Push off

[Pogo Stick]

In literature push off is the main indicator of jumping efficiency. Here is a list with 6m club list sorted by push offs looks like this:

Code: Select all

Name   Height (cm)   Push off (cm)
Tim Mack   188   121
Sergei Bubka   183   117
Tim Lobinger   190   117
Jeff Hartwig   194   115
Danny Ecker    193   115
Jean Galfione    184   115
Igor Tradenkov    190   113
Steve Hooker    187   113
Rodion Gataulin    190   112
Dmitri Markov    181   111
Okert Brits    196   111
Maxim Tarasov    194   110


Absolute push off numbers can hide part of story. To compare jumping efficiency, it will be better to observe push off related to vaulter's height. Obviously taller vaulter has longer arms, and for the same grip and same bar height his hips and COM are closer to bar.
Both Brits and Markov have push off 111 cm, but Markov is 181 cm tall, Brits is 196 cm. Who has better push off and how to calculate normalized push offs?
At the takeoff your top arm is straight up, fist is gripping the pole. Take the measure tape and write down how high you can reach in that position. Then measure height of your hips from the floor and write it down. You will find that your hips are approximately in the middle between floor and your fist. So if your can reach 230 cm with fist, your hips are at around 115 cm.
At the clearance, when your upper hand release the pole you got same position, except you are upside down. For the same grip and same bar height if you are taller than Markov, your hips will be 0.5 cm closer to bar for each 1 cm of height.

I recalculated push off values by using Markov as the reference (he is the shortest 6m club member - 181 cm). Here is an example:
Brits is 196 cm, Markov is 181 cm. Brits is 15 cm taller and his hips are approx. 7.5 cm higher. For the same grip and same bar height, Brits needs 7.5 cm lesser push off to clear the bar. Or vice versa, Markov needs 7.5 cm bigger push off to clear the same bar. Both have 111 cm push off, so Markov's push off related to his body height is 7.5 cm "better" than Brits.
Here is a table with normalized push offs:

Code: Select all

Name   Height (cm)   Push off (cm)   normalized push off
Tim Mack   188   121   118
Sergei Bubka   183   117   116
Jean Galfione   184   115   114
Tim Lobinger   190   117   113
Dmitri Markov   181   111   111
Steve Hooker   187   113   110
Danny Ecker   193   115   109
Jeff Hartwig   194   115   109
Igor Tradenkov   190   113   109
Rodion Gataulin   190   112   108
Okert Brits   196   111   104
Maxim Tarasov   194   110   104


Tim Mack is the best, Bubka is second. Brits and Tarasov are at the bottom of the list.
What do you think?

[altius]

What I think, is that the statement, " push off is the main indicator of jumping efficiency." is not true .

[KirkB]

Pogo, while you make a good point, and you're mathematically correct, you should not lose sight of the more important aspects of the advantage of a taller vaulter over a shorter one - in the takeoff and swing. That extra 3 inches at the top is just a little icing on the cake.

Your math gives a 7 cm (~3") advantage to Brits over Markov at the top. But at the bottom, the 14+ cm advantage that Brits has over Markov is worth far, far more than that! I don't know how to weight these 2 disparate factors, but the angle of the pole on takeoff AND the extra leverage during the swing are significant advantages. (Temper that with generally more awkward gymnastic abilities of taller vaulters.)

Oh ... are you aware that if they were in a 100m race, Brits would have a 2 cm advantage over Markov, since in the starting blocks, he's already leaning closer towards the finish line? And then he gains another 2 cm over Markov by leaning into the tape!

Pogo, there are many, many things that you can do during your vaulter BEFORE you pushoff that can more than make up for this 3". Things that will add over a foot to your vault! I'll teach you some of them!

Kirk

[Pogo Stick]

What I think, is that the statement, " push off is the main indicator of jumping efficiency." is not true .

What else will be main indicator of efficiency? Grip? Pole flex? Bar clearance? All together?

[Barto]

In my opinion...

The main indicator of vault efficiency is the ratio of grip height to time it takes the pole to travel to perpendicular.

Chew on that for awhile...

[Pogo Stick]

In my opinion...

The main indicator of vault efficiency is the ratio of grip height to time it takes the pole to travel to perpendicular.

Chew on that for awhile...

Very interesting and very easy to recording - all you need is measuring tape and camcorder! Higher grip shorter time means better score (g/t).
Both parameters includes vaulters gymnastic and athletics ability - takeoff speed, swing radius and speed, strength, timing, etc. I like it! Do you have any numbers?

[Pogo Stick]

Pogo, while you make a good point, and you're mathematically correct, you should not lose sight of the more important aspects of the advantage of a taller vaulter over a shorter one - in the takeoff and swing. That extra 3 inches at the top is just a little icing on the cake.

Your math gives a 7 cm (~3") advantage to Brits over Markov at the top. But at the bottom, the 14+ cm advantage that Brits has over Markov is worth far, far more than that! I don't know how to weight these 2 disparate factors, but the angle of the pole on takeoff AND the extra leverage during the swing are significant advantages. (Temper that with generally more awkward gymnastic abilities of taller vaulters.)

Oh ... are you aware that if they were in a 100m race, Brits would have a 2 cm advantage over Markov, since in the starting blocks, he's already leaning closer towards the finish line? And then he gains another 2 cm over Markov by leaning into the tape!

Pogo, there are many, many things that you can do during your vaulter BEFORE you pushoff that can more than make up for this 3". Things that will add over a foot to your vault! I'll teach you some of them!

Kirk

I was using easy available data - something anyone can use and that don't require expensive and complicate equipment. Something which will tell you about efficiency without measuring pole friction, horizontal and vertical speed, angles, forces, energy losses, differential calculus, Fourier transformations, etc.

[dj]

good morning

thanks Barto... you just answer a 100 questions from all the threads i have thrown tid bids at...

one of Bubka's early jumps (5m grip) that i did the timing on took 1.47 seconds... T-Mack's 5.90 / 5 meter grip that i have often brought up on here took 1.44/1.43 seconds... BUT the maximum bend was slightly more than the Bubka jump.. which i'm very ok with..

the speed and "radius" of the swing indicates "application of force"... the “big bend” but very positive result means he was on a pole flex that did not “hold him back” at the plant (to stiff of a “spring”) or take away from the energy “in” at the takeoff.

Since I’m on the side of catapult-no catapult that “thinks’ we swing off the top of the pole, the speed of that swing and the “continuousness’” of that swing is imperative.

Back to the “big bend”.. Bubka himself was one of the first vaulters to bend the poles 30%. That might be interpreted as .. big bend.. bigger catapult… but when you factor in the speed of the swing and the continuousness of the swing you now cannot rule out that you can “swing” from the top of the pole as opposed to being “catapulted.”

I got the data and both these jumps from Peter McGinnis’ filming.

The other element that needs to be factored in is the “impulse” at the take off. Of course a “free takeoff” (an “up” impulse just before the pole contacts the back of the box) is the goal.. but there must be an “up” impulse so that the continuity (continuous chain) is not broken. An” up” impulse (yes I’ll let some of you call it a jump ; ) ….. goes a long way to “lightening” the load so there can be a continuous chain.

When you run into the plant without an “up” impulse you put more force down toward the ground.. which stresses the pole more and works against moving the pole to vertical. This has to slow the swing..

So an “up” impulse, totally free, slightly free, not quite free is better than no impulse at all and running yourself into the box.

Big bend…. no impulse, slow swing, negative result……..

Big bend…….. good impulse, fast swing, great result.

Which brings me back to my originals point; time and distance, longer distance in less time, indicates application of force and a more continuous chain.

Which brings us back to the Petrov model. Which I think is based off of physics.

You have to put the numbers with the pictures for the “more” complete story.

dj

[KirkB]

DJ,

I like what I'm hearing, and I think it ties into my revelation regarding the time and distance whilst you're "in the air" (before pushoff).

I'd appreciate it if you could address my specific ideas about time and distance re the importance of minimizing them to minimize gravitational pull. If you think I'm all wet on this, please don't be afraid to tell me. I just need to know. It sounds very similar to what you just said above.

The only area where I think I have a slightly different interpretation of the physics involved is in what you call "the swing". i.e. swinging all the way to the pushoff.

I call it "the swing and then the extension" because I believe that they're 2 distinct vault parts, albeit one melding into the next.

Some people believe that an "extension" is a somewhat passive vault part where you basically let the pole catapult you skywards. I don't see it that way at all (if done properly). In my personal experience, it's very much as active of a vault part as the swing is. That is, the start of the extension is from not a tucked, but definitely a piked position. As you pass the chord, this piking is a natural consequence of carrying the momentum from your whip thru (from a reverse C to a forwards C). From there, you ACTIVELY extend in unison with the propulsion of the pole. The timing of this is critical to be one with the pole. And an early inversion is better than a late inversion. Far better. Without the early inversion, you can't have a TREMENDOUSLY active extension. The type of extension I'm speaking of is identical to the first part of a clean and jerk - the clean part. Both in the amount of force exerted, and in the path that your arms and torso follow, it's identical. If you can clean 300 pounds, then I'm speaking of exerting that same force (or as close to it as you possibly can) on the pole. Surely you can't call that passive!

Anyway, call it a slightly different style than your ideal "full swing" vault, and to each his own, but even the way I see Bubka vaulted, I see that type of an extension in his vault. Everyone sees what they want to see, and they also see what they've personally experienced, so that's where I'm coming from on this.

I don't think we're too far apart on this topic.

My thoughts on this haven't changed since back in the day, with 2 exceptions: (1) I realized that once I got to the point of a fully "continuous chain" technique (in 1971), I went past that in 1972 and started over-emphasizing the extremities of my technique - to the point of crushing the pole too much, causing extra distance for my CoM to travel, and consequently extra time to travel this extra distance; and (2) my recent realization of the importance of time and distance whilst in the air. I just never thought of it that way, although there's no doubt that in my best jumps in 1971, I traveled a shorter path, and took less time to do so. If you refer to the swing and extension sections of my Bryde Bend thread, you will see that I described it last summer just as I'm describing it here (with the 2 noted exceptions).

What do you think?

Kirk

[dj]

good morning..

i actually feel i'm in total agreement with you...

Some people believe that an "extension" is a somewhat passive vault part where you basically let the pole catapult you skywards. I don't see it that way at all (if done properly). In my personal experience, it's very much as active of a vault part as the swing is. That is, the start of the extension is from not a tucked, but definitely a piked position. As you pass the chord, this piking is a natural consequence of carrying the momentum from your whip thru (from a reverse C to a forwards C). From there, you ACTIVELY extend in unison with the propulsion of the pole. The timing of this is critical to be one with the pole. And an early inversion is better than a late inversion. Far better. Without the early inversion, you can't have a TREMENDOUSLY active extension. The type of extension I'm speaking of is identical to the first part of a clean and jerk - the clean part. Both in the amount of force exerted, and in the path that your arms and torso follow, it's identical. If you can clean 300 pounds, then I'm speaking of exerting that same force (or as close to it as you possibly can) on the pole. Surely you can't call that passive!

also the point about gravity is dead on... not only does the swing help fight gravity, but the unbending pole has to add a little "lift" to an already moving lighter, mass.... it's very hard for me to term that lift "catapulting" because our readers seem to consider catapulting, or when we say catapulting .. it is considered a "total" throw... i think the swing, and extension, creates more height above grip than the "catapulting" effect.

the height above grip is a combination of the swing.. some "lift" by the pole to lighten the "load" or mass of the body and as you said a very active extension.

i sometimes relate it to the finish of a discus throw... if you spin correctly.. land and "block" correctly the arm becomes a 'catapult" a mere accelerated flick of the wrist is all that is needed to "throw" (catapult) the discus correctly.. if you slow the action and try and put more power into the throw you lose the throw and benefit from the spin.. and the length and speed of the radius…

I look at the finish of the vault that way… I agree there is a “pull” or active move to propel the body as high as possible above the grip.. I do/did it myself on steel and fiberglass and see it in all vaulters.. tim Mack practiced that move and called it a “superman” pop up…

but the extension should be a fast (and agressive) move.. with the body inverted and ahead (on top of the arc) of the pole.. much like the “follow through” flick of the wrist in the discus..


dj

[KirkB]

DJ, thanks for your confirmation that we're on the same page.

Your discus analogy is a good one ... I think ... my discus throwing skills are a little rusty ... to say the least! But I know what you mean ... about planting your foot to anchor the forces ... and then since you already have the discus moving so fast, a little flick is all that's needed to add yet more momentum to it as you release it from your fingers. You wouldn't think that a little flick would be all that important, but it's the easiest time to add yet MORE momentum to the discus ... while it's already moving at almost near top speed.

Same thing for the vault. Your body is the discus that you're propelling skywards. Whatever you can do to "flick" it even higher, you should. When I refer to an extremely active extension, I'm actually referring mostly to the body action of straightening up into the inverted "I" position. Perhaps the discus flick analogy is just the final pushoff with your top arm and wrist?

One other thing ...

In talking about the extension being passive or active, I would say that it can be (and should be) even more active than the swing. If all you're doing is swinging, that's more passive than extending. Perhaps it's a bit of both, but my assertion is that an active extension is better than a mere continuation of the swing. It's more ACTIVE! The difference between an active swing and an active extension might just be semantics, but I want to emphasize that if you're not STRAIGHTENING your body VIGOROUSLY, you're not optimizing the amount of energy you're putting into "the system". In my mind, a continual swing just isn't as VIGOROUS.

Kirk

[dj]

hey

i know what your saying..

it is active.. say like a "kip" and shoot!! added to the swing..

or the feeling you may get when you swing from the end of a rope over water.. where you want to get as high as possible to do a front ..one and a half dive into the water?

but in the vault you have the "lift" of the pole that is "lightening" the load so to speak... so it doesn't all have to be or seem to be muscle.. sometimes when you "feel" it too strongly it took to long and you will "fall" of the pole instead of "fly"..

of course way back in the early seventies we keep thinking you had to "rockback" and wait for the pole.. but when Earl, Dave Roberts and Tully came along we saw that the physics would dictate a "active" continuous swing action so you were not "dead weight' on the pole.

not being dead weight on the pole is one of the reason i am very emphatic about a "impulse" at the takeoff.. just as in the long jump... to do this “move” (jump/impulse) you cannot have a long last step or be "reaching" at all... you need a penultimate to do it correctly.. and you need to run correctly to have a penultimate. That science was done in Russia way back in the sixties with long jump analogy..…

and that last statement is not off topic because if you reach you have little chance of having a continuous chain and you will normally go flat off the top.

That is why it is very difficult to talk about one “phase” of the vault without bringing in points from the continuous chain… and the continuous chain starts with the run and not at takeoff.

dj

ps.. and just a note on the discus analogy.. the front foot "block" in the javelin and discus is simular if not the same "physics" as the pole tip planted into the box...