Posted by: Jack Mankin (mrbatspeed@aol.com) on Wed May 5 10:53:30 2004

>>> HI Jack

Would you not agree though that the closer to the body (center of gravity) the hands are the faster that they will rotate. For example a figure skater will rotate faster the closer to the center of gravity that they pull in their arms. The same principals should apply to hitting just over a shorter time period.

As an observation of Barry Bonds his hands are closer to his center of gravity through his swing then most players because of his batting stance where he leans over towards the plate with his upper body and his hands pass directly underneath his head. His center of gravity is pushed further towards the plate then most upright batters due to this stance. Can you comment please.

Dave <<<

Hi Dave

Your comment raises interesting points for discussion. Let us cover your figure skater example first. – You are correct in saying that the closer to the body (center of gravity) the hands are, the faster that they will rotate. However, this does not mean that the energy in the hand-path increases as the hands are pulled in tighter. The energy remains fairly constant. The rate of body rotation increases because the resistance to body rotation decreases as the arms and hands are brought closer to the axis of rotation.

Note that the skater developed the energy for rotation with the hands and arms more extended. The wider the hand-path, the more energy required to overcome the increased inertia of the longer moment-arm. Accelerating the hands and arms in a wide path developed greater momentum. As the moment-arm decreases (hands brought in tighter), momentum remained constant while resistance to rotation decreased and therefore, body rotation increased.

What all of this means to the baseball swing is that slower rotation of a wider hand-path produces as much (and often more) energy as faster rotation of a tighter hand-path (Bonds vs Big Mac). One of the main reasons Bonds is successful closer to the plate is because his swing mechanics cause the bat to have a “slicing across the ball” component on inside pitches. This helps to keep pulled balls from hooking foul.

Jack Mankin