will fly skyward like a rocket. Or, B) The stubby's center off mass will be off from the vertical line of gravity through your palm and the stubby will “tumble” or rotate as you push up and will gain very little altitude. Thus, what makes a vaulter finish well is lining up their center of mass on the vertical line of gravity through the top hand.

And like the beginning we again see that the most important line in vault is the vertical line of gravity through the top hand.

To take it a step further the further the vaulters center of mass is displaced from this line over time(almost always forward of it), the harder the vault becomes. Or, nothing good happens in front of our line.

Answering the Questions

Using this framework we can easily and concisely address many questions about technique and other issues.

Getting “Stuck in the Bucket”

As newer vaulters find out nothing good happens when they get their hips and thus center of mass forward. Gravity is pulling down on the hips. If they haven't set up a good swing or lack strength they get stuck. This is compounded by the fact that if their hips were back under the top hand gravity would be providing a vertical compression force on the pole. Since they are forward and there's less compression on the pole the pole will go into recoil earlier and faster. And the vaults over.

Launder and Gormley once emphatically pointed out to me Bubka's highest rotational rate as measured by the IAAF. But they then couldn't tell me why it was good. Now I've explained it. He spent less time out in the “bad zone” in front of the line of gravity. The vault is a game of wait and hurry up.

The Leading Hand

So what does the leading hand do? Well it's in the unique position to be in front of the vaulter and vertical line so that it can be used to keep the center of mass back closer to being under the top hand. If punched or locked at plant it can be used to keep the center of mass back. I should mention that this is a very brief moment of impulse force right at plant/takeoff. I routinely see people pointing out much later in the vault the nature of the arm. Well, as soon as the vaulters legs start to rise they are now lifting their mass against gravity and generally the arms will be “pulled” straight. This is significantly after the point where the left arm can influence the center of mass placement.

Remember our three variable problem? When the hips are kept back closer to the vertical line it flattens the initial potential energy curve meaning there is more energy for the pole and residual kinetic velocity. Effective use of the leading arm results in more energy being directed into the pole at the TOP hand. These things are mutually beneficial. More energy into the pole is more bend and more energy to recoup later as vertical thrust. More velocity means more penetration.

Premature Rowing

Premature Rowing is bad simply because its forcing the center of mass up and forward prematurely. It impacts the potential energy curve negatively. Less energy goes into the pole and it slows faster. The athlete doesn't want to engage the shoulders before they have swung through and are lifting their center of mass. Wait and hurry up.

Other Considerations

The vault is dominated by potential energy concerns. Rotational dynamics is dwarfed by potential energy considerations.

Let's imagine we have a spaceman in a rotating space capsule. Outside on the capsule is a very very long pole pointed such that if the spaceman climbs it, he will lengthen the his distance from the axis of rotation changing the moment of inertia of the system causing it's rotational speed to slow. However, he is neither adding nor detracting from the systems energy state. Friction-less, it will keep rotating forever. If we add a plane of the crossbar to this system the spaceman will ALWAYS reach the plane.

What does effect and slow the vault system is the change and rate of change of the potential energy value. Vault is a bit like going up a hill in a car. Unless you step on the gas and add energy the car will stop. Most fail vaults, stalls, are for the reason that the athlete turned the potential energy curve up to fast, or likewise wasn't able to hold it down well enough, and like a car without gas they slow and stop.

The invention of the flex pole, while we can say it changed the rotational dynamics of the system, what it actually did was that bending poles allow a lower potential energy curve. The athlete stays closer to the ground with the benefits brought forth before. Lower potential energy value, higher residual velocity and/or pole energy state.

Parabolas

Any unpowered and liftless object is going to have its flight path conform to a parabola. This applies to vaulters when they leave the pole. Now there are low flat parabolas and high skinny parabolas. It should be obvious that vaulters want, in the end, high skinny parabolas that conform to the crossbar or has it's peak on or very near the crossbar. This is again a potential energy trajectory the one the vaulter needs to steer themselves and their center of mass towards. A parabola is mirrored. The vault isn't completely mirrored as a parabola until exit from the pole. A high skinny parabola is going to be closer to the plane of the crossbar. Thus the need for “penetration”. Again we're back to the three variable problem.

An interesting video showing this is Joe Dial's 5.96m jump in Norman. Joe enters at around 18' and clears easily landing well into the coaches box. Next, ~18' 6' and again he lands well into the coaches box. But at 5.96m he knows he needs to “skinny up” his parabola. He clears and lands in front of the coaches box just off the bevel.

Do I Dare?

When I started coaching I read everything I could get my hands on. What I found were just glaring physics mistakes.

The Petrov Bubka model

I would read that unless you used the free takeoff and jumped like Bubka you would “lose energy into the plant box”. This is, per the laws of physics and thermodynamics, wrong. The box doesn't move, therefore it can't take on kinetic energy. Is there some heat buildup with tip strike and friction? Yes, but the amount is certainly so small as to be insignificant particularly in a focus on mitigation. There were other things. Bubka admitting he “did not get the free takeoff today”, and yet still jumping high. At '93 Worlds I don't think he gets the free of either of the two bombs he launched there.

Of course now we have Mondo who doesn't get on the pole like Bubka, Mondo not doing the FTO and being routinely under. He doesn't swing like Bubka. And he doesn't exit the pole like Bubka. What he is is faster than Bubka and can take a big pole, drive it forward, and get his center of mass lined with his top hand and the vertical line of gravity.

Lavillenie had excellent form per my analysis. Punch the left. Keep the hips back. He also dropped the right leg lowering his center of mass, while also reaching his left far behind moving his center of mass, you guess it, towards our line.

One last thing. The “pole chord”. Well, if someone is talking about the pole chord they're wasting their breath. It doesn't mean anything. IF the swing isn't regulated by the hands the vector engagement that pulls the pole forward happens at around 45 degrees from the vertical which will extraneously coincide with the chord at some point as the athlete swings through. Likewise I've seen comments that Bubka's famous “negative invert”, 'lined up some part of his body with the pole chord'. That's mere coincidence. What it does is puts his center of mass in line with the vertical line of gravity through the top hand.

I've been a coach at Eureka HS Missouri for a decade. I've had kids the MO state meet every year but the first one when I transferred to Eureka from Grandview Hillsboro where I had multiple All State Vaulters. I coached many notable vaulters at Pole Vault STL until I retired from there as it got too painful on my body.

William E Rieffer

Dance GV Dance