Posted by: SJD (nospam@nospam.org) on Wed Nov 30 14:01:55 2005

I think Jim's turning car analogy isn't quite correct. A car's linear motion becomes curvilinear after the turning of the steering wheel, and the resultant frictional force placed on the tires causes the vehicle to move around a radius.

There is nothing similar in the changing of linear to rotational momentum with a bat swing, however. Jack is correct: the force required to rotate is provided by the hips/legs.

As proof, Jim, try your own experiment: move from hitting stance in a linear fashion & translate into a rotation (without stopping) and see if you can't feel your hips/rear end muscles facilitating the turn. It can't be done without torque from the hips/butt.

Better yet, have your wife or girl friend put their loving hands on your rear & hips to confirm the muscle action. They should feel the muscles flex, illustrating the point.

But success or failure, this experiment just might lead into unrelated non-hitting activity that's loads more fun than hitting, be it linear OR rotational... ;D

sjd(at)cogeco(d0t)ca

> >>> The clip (http://www.batspeed.com/media/WhipHigh.wmv) is an excellent demonstration of your point regarding the blocking of linear motion. I agree that a linear hand path cannot create a “whip” effect and the same would be true of the hips IF linear hip slide were “blocked”.
>
> However, I do not believe that hip slide is blocked or stopped by the firm front side in the way your clip illustrates. One role of the front leg is to redirect the front hip as it approaches its limit and help change linear motion into rotational motion by turning the front hip. In most cases, my pro clips reveal that the hips show detectable hip rotation 1-3 frames BEFORE the forward limit of hip slide is reached. The fact that hip rotation usually begins BEFORE linear hip motion ends is compelling evidence that the front leg redirects the motion of the front hip. One would think that if this relationship did not exist we would never see hip rotation beginning prior to the end of hip slide. In no cases are there stopping or blocking of linear motion and then starting of hip rotation. Linear leads fluidly into rotation.
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> Think of it as a car driving in a straight line and then turning into a curve. The car doesn’t have to stop in order to turn. Neither does the front hip.
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> The “whip effect” analogy does not relate to the hips because appendages are not involved as they are with the upper torso and arms.
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> I do not mean to imply that linear hip slide is the main source of energy created by the hips during rotation. It is not. The interaction of both legs and the torso muscles creates vastly more energy. It does, however, make sense that hip rotation building off of body parts that are already in motion will be stronger than hip rotation that must build off of static body parts. <<<
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> Hi Jim
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> It would be a pretty boring discussion board if we all agreed on all points. You seem to think the front leg redirects hip slide into rotation. I say that torque applied to the hips from the extension of the lead-leg is the key to good rotation. I do not see the front hip redirecting as it slides forward - I see it being driven rearward.
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> Jack Mankin