Posted by: Major Dan (markj89@charter.net) on Thu Jan 3 08:16:50 2002

>>> I am an engineer. I have been reading your site, and you make a number of salient points re: efficient power generation. I have a few questions/points, however:
> >
> > 1. You indicate in Bat Speed Research (Wrist Action or Torque):
> >
> > "The large muscles in his legs and back have rotated his hips and shoulders to a point where the belly button and chest are now facing the pitcher. His lead shoulder is now starting to rotate back in the direction of the catcher. This means that the lead arm, and thus the bottom hand, are now being pulling back toward the catcher as the bat approaches contact. --- At the same time the rear shoulder (and top hand) are rotating around toward the pitcher."
> >
> > This, while possible, does not lead to maximum torque at contact. If the batter ends his rotation facing the pitcher, and contact is at this point with the bat perpendicular to ball trajectory, then the lead shoulder is no longer being powered “back toward the catcher”, but is merely following through with residual waist action. Further, if the batter stops his rotation facing the pitcher, he must actually have decelerated just prior to stopping rotation – again reducing bat speed. Perhaps you can explain this paradox. <<<
> >
> > Hi Mike
> >
> > Welcome to the site. -- Sorry Mike but I see no paradox. What I described is exhibited in the swing of the most well hit balls I have charted. The key factor I found was that the bat was brought to contact as the lead shoulder finished rotation (or it's final pull back toward the catcher). --- For pitches from the middle-in, the belly button would be facing in the direction of the pitcher.
> >
> > You are correct. By or just after contact the lead shoulder is no longer "being powered “back toward the catcher”." All rotational (and torque) forces has been expended. The muscles in the legs, torso and limbs are now in the coast-out mode. --- Please explain the paradox you see.
> >
> > Jack Mankin
> >
> The paradox is that in your documentation you relate batspeed to a strict function of dual shoulder torque about a central axis. If you have modeled the arms and bat as rigid in accepting torque from the shoulders, it follows that the instantaneous velocity of the bat must be strongly correlated with the instantaneous velocity of the shoulders. If, in fact, the shoulders are at zero velocity on contact with the ball, it follows that the shoulders must have decellerated themselves, and the bat to some extent, prior to contact with the ball. Thus, assuming legs are critical to delivering torque to the waist and shoulders, batspeed cannot be maximal if shoulders are at zero velocity on contact with the ball.
>
> Do you see the paradox? On the one hand, you claim shoulder torque is essential to deliver maximal batspeed, but you only consider positive shoulder acceleration. You never consider shoulder decelleration prior to contact as being detrimental to batspeed.
>
> How can the shoulders speed up the bat when they rotate faster, but not slow down the bat when they rotate slower just prior to contact with the ball?
>
> Thanks,
> Mike

Mike -
I am not answering for Jack and hope he responds to your question as well.
I just want to take this opportunity to share my thoughts.
The arms/hands/bat is not a rigid unit, nor is it inextricably linked to shoulder turn.
Energy is transferred up the kinetic chain into shoulder rotation. If the arms are properly 'connected' to the shoulder turn, the angular velocity of the shoulders is imparted to the hands/arms/bat. However, as the shoulders decelerate, the energy is transferred to the hands/arms/bat which is thrown out of the shoulder rotation arc, momentarily picking up speed, not slowing down. Only if the hands/arms are kept rigid with an iron grip would the bat slow down.
As the bat tries to exit the shoulder rotation circle, the hands torque the handle, bottom hand pulling back, accelerating the bat head.
Hope this helps. Hope Jack concurs.
It's nice to have BatSpeed back on-line again!