Posted by: Jack Mankin (mrbatspeed@aol.com) on Tue Mar 2 00:54:34 2004

>>> Jack,

I read the following from your batspeed research section:

"So, in the swing of a great hitter, what appears to be wrist action is actually the "push - pull" action of the hands generating a large amount of torque. This torque was developed from the large muscle groups and causes the bat head to be greatly accelerated. --- If the batter does not initiate the swing with torque and rotational forces, he will not be able to obtain the position of power required to apply maximum torque to the bat before contact. This is especially true for pitches on the outside part of the plate."


Would you agree that over-gripping the bat can prevent a hitter from being able to get torque? And in regard to the section under truisms and fallacies about "keeping the shoulders in there," one of the things that I think results from this "bad" advice is that the hitter begins to think of the body as two separate segments. Without even thinking about it, I have found that some kids end up having no coordination (for lack of a better word) between there upper and lower body. For example, like you said, their shoulders are not rotating at the same time as their lower body. I usually tell kids that do this to forget about thinking of the body as being divided into upper and lower halves, but to think of the body as one unit. This unit must rotate all at once. This usually gets the kid to understand that his upper and lower body (shoulder/hips) must be in sync and rotating together. Do you think that this is an accurate way to explain this concept? <<<

Hi KSTEVENS

I have found that batters who grip the bat tight are accustom to driving the knob while those that swing the bat-head tend to have looser grips. Gripping the bat, or anything that creates tension, has a negative effect on generating maximum bat speed.

I agree with your statement, “upper and lower body (shoulder/hips) must be in sync and rotating together.” The main power source for the swing is supplied from shoulder rotation. Therefore, the purpose of all lower-body mechanics (legs, hips and torso) is to rotate the shoulders. I have never understood why anyone would think that disengaging the shoulders while the hips rotated would increase bat speed. – Below is a post that might interest you.

##
Re: kinetic chain
Posted by: Jack Mankin (MrBatspeed@aol.com on Mon Sep 24 16:36:01 2001

>>> Hi all. I would like to learn about what is known as the kinetic chain. I heard this was the place to go to ask. I realize the subject may be a far-reaching one, but I'd just like to know the basics. Your help is greatly appreciated. Chris <<<

Hi Chris

Welcome to the site. I refer to the kinetic chain as the mechanics of developing rotation around a stationary axis. Body rotation provides energy for the swing, but how much of that energy is converted into bat speed depends on the efficiency of the batter’s transfer mechanics.

It is quite obvious to anyone who has studied the baseball/softball swing that the hips are ahead of the shoulders or hands at the start of the swing. The hips start to lead the shoulders well before the swing is initiated. In the Frame-by-Frame section of the site (Swing Mechanics) I wrote, “The batter has rotated (inward turn) his lead shoulders away from the pitcher.” So the hips already lead the shoulders by 20 to 30 degrees as the batter prepares his launch position (look at Frame #B).

Frame #C shows that some (not all) batters develop even more separation during their stride. I stated, “The lead knee has started rotating around toward the pitcher;” (not all - after Barry Bonds' stride his lead knee still points more toward the plate than the pitcher). This means the hips now lead the shoulders by approximately 30 degrees. All of this occurred before the swing was fully initiated. From viewing the “Frame-by-Frame” section, everyone should see and understand that the hips lead the shoulders at the “start” of the swing. ---But we must also remember that at the “finish” of the swing, the shoulders will have rotated past (and now lead) the hips. And after full initiation, the hips and shoulders do rotate at the same time. When studying the swing in frame-by-frame motion, you can really see this happening.

I used the term “unison” to denote mechanics that during initiation have all the muscles in the legs and torso are contracting in unison to drive shoulder rotation. This is to distinguish it from “sequential” mechanics where the batter first contracts the leg muscles to rotate the hip (while holding the shoulders back) and then later fire the torso muscles.

Note: There is a 3-stage type of mechanics being taught where the batter is taught to (1) stride, (2) use the leg muscles to fully rotate the hips while keeping the shoulders closed (3) fire the arm and torso muscles to bring the hands and rotate the shoulders. --- I refer to the hips rotating while keeping the shoulders closed (no load hip rotation) as “freewheeling.” For there to be a “kinetic chain” (or rubber-band effect), continuously energy must be supplied from the ground upward to rotate the shoulders. This means, all muscles in the legs and torso must be contracting in “unison,” not “sequentially.”

Although all the muscles are contracting in unison at initiation, the hips will still rotate a few more degrees ahead of the shoulders due to the increased load of accelerating the upper-body mass and overcoming the inertia offered by the bat to acceleration – not from sequential timing.

Jack Mankin