Posted by: Major Dan (markj89@charter.net) on Thu Jun 7 11:47:34 2001

>>> More interesting reading at:
> >
> > http://setpro.com/NEWWEB/mmax02.htm
> >
> > This is info more specific for hip turn in pitching, but there are some similarities. In pitching there is linear to rotational conversion and rotation and motion about complex axes and a benefit to pushing the rotating body forward, etc.In both there is momentum transfer through the kinetic chain which is characterized as dynamic-torsion created by twisting and untwisting the body which transfers momentum and static-pulling the torso around adecelerating lower body after the two have begun moving together due to torsion.
> >
> > The torsion part accomplishes best momentum transfer by making the link to the torso when the hip turn velocity is maximum. Once things move together the muscles can add to torso rotational velocity by pulling. Is this how others interpret this? <<<
> >
> > Hi Tom
> >
> > I see a more direct drive from the lower body generating upper body rotation than from momentum developed from intentional separation. I am sure we all agree the hip rotation leads shoulder rotation. During the inward-turn, the counter rotation of the shoulders has the hips ahead by 20 to 30 degrees at initiation. Where we may disagree is what causes any further separation.
> >
> > Would you say that further separation (greater than the 20 to 30 degrees at launch position) is the result of sequential lower-to-upper body timing mechanics – or – is any further separation due to overcoming the added dynamic load offered by the upper body mass and accelerating the bat-head? --- Stated another way; At initiation, do you believe the firing order (or contraction) of the lower-to-upper muscles groups is “sequential” – or – do believe the lower body and torso contractions are more in “unison”?
> >
> > Tom, I hope you can make some sense from what I wrote.
> >
> > Jack Mankin
> >
> >
>
> My GUESS/PURE SPECULATION is that separation is maximum as hand path starts forward.This comes shortly after front heel plant with some additional plyometric type stretch just before contraction works its way up to turn/pull the hands forward.This untwisting transfers momentum and sums velocity as instantaneously as the muscles connecting the skeleton allow.By the time the front foot comes down,however,the brain has already selected the program it is going to execute based on training and experience and different degrees of twist/untwist and timing are possible.

Tom -
It makes sense to me that separation is at maximum when transfer to shoulder rotation starts. The goal of hip rotation leading shoulder rotation is to allow that transfer when the hips are at maximum rotational speed. Once the shoulders start to rotate, the hips will slow as energy is sucked out into shoulder rotation and the shoulders will start to catch up.
The key is to have enough separation to allow the hips to attain a high velocity. If hips and shoulders start together, you have 0 hip rotation speed and 0 shoulder rotation speed. If you wait until hips have finished turning you also have 0 hip rotation speed and 0 shoulder rotation speed. As soon as transfer starts, hips slow, by definition - otherwise there is no transfer. There must be separation in order for the hips to develop enough angular momentum to have something to transfer.
Just as Jack says that batspeed must be maxed by contact (not after), so must hip rotation speed be maxed at transfer time. This cannot be done with a unit body turn.