Pvstudent, There are many key factors that you
fail to consider and your obvious strategy of attempting to redefine and confuse a commonly used term by others and myself of "Pull" is entirely misleading and completely invalidates your argument.
Pv student wrote:
1. Once the toes of the vaulter’s take-off foot have broken ground contact the only bio mechanical action the vaulter can perform is the exertion of muscle torques resulting in pull forces exerted on the pole.
Wrong and very poor coaching at this stage on your part!
Just as you can tense a muscle, you also have the ability to RELAX a muscle.
As a supposed "bio-mechanical expert" you have failed to identify a VERY important principle of muscle physics called Stretch Reflex. Stretch reflex simply states that a pre-stretched muscle has a re markedly improved ability to contract at faster rate. A phrase that many "knowledgeable" coaches use at this stage of the Vault is called"Going Elastic"
. By failing to identify and promote this very important action at this stage of the vault you have already predisposed your vaulter to a slow swing!
Note to exert a torque a muscle physiologically is only able to exert pull forces since all a muscle can do, upon receipt of neural stimulation,
Note to relax a muscle group (In this case all the muscles that surround the shoulder joint) as vaulter should in order to "go elastic"they only need to make a concious effort to not send neural stimulation to them (relax them).
is attempt to shorten due to the formation of cross bridges between the actin and myocin filaments of the muscle and the operation of the “all or none law”. Muscles cannot push anything they can only pull!
Ya so what ? Muscles shorten when you "pull" and they shorten when you "push" and any idiot knows the difference between those commonly used terms here on PVP.
2. Once the vaulter’s takeoff foot has broken contact with the ground there is linear translation of the vaulter upwards and forwards towards the plane of the cross bar whilst at the same time there is rotation of the vaulter’s centre of mass about both the left and right wrists as well as the vaulter’s shoulder joints.
In other words the vaulter is swinging on the pole ie undergoing pendular (rotary) motion about the grip locations on the pole! For this to occur the vaulter must be pulling on the pole and the pole pulling on the vaulter!
3. For pendular motion to occur there MUST BE a centripetally directed inward pull on the vaulter acting towards the axes provided primarily at the wrists.
Newtonian physics applies in that so long as some of the vaulter’s weight force is acting on the pole, and the vaulter is showing pendular swing on the pole, a centripetal force is being exerted. If a centripetal force is acting on the vaulter the vaulter must rotate about the pivot axes (wrists) and therefore must be pulling against the pole for it to be pulling against him/her.
4. Since the total system (vaulter plus pole) is also rotating about the pole tip axis at the same time, points (1-3) also apply. Hence both the lower arm and the top arm of the vaulter will also be exerting pulling forces and creating torques about the vaulter’s body segments and on the pole tip pivot point in the planting box.
Ya so what? A centripetally directed force has nothing to do with the the conscious action of pulling through both shoulders that I am referring to.
Your post clearly demonstrate that you do not understand;
1. The importance of going elastic to achieve stretch reflex
2. The importance of re-extending (pushing) the plant while going elastic and why?
3. Pulling through Both shoulders (Not just the bottom as you stated). In fact you still have not identified the when? Just as I have told the reader you would not!
4. How the timing of the pull should coincide with proper pole rotation position and hand placement.
5. The interconnection of all of these actions and how and why they are all symbiotic to each other.
All 5 of these points are hugely critical and you have failed to address every one of them. This just proves that you are way in over your head and do not have the ability to debate me on this topic or even address the original challenge I poised to you, which was to simply define the correct timing of the conscious action of the pull and back it with rational.
I have with 7 reasons. Your turn......................
So you have still failed to address the challenge I poised to you of clarifying the timing