Posted by: Jack Mankin (MrBatspeed@aol.com) on Thu Dec 15 12:49:07 2005

>>> jack,look how far the back foot moves and how much their head moves too.What causes the back foot to move up so much,is that a signal that at some point you are no longer spinning on that axis?Or does that motion happen after all the rotation is completed? hers the clip

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Hi Mark

In the clip you provided, you ask, “What causes the back foot to move up so much” – I think we can agree that the rotation of the back-hip around toward the pitcher is mainly responsible for dragging the back-foot forward during the swing. Since the back-foot is being drug forward, it is also apparent that the drive (or extension) of the back-leg is not powering hip rotation.

Some batting authorities have concluded that momentum developed during the stride is what causes the back-hip to rotate. However, the transfer of momentum must follow physical law rather than the wishes of a batting theory. As the clips you provide show, at foot plant, the back-hip is in-line with the lead-hip. This means that when the lead-leg blocks hip-slide, there is no rotation induced because there is just as much tendency for linear momentum to rotate the back-hip clock-wise as counter-clock-wise at foot-plant.

Just because a right-handed batter wishes to rotate his hips counter-clock-wise will not alter the laws governing momentum. The tendency for the hips to rotate one way or the other are balanced when in-line and momentum is directed straight away – Like an arrow striking a tree, it does not snap off because its linear momentum is directed in-line down its shaft and into the tree.

I have stated before that muscle contractions in the lower-back and hips along with the torque supplied from the extension of the lead-leg is mainly what drives hip rotation.

Jack Mankin