Discussion with Tom cont
However, once the bat has been sweep back into the swing plane, there should be no further internal or external rotation of the lead-arm The lead-wrist remains palm-down and the elbow stays pointing into the swing plane.
I agree with this, BUT I do not think the bat has to enter the roughly 2D swing plane it fires to contact in until somewhat less than 4 frames before contact in high level swings which is somewhat after shoulders have tilted/been turned, .
It is the rotation of the lead-shoulder that pulls the bottom hand around with the arm suppling the linkage. Therefore, I would also have problem with claims that internal or external rotation of the arms rather than shoulder rotation that is the major power source
of the swing.
This linkage is driven by the unwinding of the torso with chp for last 3.5 frames or so to contact, but the earlier arm/forearm action assists in coiling the torso/separating the upper and lower halves as soon as the back elbow plateaus and starts down/as soon as
the front knee starts to turn the front foot open which is well before toe touch.
Other than a frame difference in our analysis, I would say we agree after the terms we use are understood. Example; what you refer to as “the unwinding of the torso,” I call “shoulder rotation.” – Tom, it is the end of the month. I will open the new month with our discussion.
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