Posted by: tom.guerry (tom.guerry@kp.org) on Sun Mar 16 09:38:12 2003

A batter with good transfer mechanics will deplete all energy for
generating bat speed prior to contact. Question: if a batter has
strong wrists should she delay THT and BHT until the last
possible moment, which would result in a large amount of
tension to get the energy depleted. or would it be better to start
applying the torque at launch, which may result in the energy
being depleted with less tension at contact. another way to
phrase the question might be: should torque be initiated or
timed to culminate at contact with massive tension to
completion,or a more relaxed slower torque?
> i think i know the answer but would like to hear some first hand
experience... thanks very much!!!
> love this board...Rich

I vote for gradual.

My interpretation of Jack's swing model is that it consists of 3
arcs.1-hip rotation,2-torso rotation driving handpath,hands fixed
to torso,3-bathead arc rotating theoretically around point
between hands.Of course this is a great simplification,but
seems reasonable.Also.as the bat turn picks up speed(goal is
max acceleration)the hands role becomes more and more
reactive to bat motion.

For a quick,short rotational swing,transfer of force and
momentum through the body appear to require the transfer
mechanics described by Jack which have the more steady and
early turning forward of the 3rd arc.

My idiiosyncratic thinking is:The first part of the swing involves
"cocking" or loading the hips as the stride foot lifts.Then the
torso loads via what Nyman has described as scapula
loading(pinch back shoulder blade,back elbow goes up) which
creates some counter rotation of the torso as the stride foot
goes out.Then upper/lower body separation is created as the
hips begin to uncock,usually synchronized with the front thigh
starting to turn over(external rotation front leg associated with
opening of hip)and the back elbow beginning to drop as the
back arm externally rotates.

The hip uncocking/opening also immediately involves the back
leg internally rotating.The back leg and front arm prefer to work
synchronously which means that the lead arm internally
rotates(works up tightening,not loosening connection) as the
back leg does the same.These coordinated movements are the
start of the 1st(hip) and 3rd(bat)arcs.These 2 out of phase arcs
continue loading/separating the body.The hips continue to open
and the torso/hands continue to "stay back" as the internal
rotation of the lead arm and the external rotation of the back
arm("form the box") turn the bat back toward the catcher and
connect the hands tightly to the torso.This creates a stable/
efficient configuration to then allow transfer of momentum
through the body,transforming this energy into quick acceleration
of the bat arc.

Since before "hip cock" the center of gravity of the body has been
put in motion and kept in motion,controlled mainly by flexing
action of the back leg(this also creates a nice shape when its
time for the back leg to internally rotate to support hip uncocking/
rotation).As Nyman explains,the hips must be accelerated to
maximum turning velocity as they hook up and start to turn the
torso to get the most efficient transfer of momentum.How well
the hips decelerate is then a measure of how efficient
momentum transfer was.The front foot resistance to center of
gravity motion permits the hip turn to accelerate to the
maximum(if weight has not gotten too far forward) and then
"launch" the 2nd arc(torso).

This is a different sequence/transfer mechanic from the long
rotational swing of golf(still ball) for example.In the case of golf,a
common teaching(and design principle for some testing
machines) is to keep the wrists cocked as long as possible
based on the physical principle of the "double
pendulum".However,in addition to the infinite reaction time of
golf,the swing is much longer(bigger backswing and contact
after wrist roll) so you have a different solution to the task.