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Re: Leg/LowerBody Mechanics-Pure Speculation

Posted by: Jack Mankin (MrBatspeed@aol.com) on Mon Aug 28 14:18:00 2000

Hi Tom

When discussing lower body mechanics and "weight shift", I think it is significant to point out just how far the arguments have shifted from the original theme supported by noted researchers like Professors Adair of Yale and Kirtpatrick of Stanfort. They agreed that about 50% of bat speed development was due to an angular hand-path. They considered the bat as being swung as if with a rope and therefor "torque" is not a factor in generating bat speed. They hold that the balance (about 50 %) of the bat speed is derived from the transfer of the body's kinetic energy.

As basically described in "The Physics of Baseball" by Robert K. Adair

*** As the swing begins, the batter strides forward transferring his weight from his back leg to a stiff front leg. As the hands accelerate, the force from the reaction of the bat, transmitted through the hands and arms, slows down the body's forward motion and rotation. As the body slows, the hands that had been accelerated to approximately 15 MPH, also slows to a near stop. The body's kinetic energy is then transferred to the bat as forces uncocks the wrist. During this time (as the hands slows and wrist uncock) the kinetic energy that was stored in the body is transferred to bat. This kinetic energy transfer accelerates the bat head from about 40 to 70+ MPH. ***

In my discussions with him, Professor Adair completely discounted torque as a factor in developing bat speed. In his book he states; "A player swings a bat very much like a weight on the end of a rope" and "Conversely, a force at the handle is not transferred to the point of contact," --- He went on to tell me that I should not think of the stride as a "timing step", it should be thought of as a "power step." Because without it, a batter could not develop any power. --- In a letter to me he wrote; "And any batter who would use your "stationary axis" model, taken literally, could not hit a ball past second base."

Here in our little world of internet discussion boards, we are past the "whip analogy" and are debating whether or not and to what degree the stride or "weight shift" contributes to hip rotation. A far cry from the importance given the "power step" by the scientific community. But on the world stage we are but small players and meanwhile the kids are being taught mechanics based on theories of the better known authorities.

Jack Mankin


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