Posted by: Dave P () on Thu Mar 1 12:07:39 2007

> >>> Thanks for reposting.
>
> I think the chp/connection needs to be in place as the hips decelerate which is somewhat after the shoulders have turned with the torso.
>
> This may be seen about when the back toe starts to drag on players who don't keep their axis leaned back too much. <<<
>
> Hi Tom
>
> Once again, I think we are in agreement. You state, “as the hips decelerate which is somewhat after the shoulders have turned with the torso.” -- I take this to mean that you agree that the hips and shoulders do rotate in unison after hip-cock. There is a theory that basically states that hip rotation is first accelerated to attain maximum stretching the torso muscles. Shoulder rotation is induces once the hips reach maximum acceleration and begins to “decelerate.”
>
> If I am not mistaken, this is the basis of the “X factor” in the golf swing – the more the hips rotate while the shoulders remain fixed, the greater the “X factor” and thus the more powerful the shoulder rotation. This would mean that the hips should be approaching open before the shoulders rotate. This may be true for the golf swing. However, my study of a hundred or so over-head views of MLB swings did not support this theory for the baseball swing.
>
> These over-head views showed that just before the swing is initiated, the hips cock open about 20 degrees. From that point on (hands starting to move into CHP), the hips and the shoulders accelerate in unison. This clip of Pete Rose -- http://www.youthbaseballcoaching.com/mpg/Rose.mpeg – is fairly indicative of what I observed in those clips.
>
> Note how the hips and shoulders are rotating together. Shoulder rotation did not wait until hip rotation maximized and begin to “decelerate.”
>
> Jack Mankin

Hi Jack

Jack you are over simplisizing the mechanic behind the x factor stretch. The hips maximum rotational velocity is before the shoulders maximum rotational velocity and the hips rotational velocity is decreasing while the shoulders are increasing. Video can not measure rotational velocities only by a system like that on Skills Technology or simular computer monitered device can you accurately measure this.

Take note that the hips rotate at a slower rate then the shoulders so in your video the hips would have to lead the shoulders if they are to be open near the same time. Therefore the further the hips can rotate before allowing the shoulders to rotate the faster the shoulders must rotate in order to catch up. I believe this is what you call linkage. To put it another way the hips must begin to decelerate before the shoulders hit maximum rotational speed or the combination of the two body parts would cause the hitter to 'spin out' or overrotate as there is no portion of the body that can help declerate the bat. This is a key factor in the casting of the hands but that is another discussion.

Jack if you download the skill technologies program you can look at the graphs of rotational speeds and x factor stretch. They can be very enlightening.

I found a quote in a book the other day about Hank Aaron. In the quote a reporter was talking about the fact that the coaches of Hank's team where flappergasted at the fact that in photos of Aaron's swing his back foot was off the ground when he made contact with the ball (not bug squishing). Yet 50 years later when the Detroit Tigers make it to the World seires and you see the video of the same thing it was a new concept.

New technology opens the eyes to more percise analysis of the same motions and if we open our minds to what our eyes see we will learn more then we knew before.

Dave P