Posted by: JJA () on Mon Nov 8 19:21:53 2004

JJA,
>
> Great response! Best I have seen on this subject. My experiments with a dowel (one I could get a good grip on)were as follows: 50-55 MPH doing Jack's experiment. 80-85 MPH swinging the dowel like a bat. John Elliot, from Jack's second tape had similar results with a bat, but he is much stronger than I am. I cannot swing a bat 85 MPH. My question has allways been: where does the other 30 MPH come from? Many people say it is from hand torque generated at the end of the swing. It will be interesting what you find.
>
> Thanks,
>
> Nick
Nick,

Let me make a few generic comments, and then I will try to answer your question on your batspeed experiment.

After a somewhat convoluted path, it appears that Jack and I agree on some important issues, and disagree on others. Basically, Jack’s view of the swing process is that

1) Circular hand path is an important common of the swing
2) Circular hand path is supplemented by top hand torque and bottom hand torque to generate bat speed. In fact, in Jack’s view, top hand torque and bottom hand torque are the primary contributors to bat speed, more so even than the contributions of the circular hand path.

This is actually remarkably similar in structure (but not content) to Adair’s view on swing dynamics. Adair’s simple model of the swing is

1) The most important element of the swing is due to rotation, i.e., the whip effect.
2) The whip effect is supplemented by the batter stepping into the pitch, i.e. linear translation of the center of mass of the body.

In other words, a major difference between Jack and Adair is that Adair believes linear forces contribute to batspeed, while Jack instead believes that top hand torque and bottom hand torque contribute to batspeed. However, I believe the major difference between the two is Jack’s insistence that top hand torque and bottom hand torque are PRIMARY contributors to batspeed, even more so than circular hand path.

Without even using physics, my argument as to why the whip effect (circular hand path) is the primary effect is easy. Rotation is key to the whip effect. In an efficient swing, the most powerful muscles in the human body rotate the torso and lower body. How can the hands, which are the only ways to apply top hand and bottom hand torque, possibly be anything more than a small fraction of the torque supplied by the lower body and torso? Common sense tells even a physics tyro that the lower body and torso MUST supply the majority of the torque, and thus batspeed through the whip effect.

So, Nick, a few comments about your experiments. The main problem I see is your use of the dowel rather than a bat. It is really important to use a bat if you are trying to draw conclusions about various swing contributors. For example, I can swing a pencil very fast with my hands, probably faster than I could by rotating, but I certainly can’t do the same with a 34 oz bat. So it is very important to do your experiments with a bat rather than some other instrument.

That said, I still think some of your conclusions are valid. I think there are lots of ways to get 75% of the way there, and the effects aren’t necessarily additive. That’s what makes this stuff hard. Control of the experiment is crucial, which is why I want a video of the experiments that Jack performs because the devil is in the details of exactly how the demonstration is performed.

Finally, I still believe I could get 90%+ of the swing speed at least with an open top hand grip as described in an earlier post which eliminates all top hand and bottom hand torque. The key power contributor is rotation, everything else is gravy. As Nyman puts it, “rotate like hell”.

-JJA