Posted by: marlin () on Thu Oct 21 01:27:43 2004

Hi, Jack

>As these great hitters initiate their swings, every one of them (type A or B) use their legs, hips, back and torso muscles to initiate shoulder rotation around a stationary axis. This means that as their lead-shoulder rotates and un-shrugs around toward the 105-degree position.


I do not deny these sentences and it is clear that bottom hand moves with the bat. But I want to say that the batter does not apply force that accelerate the bat with bottom hand.

http://www.geocities.jp/tokyomarlin/aaron.jpg

Though shoulder flexion and elbow extension occur in this picture, Aaron is not pushing the bat. His wrist of top hand is flexed. (His mechanics is bottom hand flail. )

If you watch next clip, you might think i am pulling, but it's not true.
http://www.geocities.jp/tokyomarlin/type2aa.wmv


In the pushlike movement(of top hand) of typeB, shoulder flexion and elbow extension occur simultaneously. The elbow and the hand move forward at the same time.
In the throwlike movement of typeA, shoulder adduction and elbow extension occur sequentially. After the elbow moves downward, the hand moves downward.

In these clips, Bonds'motion is throwlike and Guerrero's motion is pushlike.
http://www.youthbaseballcoaching.com/swings.html

These are concepts of biomechanics. Please, read, for example, this book. You will also understand 'flail(whiplike action)' which is called throwlike movements of an open kinetic link system.

‚jreighbaum E and ‚aarthels KM(1996) : Biomechanics A Qualitative Approach for Studying Human Movement. 4 th ed., Allyn and Bacon

Thank you