[quote author="Carl Valle" date="1313039747"]
[quote](3) If you increase the RFD and stiffness vertically does that do nothing to horizontal speed?
If you only increase it vertically, then no, it will do absolutely nothing…and if you think differently then you still have no grasp of basic, elementary physics. Again, vertical force does absolutely nothing in regards to horizontal motion. Vertical force simply provides a window allowing an object to travel without the negative effects of friction, put it provides no propulsive input to the horizontal motion. Please read through and workout some basic elementary equations involving trajectories. If you do not increase the horizontal force input, you don’t add to the accleration or deceleartion of the object. You need to think in terms of the “rate limiting factor”.[/quote]
Star, you are inferring that force aimed vertically will be applied vertically, instantly and entirely. Thats not how the body works though and I think this is where the hang up is between the two of you. You are looking at the body as a machine and Carl is looking at it from a coaches perspective.
Nobody is saying horizontal force isn’t necessary to accelerate further. Clearly some propulsive force is necessary. To increase horizontal speed past a certain speed, however, the force must be attempted to be applied vertically, as that is the only thing that creates a strong enough force to adequately stretch the tendons and then return that stored energy back into the track. Since your body is in forward motion as your foot is now stationary applying power to the ground, as you have pass over your foot the power is applied is an increasingly horizontal manner until toeoff.
The aim is vertical but the result gets you down the track.