PV Student, I love how you chime in with thoughtful posts when the bottom arm discussion turns ugly, as it usually does on PVP.
Thank you for pointing out that everything depends on your takeoff point. I have rebuilt my technique over the last two years and can say from experience that the vault feels very different when you take off "under" vs. "on" vs. "out". I prefer "on". When you are way under you would not be able to press up through the takeoff, you would be ripped off the ground...however your bottom arm would feel a lot of resistance and push hard to keep you from slamming into the pole. When you are "on" or "out", it is especially important to extend up and through the takeoff, but there won't be much, if any, resistance.
PV Daddy,
Studying film of Bubka and other elite vaulters is very helpful, but sometimes what you see isn't necessarily what they are trying to do. Looks can be deceiving, and knowing a vaulter's intent is just as important as studying film. Most of what you are saying is correct, but there are a few things that I respectfully disagree with.
I think it is a mistake to say that you "pull with the top arm, followed by the bottom arm". Pretty much all the accepted pole vault "models" agree that the top arm should stay long and extended until the end of the swing and even beyond. Suggesting that vaulters pull with the top arm at all is a mistake, in my experience, as it simultaneously kills pole speed and shortens the swing radius. There is a strong "re-engagement of the shoulders" that starts the swing together with the whip of the trail leg, but I wouldn't call it a "pull." Most young vaulters pull with both arms as an instinct ("hug mommy", as David Butler calls it), and as a coach you should encourage them to avoid this. Pulling with the bottom arm is certainly a reality, although many disagree as to when and how this pull should be done. I prefer to teach my vaulters to swing on a stiff pole, rings, highbar, and rope; and their body will figure out the complex motion of the arms and shoulders without having to explain it in words.
The bent bottom arm should not be something that is attempted at takeoff; rather it is the result of the body's mass and velocity being transferred to the pole from the bottom arm being extended upward at takeoff. Some vaulters achieve this position by not fully extending upward at takeoff (my friend Dan U. calls this "preloading the bottom arm"), and I believe this is a mistake. Some would disagree, and you can certainly vault high this way, but it is not ideal in my opinion as it costs you grip height and pole speed if you don't truly "finish the takeoff". Either way you achieve the bent bottom arm position, it is very important to push or press it back out as your swing rips past the chord of the pole, as this lengthens the swing and rolls the pole over nicely. Again, some might disagree, but I believe this is what Hooker is talking about when he says "I try to hit the bottom arm hard as I swing to inversion".
I think it will be useful for you to listen to Petrov's speech, if you haven't already, from Reno a few years back. It is long and difficult to understand at times, but at 52:00 he nicely summarizes what Bubka, Isinbayeva, and Petrov's other vaulters are trying to achieve with the bottom arm. This speech happens to agree with what Bubka stated about pressing up at takeoff and/or "growing" through the plant with both arms.
However, you will also hear that when the technique discussion turns to Isi's bottom arm, Petrov states that the bent arm at the plant is somewhat undesirable, but is a result of a lower grip (than Bubka's 5.10 grip).
http://video.google.com/videoplay?docid ... 8931901117Cheers,
Tom