willrieffer wrote: So you might get a case where the methodology worked, but for reasons other than the ones stated. Or that the stresses on the particulars might be out of sync with the physics explanation.
KirkB wrote:When a vaulter executes a vault, he usually does so with some cognizant INTENT to use the Laws of Physics to his advantage. But sometimes, HAPPENSTANCE happens, and sometimes INTUITION happens. In either case, the vaulter (and/or his coach) may not fully understand why something that they just did worked well, but it still follows the Laws of Physics EXACTLY. This has personally happened to me on a few occasions.
Happenstance is basically a coincidence that (in the context of this discussion) just happens to be a combination of GOOD things that happened during a vault.
And intuition is basically a good combination of things that happened not because the vaulter intentionally did them on THAT particular vault, but because his training regimen caused his muscle memory to react in a rather automatic way. A couple good examples of this are the way Kjell Isaakson was so vague about how he swung ("I just jumped"), and the way Bubka described the details of how he swung ("Arrrrgh"). This is the reason that I encourage highbar work so much.
I don't mean to be defending Will too much here, as I probably disagree with more than half his "scientific" assertions. However, his alternate, minority view has opened my eyes wider than they were open before.
I can use, for example, the idea that the method is concerned about losing energy in the box. According to the laws of physics, of conservation of energy, because during the vault the box doesn't move, there can be no great loss of energy. IF the box cannot be a major source of energy loss to be concerned about, what is the concern with this idea about? IS is simply something that is a useless boondoggle of their method? Or is it something else? I think it is something else...
I will say I do have to guess here a bit on this. But I think its a good guess.
In building a worry about a loss of energy in the box it creates in the mind of the vaulter an idea and approach to elevate the take off. That if they come in low and initiate a low take off trajectory "into the box", they will "lose energy" into the box. The idea that the vaulter needs to elevate into the pole to induce pole rotation about the tip is certainly worthwhile. It leads to a better vault. That it needs to be done otherwise compared to other vaulters a lot of energy will be "lost in the box" in a magnitude negatively impacting the vault is just flat out wrong.
So again, the whole of the methodology in intent causes the vaulter to elevate into pole rotation. But the physics explanation points to an idea that just cannot be. The box doesn't move during the vault in any appreciable way. It's not a real source of energy loss. It acts the same for all vaulters. There is a little bit of energy lost there due to pole tip friction, but it is going to be very close to being the same for all vaulters, and of many magnitudes less than some other considerations. And so from a purely physics standpoint "box energy loss" is something not to be worried about at all. But from a vaulter intent standpoint? Apparently it was a very useful psychological tool for coaches in the PB model and so matters a lot. I have been working here to try and pull these things apart. The useful "myths" that impart useful intent into the mind of the vaulter in their approach, from a real physics based explanation of events.
The method is littered with stuff like this. In some sense the free take off crumbles when normal take off variance is accounted for (Bubka's own take off variance admissions coupled with Bubka's monster '93 worlds attempts coming from pole bend take offs), but for any coach there must be a goal. An idealized take off point and method. That Petrov stressed the motion of the hips is where I fall into agreement with the model and where I put the stress. It is the most important point. To them to keep them back in time, or for me to push them back in time, is the most important aspect of the vault, and I have attempted to use physics to explain why. It makes better use of the gravity vector on the pole in time. It is here where I stress it over take off methodology. And it isn't that the "free" PB model take off methodology is wrong. But it is as I say, "posture over placement". It is better to be under and be able to keep the hips back ( as with Dossevi) than it is to be on the ideal take off mark but then allow the hips to be thrown forward under pole brake( free hips model which was eclipsed by the PB model). Lavillenie, I believe, executes this type of vault and shows us its value in efficiency. He shows that his activities in keeping his COM as far back and down by his use of the front arm, the lead leg drop, and trail leg posterior motion, and then tuck to get out, coupled with his use of the "free" take off, which has generated the most efficient vault form in history. We know this because the facts of his shorter stature and rather typical footspeed for a WC vaulter make it more challenging for him to enact the sorts of all time WC jumps he has made. He makes up for it in his swing efficiency and post take off pole relations.