Posted by: tom.guerry (tom.guerry@kp.org) on Mon Oct 8 22:57:13 2007

OK -

I think of tht and chp as working at both mechanical and biomechanical levels. The
mechanical can be demonstrated by computer and steering wheel knob simulations,etc.

The biomechanical has to work to harness these mechanics so the swing can be powered
primarily by momentum develoment and transfer which involves alignment of body levers/
bones and elastic and muscular soft tissue properties across joints.

At a biomechanical level, for the body to power quick acceleration well back in the swing
plane/behind the hitter the shoulders and hands have to turn back and stay back while the
hips open to stretch the torso between the hips and shoulders. Then the bathead must be
accelerated quickly to contact with good timing and direction after as long read time as
possible.


For quick acceleration, the rate of stretch/coil between hips and shoulders must end with
a quick stretch or "cusp" to be able to reverse quickly to transfer momentum as efficently/
instantaneously as possible. This rate of coil/cusp is measured in golf and hitting by Zig
as "x-factor STRETCH" (not just xfactor which is amount of stretch, but xfactor "stretch"
which means that the coil ends with a last quick stretch that can optimize momentum
transfer).

A sharp well directed coil and reversal produces the efficient speed gains of each arc (hips
then shouders then hands then bathead as Zig's data shows) via momentum transfer
which produces the summation of velocity seen in the kinetic link. The body can not make
this work by muscular force development only or with poorly lined up joint action.This
cusp is capable of harnessing soft tissue elastic and muscle reflex action to transfer
momentum if the body levers are lined up well.The high level/mlb sequence (described
somewhat more sequentially than the actual more overlapping reality) requires:

1-Inward turn and hip cock:

The turning back is via an early inward turn of the whole body without much if any coil/
separation yet between hips and shoulders. Weight shifts to back foot and offcenter
balance is provided by hip cock as waist is pinched.

Hands may come in toward center for easy turning back (seen sometimes as "hitch") the
back arm internal rotation "cues" body to cok hips,slow the backward turn and minimizes
any tendency for xfactor to start. lead arm comes down/in toward body.

Internal rotation of legs and back arm synch.

2-Hand cock:

Internally rotated back arm lifts, shoulders tilt front shoulder down/back shoulder up
more, hips finish back ward turn, shoulders continue back beginning first real bit of
separation/x-factor, stride foot/weight goes down (start some "sit") and forward/"positive
move". Lead arm stretches. synched aBduction (lift) of front leg and back arm.

Bat finishes "tipping/cocking".

3-Rubberband winding:

Significant coil/creation of x-factor stretch starts "cued" by synched external rotation of
back arm and front leg.

This is immediately followed by lead arm internal rotation ( and also slight elevation of
lead arm) in shoulder socket and hips starting to turn open following lead leg turning
open (external rotation of lead leg started when back arm slotting started with the
synched external rotation).

Handle is torqued, bat starts accelerating back toward catcher. Hands stay with back
shoulder. Shoulders stay turned back and tilted, front lower than back. Weight continues
to shift forward, but center of mass of body remains behind place where front/stride foot
will subsequently form base (future "center of pressure" of front foot). Font toe is
touching, pitch location has been recognzed, "GO" decision has been made (but can still
be aborted for a bit).

4-Drop and tilt:

As result of "GO" decision based on location recognition, the handle torque maxes out as
the shoulders UNTILT and forearms twist. Lead arm remains internally rotating on lead
arm socket.Ther is someup/down arm motion. Front shoulder MUST NOT ACTIVELY TURN
as part of this tilting. Front shoulder elevates some, lead arm elevates some.

The result is to finish coiling the torso with a quick stretch while acclerating the bathead.

Bathead has not "launched" in sense of launch requiring the bathead to be outside the arc
of the handpath/CHP to receive momentum.

CHP does not exist until torso coil/x-factor reverses. Torso coil does not reverse until just
before "lag" position.

Shoulders start to BE turned as uncoiling works up from hips to shoulders while bathead is
still accelerating from handle torque assisted by forearm twist and shoulder tilt and even
some up/down arm action.

Even at this point, hips are turning open faster than shoulders and then connection/
reversal of coil is cued/triggered by torquing the bathead out of the arc of ther handpath.

5-Swing


When coil reverses, hips decelerate, shoulder turn accelerates.

Hanpath may be locked with front shoulder (turning on inside pitch/low load) or there may
be a multiple pendulum situation (outside location/high load) in which shoulders turn to
contact while forearm extension moves hand path,then wrists unhinge. (instead of lead
arm/bat forming double pendulum, lead arm, forearm and bat form triple pendulum,
ineither case as you have observed, the front shoulder continues to be turned until contat
if load was adequate and timing is good).

Swing quickness will degrade if you try to actively turn the shoulders or turn everything
together. This will lose the sharpness of the coiling cusp as well as control of timing nd
direction of swing. Moreover, this will prevent keeping the shoulders back and force later
batspeed which means slower acceleration and contact further out front and shorter read
time.

Instead, the swing "feel" is "hips and hands". You have to torque the handle via the hands
and fire the hips at the same time and focus on turning both the handle and the hips all
the way to contact even though what happens as the swing progresses is that the proximal
links segmentally decelerate.

The KEY upper body controller of the coil sequence is the internal rotation of the lead arm
which keeps the rubberband winding/coiling and permits more quickcoil when the drop
and tilt is superimposed.

Turning the shoulders at drop and tilt/"GO" means they interrupt a good coil and then
GET TURNED less effectively as the swing progresses.

The focus needs to be on turnng the hips and handle, mainly the handle, not the
shoulders.

The hips and body turn in the right sequence IN RESPONSE to the hand action - where the
hands load (line of weight shift is adusted by where hands load) and when and how the
hands torque the handle (which determines when the front leg opens and when the weight
shifts).

This is why many top mlb prctitioners descibe the feel as hands and hips creating a firm
front side so you don't fly open.

Trying to turn the shoulders will mess this sequence/feel/control up.