Posted by: tom.guerry@kp.org () on Sat Oct 4 10:03:59 2008

Jack-

as far as a useful model of the swing, this link from Zig's old company demonstrates the
kinetic link principle underlying both golf and hitting swings.

Some aspects of the swing CAN be thought of as linear but still result in segmented
stretch and fire of body links in an effective sequence. For example, while the bat is
turning about a point between the hands beginning with PreLaunchTorque, this
acceleration also involves the bat moving into a "linear" 2D plane that matches the pitch
trajectory to create an effective contact zone/intersection which is in a different enough
plane form the way the more level hips turn the body to create control of body load/coil.

This linear aspect is much more obvious in the old fashioned 2 plane golf swing where
swinging the club down by dropping the arms increases torso stretch as the pelvis turns
the body open in a much more horizontal plane.

Phil Cheetham is the expert who is working mostly in golf now and has a number of
articles on how his "6 degrees of freedom" 3D motionanalysis can be used.

See especially a comparison of expert to nonexpert sequencing/speed gains here:

http://www.advancedmotionmeasurement.com/Articles/KinematicSequence-
TransitionandDownswing.pdf

Note the "rushing" flaw in my opinion is when arm segment speed peaks before torso
rotation speed peaks.

casting is when the club speed increases too much too soon and the speed gains through
the segments becomes inefficient so that clubhead DEcelerates before contact.

I think these are good objective descriptions of what happens/ is being described by the
feel of "rushing" and "casting".

Cheetham has also done a lot of work on hitting as reported by Zig.

In my opinion, the MLB hitting swing is similar to the golf swing in using the kinetic link,
but is optimized for hitting which requires a far greater challenge of adjusting the swing
because of reaction time limits, but a lesser challenge in not having to worry about
coordinating clubface closure AND by having a larger target (just keep ball fair, not hit
green)

Not having to worry about clubface closure allows you to use/adjust swing plane to pitch
much more than you can line the swing plane up with the target line in golf and this also
frees up the hands to be in charge of getting the bat on plane in hitting.

In golf, the hand action must be in large part reserved for clubface control through the
impact zone. Arm action and body synch are used to get and swing the club on plane.

This allows the mlb hitting swing to have the active handle torque you describe.

The only major difference we have in my opinion is the shoulder action and exact
handpath shape details.

I think of the shoulders as needing to be primarily tilting to support the forearms and
hands in torquing the bat and setting a swing plane that the body turn conforms
to/supports. So in my opinion, THT at Launch requires the primary scap/shoulder action
to be tilt which puts the hands in charge of swing plane orientation and timing while
additional load/coil of the torso is created.

primarily turning (instead of tilt being primary) the shoulders rushes the torso so that it
can get out of sequence and be unable to stretch and fire/unable to "peak" before the arm
segment speed peaks.

In hitting, in your terms, to get the right sequence, you "retain the power V" in the back
arm while the torso stretches more and reverses, then the torso rotation speed peaks as
the arm segment next accelerates to max as the back forearm starts to lower.

So I think you are getting efficient segmentation and sequencing by emphasis on torque
and keeping hands near the back shoulder, BUT, I still think that the shoulder TURN
emphasis is too easy to overdo and omits the tilt aspect necessary for the hands to set a
well matched plane with optimum coil/load of the torso/thorax.

Your description of "casting" as not being all bad is also a VERY important/good point. You
must accelerate the bat early by handle torque and the arms can "cast" some early as for
long swing radius (which is before the torso finishes coiling/before more pronounced tht
at launch as you continue to then retain the "power V" even in this case).

the downside of casting is only if it accelerates the bat in a way that degrades rather than
enhances coil/load. Getting the direction of this aceleration "right" to "resist" instead of
"rush" may benefit from "LINEAR" cues.

The bathead does need to accelerate early, BUT it needs to accelerate in a plane that
resists turning open as the hips turn so that load/coil is not "rushed'.

Many good Cheetham articles with detailed motionanalysis descriptions are available in
the research section of the titleist peformance institute (in San Diego/Oceanside). The
website requires registration, but is free.

see

http://www.mytpi.com/