Posted by: Major Dan (markj89@charter.net) on Thu Mar 29 07:16:39 2001

I have a masters in biomechanics from the university of cincinnati. i have study the weight shift in golf and baseball using force platforms and the peak motus system for my final college term paper. mass: is the force pulling towards
> > > the ground. weight: is mass in motion. center of mass is an objects center in which it pulls down.during rotation this is the line of action in which we rotate around. center of gravity is the weight we use to balance. during rotation this "balance weight" shifts from the back side to the front side, in fact, while on weight shift platforms the baseball player would gain weight in his front foot, up to 110% in body mass. so as i states before, the is a linear weight shift from front side to back side. tested using wavi weight shift system,and sport balance platformsw/the peak motus system.
> > > was not saying that a player should jump at the ball or not rotate.but there is linear weight shift in rotational mechanics.so if my words make no sense, then maybe you should take a physics class. video can not measure ground forces.
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> > hit nut-
> > your post is interesting. I am having some trouble reading it due to abbreviations, partial sentences, misspellings, etc. I don't mean to criticize, I think you have something of value but can't figure out everything you are trying to say.
> >
> > I am confused by what you said in consecutive sentences:
> > "during rotation this "balance weight" shifts from the back side to the front side, "
> > "the[re]sp! is a linear weight shift from front side to back side. "
> >
> > did you find weight shift back to front or front to back during rotation, or am I misreading this?
> > Could you take some extra time and explain in more detail what you did and what you found in your study? It seems very valuable but is too much information to fit into a small paragraph.
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> the center of gravity of an oject is a point at which all of the object's weight maybe conceived as being concentrated. the center of mass is the balance point. take a baseball bat for example, horizontally balance it on your index finger, your finger is the center of mass, the barrel is center of gravity. if you were to cut the bat in half were your index finger was placed, and weigh them both sides would not weigh the same.because the object is not symmetrical. know balance the bat again, and spin it around it's "center of mass" take your other hand and stop the bat's barrel,
> was there weight rotating into your hand???
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> the baseball swing is not a symmetrical motion
> the human body is not symmetrical on all sides
> when a players lead foot lands,they are loaded with the majority of their weight on their back foot this is now their center of gravity.while the middle of the head would represnt center of mass.
> when a player rotates they move the center of gravity around their center of mass. taking weight from their back side to their front side. on weight shift platforms a players weight is back as much as 90% (when the stride ends),with out jumping at the ball or moving center of mass.at contact a player will "rotate" 110% weight into his front side. simply put there is a weight dramatic shift during hip rotation. not very few good hitters and power hitters push off w/their
> back foot, this would change center of mass.
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> please forgive any type O's

You are the master of type O's . I hope you had someone edit and type your masters dissertation for you
If what you are saying is true, then the reason the front leg firms up is to support all the weight being put onto it during this internal weight shift. Is that true?
Why do I see many hitters move their heads/upper body backward a few inches as the bat moves toward contact? Wouldn't this move the center of gravity backward?
I have seen clips of Aaron and Ruth (pretty good hitters) who had very long strides, pushed off their back foot and had a pronounced backward upper body movement as the front leg straightened - upper body vertical to in a line with the straight front leg.
Can you explain how that works in conjunction with the internal weight shift you describe?
Is 'internal weight shift' a proper term/description to use?

Sorry to pepper you with questions, but I am intrigued by your post and want to draw out more detail.