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Re: Re: Re: Re: Re: Re: Re: Re: Fastpitch hitting -- Linear vs Rotational

Posted by: Jack Mankin (MrBatspeed@aol.com) on Sun Oct 28 14:04:03 2007


"As force is applied to the back foot, it creates a linear shift of weight, at the same time, their is a release of rotational energy around (rotating) from the front foot up to the hip of the front leg (the heal of which has dropped during the linear/rotational shift, to provide a solid front side to hit against). At this point there is an X-factor stretch of approximately 12 degrees (x-factor stretch is an increase in the degree of separation between the hips and shoulders)."


"During this first phase of the swing the forward swing there is an expected angular speed gain (progressive speed gain) of pproximately 200 degrees per second from the hips to the upper torso, as the hips rotate and peak to a speed of 550 d/sec [during "initiation" which ends at about the "lag position"], and upper torso rotates and peaks milliseconds later at a speed of 750 d/sec. There is an additional speed gain of approximately 250 d/sec from the upper torso to the arms (which reach a speed of 1000 d/sec milliseconds after the upper torso). This is followed by a significantly higher gain of 1000 d/sec from the arms to the bat as the bat releases at a speed of over 2000 degrees per second. Good athlete = 550>750>1000=2000 degrees per second (rotational bat speed)."


"With respect to the acceleration and deceleration in the forward swing, as the player swings the bat the hips slightly lead the sequence, followed immediately by the combined acceleration of the shoulders, arms or hands, and the bat. The hips reach maximum acceleration between 510 and 585 degrees per second of rotation, followed by the shoulders (upper torso) 700 to 900 degrees per second, followed by the hands/arms, 900 to 1150 degrees per second, followed by the bat release speed of between 1750 to 2300 degrees per second. Done effeciently, the hips reach maximum rotation [not acceleration, but most open position] (on a middle plate pitch) when the bat is perpendicular to the straight line from the pitcher. This means at hip rotation of 70 to 85 degrees of rotaton, the shoulders at this point rotate to approximately 65 to 80 degrees or rotation."


“I remember that you have done motionanalysis as well that you said was similar to Zig's findings which are summarized by his posts here in 2002-3.”

Hi Tom

Yes, the Findings from my study with a Motion Analysis Computer concur with Zig’s Findings. However, neither of these Findings in any way support your (and Teacherman’s) contention that shoulder rotation should be restricted or that energy for the swing is not transferred by shoulder rotation.

Zig states, “Good athlete = 550>750>1000=2000 degrees per second (rotational bat speed)." --- This means that during the swing, the angular displacement rate of the hips peak at 550 degrees per second while the shoulders peak at 750 degrees per second. Yet, Teacherman contends that the energy must come from the hips because shoulder rotation is to slow and would result in bat drag.

Tom, you and Teacheman seem to be reading from the same play-book in this discussion. To better clarify your position, would agree or disagree with the Teacherman quotes below?

(A) “You see....the hips rotate. The shoulders do not.”
(B) “Shoulder rotation occuring at the same time as hip rotation simply can not and does not work.
(C) “The hips and shoulders moving together in no way proves the existance of shoulder rotation.”

Jack Mankin


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