altius wrote: According to him there is no benefit from the shortening of the pole as it flexes and no 'catapulting' action from the pole. You are free to believe what you like.

Ok - so here is something that I dont get.
Why CAN'T you compare a pole vault pole to a catapult. The pole does exactly that. Think about what a catapult is and how it works. You store energy into it, and it returns the energy quickly to launch something. If the pole didnt have the ability to give you a return of the energy you put into it, you would not see the push offs that you see today.
I definitely dont agree with the concept of 'the only benefit of a flexible pole is that you can hold higher/use longer poles', because that's bull sh--. Look at the pictures and images of stiff pole vaulter - how much of a push off are they getting on the top end? Have a vaulter invert himself on a rope or verticle pole and turn and push off. Now compare that with the push offs of many elite vaulters - Bubka, Tarasov, Hartwig, Toby, whoever you want -you will see nowhere near the amount (with a stiff pole or stationary) as you do in a vault with a flexible pole. The pole's ability to transfer horizontal energy into verticle is definitely advantageous to the vaulter.
Now I understand the need to be cautious with how you explain what the pole is doing and how to exploit it, but the word catapult works just fine if you explain it correctly. All you have to do is relay that a catapult required alot of energy input in order to get the return it gave, and that you can't be passive during any phases of the vault. Piece of cake. In Beginner to Bubka, it seems to bash this idea, but ONLY in conjuction with the issue of emphasizing maximum bend of the pole and passively waiting for a return on that energy.
As I've stated many times in the past - when refering to termonology problems like this, you're getting into semantics - which isnt necessary. Neither myself nor any of my vaulters have ever emphasized bending the pole over 'moving' the pole, nor do we practice or preach any passive phases in the vault - yet we use the term 'catapult' all the time.
Also - when refering to viewing the vault as an 'infinite series of straight poles of varying lengths' (taken from BTB)- that may be true when thinking of the biomechanics involved with the athletes body and the vault - however, ask any pole manufacturer, and they will be glad to tell you that the pole is doing alot of work (due to the energy the athlete put into it of course) to bend and roll smoothing while recoiling back to the straigh position - which is an action that very much resembles a catapult. Just look at the videos I posted on the Shoe Vault - we bent the pole (stored energy), attached a shoe and released that energy - the shoe went VERY high. The energy IS THERE. To say that a human body reacts differently to that SAME energy return is just not possible - this is simple physics - its all just mass. To say that there is no additional energy that the pole is giving, or I guess better to say 'returning', at the end of the vault, is simply not true.
While the pole is on the way down in this picture (so a slight allusion of a larger pushoff is there) You still cannot tell me that Bubka or anyone else could get this kind of push off on a stiff pole.
