Posted by: tom.guerry (tom.guerry@kp.org) on Tue Jan 25 15:12:51 2005

>>> The term circular hand path has not come up in the lessons obviously. What I see (naked eye at full speed) is that my son starts with his hands just below his right ear (he's a RH batter), with the bat in a mostly vertical position. As part of his timing mechanism, he "drifts" his hands back toward his right shoulder. This either causes or occurs simultaneously with a slight inward turn of his front/left shoulder, though he is not specifically instructed to do this.
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> His hands do appear to take a circular path, though I find it hard to believe he could take a truly straight path and still make decent contact with the ball. So I'm not sure how reliable this observation is. Are there visual keys I should be looking for: i.e. left/front arm staying tight to chest/rib area, right/back elbow moving down to his side as swing launches, rotate around an axis, straightened front leg at contact, etc?
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> Thanks for your help. <<<
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> Hi Jon
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> I would say from your description that your son’s pre-launch and swing mechanics are on the right track. You have named most of the key components of a good swing. Although one can get a feel for the quality of a batter’s swing with the naked eye, it requires a frame-by-frame video analysis to determine the efficiency of a batter’s mechanics.
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> There is an important biomechanical principle to keep in mind when evaluating a hitter’s mechanics. It states, “When a ballistic motion is initiated, there are trajectories produced that can only be changed at its margins.” In other words, two swings can appear very similar to the naked eye and yet one can be far more productive than the other. Although both swings may appear to have launched the hands into a productive circular path, what
may appear as slight differences occurring during initiation can result in substantial differences by contact.
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> Even with a frame-by-frame analysis, we can see the hands (as a unit) are being accelerated, but we can not see the direction of force the top-hand applies to the bat handle. When the top-hand is pulling rearward with the fingers, the bat-head also accelerates rearward in sync with shoulder rotation. If the batter applies a forward pressure with the palm of the top-hand, the bat-head starts to lag behind shoulder rotation (falling behind the power curve).
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> I use the contact frame to determine the efficiency of the batter’s transfer mechanics. If the batter initiates the swing with the correct forces, the bat-head’s acceleration will stay in sync with shoulder rotation and the bat will be brought to contact as shoulder rotation is depleted. Pushing forward with the top-hand results in the bat-head falling behind the power curve and lagging 30 to 80+ degrees from contact as the shoulders stop their rotation. The batter must then rely on the extension of the arms to bring the bat to
contact.
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> The direction of force applied by the top-hand is also evident in the initiation frame. When the batter is pulling rearward with the fingers, the hands (as a unit) stay back closer to the shoulder and we can see that the rotation of the shoulders is accelerating the hands. When the batter is pushing forward with the palm, the hands will normally start to move away from the shoulder before the lead-shoulder rotates. The more the hands move
away from the shoulder before rotation, the poorer the results.
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> Jack Mankin

Excellent description,Jack !
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