Is Pushing with the Bottom Arm Good or Bad?

[powerplant42]

He's only talking about the take-off...

[vaultman18]

My quandry is that Altius says "drive UP through the pole" (which is in a "pushing" direction) whereas Agapit says "pull". How can both of these be true? Could it be that Altius is referring only to "young vaulters" and Agapit is referring only to WR contenders? Or is it a question of timing? Could it be that Altius is referring to only the moment of takeoff, and Agapit is referring to the moment AFTER takeoff?

They are both True. And I believe you have answered your own question.
For a perfect vault I feel that the Plant, Take-off and Swing cannot overlap. Think in terms of the "continuous chain".

[PaulVaulter]

Yes you need to push, but only for a very small amount of time and only with a small amount of force.

From an engineering stand point, if you assume the pole to be a column and to bend it, what we need to do is buckle it (vast simplification but sufficient for my point I hope). This can be achieved by applying a force directly down the pole greater than the buckle strength of the pole (force applied by top hand down the pole), this will be a big number for a big pole. What we can also do is apply a much smaller force at right angles to the pole, maybe 40cm from the supported end (bottom arm push with standard grip width). All this force is doing would be to create a small initial curvature to the pole making it a lot easier for our longitudinal force (that by our top hand) to continue the force and create a large bend. The bigger the bend in the pole, the less force is required to continue it bending. This is why they started pre-bending poles, it means the pole is not dead straight and greatly reduces its buckle strength making it a lot easier to vault on and bend properly. What we can then do is introduce a slight further pre-bend with our bottom arm as we begin to apply force with our top arm (I am not talking lock and block, just a slight push).

As far as all this is concerned, anyone who applies no force whatsoever with the bottom hand is losing A LOT of energy at the moment of pole contact with the box by trying to compress a (nearly) straight pole. Anyone who continues to press after this point is wasting there time as it doesn't matter how strong you are, the forces you can apply with your bottom arm are nothing compared to those going through your top arm from you run x weight x swing speed etc.

Basically driving both arms upwards is probably a sufficient enough cue (high fives Petrov)

Anyone who understands what i'm getting at and is capable of explaining this in a better way please do so. I suck.

Thank you please

p.s. if anyone actually wants to do the maths, I have pole stiffness numbers and longitudinal forces, just don't know how to do column buckling for a varying stiffness pole. My guess is we're looking at about maybe 50N of force with bottom arm compared to 900N from the top arm at impact.

[KirkB]

Yes you need to push, but only for a very small amount of time and only with a small amount of force. ...

Hmm ...

Paul, I appreciate you bringing this particular possibility up, and I appreciate you trying to explain this scientifically. We can all use more of that!

The theory that the pole begins (at the instant the pole hits the box) as a column that can't bend without a sideways buckling force is sound, I think, PROVIDED that the pole is a perfect column that requires a "buckling threshold" to be met before it will bend.

In my experience, EVERY pole has a prebend, thus a propensity to bend - always in one certain direction. In my thousands of vaults, I have not hit the problem of the pole being a perfect column. If I had, surely it should have given me a funny jolt when it hit the box. I felt no such thing - not once - and I think that's because the pole is NOT a perfect column. And I'm quite certain that I NEVER pushed or pressed (at least not purposely).

I have (on rare occassions) felt the pole bend IN A DIFFERENT DIRECTION than what I intended - when I didn't grip exactly in line with the prebend. This leads me to believe that the prebend masters the destiny of each vault, and that if - on rare occassions when the pole hits the box - the pole acts like a perfect column (i.e. it's PERFECTLY straight) then I would have felt a funny jolt from that. I did not - ever.

Other people's experiences may be different. After all, if you ALWAYS push, then you wouldn't know if the pole is bending because of (a) your push, or (b) because it would bend anyways - since it's not a perfect column ... would you?

What I don't understand is that you agree that poles are already manufactured with a prebend, yet you suggest that an additional sideways force is STILL necessary. Why?

We have several pole manufacturer reps cruising PVP, and lots of coaches/athletes with excellent pole technology knowledge. Perhaps one of them can shed some light on this theory? I'm particularly interested in knowing whether the test harnesses set up to bend poles apply a sideways force to initiate the bend or not. And why, or why not?

Finally, regardless of whether the initial push is needed or not (the main issue you raised), we definitely agree on this:

... Anyone who continues to press after this point is wasting their time, as it doesn't matter how strong you are, the forces you can apply with your bottom arm are nothing compared to those going through your top arm from your run x weight x swing speed etc.

If you continue to press, the best that can happen is that you'll bend the pole a BIT more, at the expense of slowing your swing down A LOT.

The worst that can happen is that you'll kill your swing so much that you'll stall out and miss the bar ... and the pit!

Kirk

[powerplant42]

Yes you need to push, but only for a very small amount of time and only with a small amount of force. ...

Petrov says both hands push up all the way! It is definitely not locking out, but it is a DRIVE where the bottom arm can help push the pole UP at take-off and will ultimately become straight due to the pole being bent. This was not a problem for stiff vaulters because their hands were together, acting as one! Would you rather push a pole (any pole) by jumping into it with one hand or two!?

[vaultman18]

Yes you need to push, but only for a very small amount of time and only with a small amount of force.

I think we covered this a while back with TM and it was finally determined that the bottom hand is not need to bend the pole. And the column theory did not hold. I will try and find it and post a link.

[vaultman18]

http://s43076.gridserver.com/forum/viewtopic.php?f=38&t=11698&sid=8fa6e2d0216234eeb4e85ba867c76937

This is the link to the the other thread. The thread is the "We are Doomed, Repent" by agapit. Everyone interested in the debate we are having now should click on the link above and read everything. Agapit is very clear no PUSH not even a little.

As I recall now the "Doomed" thread was taking place just prior to Roman coming to my house and just after. I also recall Alan and Roman talking for a few hours about the bottom arm and its role. And then Roman and I talking about this until early in the morning and it all becoming very clear to me.

[PaulVaulter]

Im not saying the pole is perfectly straight, I know there is a pre-bend.

I'm not saying you NEED a force at right angles to the pole, just that this force would need to be a lot less than a longitudinal force to initiate the bending process.

The pre-bend means that a longitudinal force however large creates a bending moment in the pole, the lever length being perpendicular distance from pole to imaginary pole chord, i.e. 3-5cm at most?

The bottom arm driving upwards creates a bending moment about the top hand, so although the force applied is lower, a lot lower (unless you happen to be french) the moment arm is equal to the width of your grip i.e. 40cm therefore force needs to be 8-13 times lower to start bending process. How about being french, grip 60cm wide and get 12-20 times more bending from your bottom hand.

It'd be best to draw some pictures I'm sure, but whatever.

I'm not saying you need to push with the bottom arm, but a small upwards driving force just as the pole contacts will initiate a slightly larger initial bend in the pole (like having a larger pre-bend but without awkward carry and plant issues), giving you a larger moment arm for your longitudinal force to act on intially, thus larger bending moment, thus larger bend. It should basically make for a smoother transition of speed into the take-off.

The longitudinal force will have a maximum value for each person depending on there take-off speed, it will also depend on their weight swing speed, strength and probably other things.

You can bend a pole with no bottom arm, you get a smoother transfer of speed and thus energy if you do.

I accept that I'm not explaining very well, I also accept that some won't agree with me. I guarantee you I don't push throughout the vault with my bottom arm though, I drive both hands up at take-off and just let it happen, if you ask anyone I train with, they'd swear i actually like the taste of carbon fibre, I don't, it tastes bitter, a bit like failure.

If anyone wants me to explain further, I will do but I can't promise I'll actually be able to make it any clearer

Seeeee ya later

p.s. I'm not racist against french people, I love Pepe Le Pew

[powerplant42]

Take any flexible pole... Grip at the top, and prepare for pole plant (about to go to take-off foot). What is happening to the pole?

[golfdane]

Having reviewed (again and again) the Isinbayeva training session on BTB2: Isi keeps the tip of the pole clear of the ground when doing plant drills. I encourage my athletes to do the same, but this pressure/resistance/bracing should IMHO only occur at take-off. Though poles aren't perfect columns, is the initial bend facilitated by this.

[PaulVaulter]

Take any flexible pole... Grip at the top, and prepare for pole plant (about to go to take-off foot). What is happening to the pole?

I don't understand what you're getting at? the pole is pivoting about a point about half way down ideally. Tip dropping hands driving up.

Having reviewed (again and again) the Isinbayeva training session on BTB2: Isi keeps the tip of the pole clear of the ground when doing plant drills. I encourage my athletes to do the same, but this pressure/resistance/bracing should IMHO only occur at take-off. Though poles aren't perfect columns, is the initial bend facilitated by this.

This is what I believe. Anyone seen the pole test machine they use at Gill? the pole is forced into an larger initial pre-bendfirst before the weight is dropped on it, this gives a more efficient transfer of enrgy into the pole because the initial moment arm is bigger. You can see it in the video about the weave poles at www.gillathletics.com/weave

[powerplant42]

I don't understand what you're getting at? the pole is pivoting about a point about half way down ideally. Tip dropping hands driving up.

The pole is bending... Not because the hand is pushing IN, but because it is pushing UP (or at least not allowing the tip to drop without resistance). You will often see jumps where the pole is obviously bending before pole-strike.