Posted by: Jack Mankin (Mrbatspeed@aol.com) on Sun Apr 20 14:04:15 2003

Question/Comment:

Jack,
> >
> > In one of the posts that was deleted in the message board disaster, you defined bottom hand torque (BHT) as:
> >
> > "A swing mechanic that applies torque to the bat by pulling the bottom-hand back around the top-hand -- as opposed to driving the top-hand past the bottom-hand."
> >
> > And I asked the question, "Why can't it be both?"
> >
> > Could you please answer?
> >
> > Thanks,
> > ray porco
>
> ray, I'll put in my 2 cents even though the Q was directed to Jack. I disagree with Jack ( I think someone else did as well). Pulling the bottom hand around the top hand doesn't make any sense (maybe a typo by Jack?). If anything, it's the top hand pushing around the bottom. Anatomy....in the CHP, near the end of the circle (actually, it's roughly a half-circle)is also near the point of contact. For a left handed batter, the hands are headed roughly in the direction of the firstbaseman. To contact the mid/os part of the ball, the hands would have to keep headed in that direction. In order for the bottom hand to go around the top hand, the bottom hand would have to attempt to reverse direction, and redirect toward the 2nd baseman!The bathead would be re-oriented, and contact would be made on the INSIDE part of the ball. In other words, an inside-out swing. Surely this is not what Jack had in mind.
>
> Why not both? True, up to a certain point, both hands are at work. But near contact, the bottom hand acts as an axis for which the top hand will rotate around & finish the job.By contact both hands might very well start to slow down. When I say the top hand finishes the job I'm talking about the role the hand plays in the final orientation of the bathead.This orientation helps dictate what part of the ball is contacted (is, os, mid) which in turn dictates the field the ball goes to. And I submit that an is pitch hit to the pull field will be harder hit than an is pitch hit to the opposite field.

Jack Mankin's reply:

Hi All

Well, it appears the term "Bottom-Hand-Torque" has really raised the hackles of some readers. I can only wonder what the reaction to "Top-Hand-Torque" must be. --- I think I can describe BHT in a less than hundred words. But first, a little background on why I defined the mechanic with that terminology.

For my study of how energy is transferred in the baseball/softball swing, it was taken as a given that the purpose of all swing mechanics was to accelerate the bat-head around to contact in a predictable plane while attaining maximum velocity in the least amount of time. Before those swing mechanics could be accurately defined, it was first necessary to define the forces acting on the bat that generated bat-head acceleration. Once the forces responsible for the acceleration were defined, then the swing mechanics that most efficiently supplied those forces could be defined.

With the aid of high-speed cameras, motion detectors, pressure sensors and a motion-study computer, it was found that there were two forces acting on the bat that generate bat-head acceleration (gravity is not supplied by the batter). One force transferred the body's rotational energy by the angular displacement of the hands (termed - a circular-hand-path). The second force that accelerates the bat-head was torque (causing an object to rotate by forces applied from opposing direction). In the baseball swing, torque is mainly applied to the bat by the push/pull effect of the hands with a minimal amount supplied by wrist action.

Another key finding to come from the study was that two very different types of swing mechanics could apply torque. By far, the most common way to apply torque was for the batter to drive the top-hand past the bottom-hand as the lead-hand slowed. I termed this as linear mechanics because extending the top-hand from initiation produced a straighter hand-path.

The second type of mechanic that applies torque to the bat does not have the batter fully extend the top-hand before contact. The top-hand stays back (elbow in "L" position) and torque is applied by having lead-side rotation pull the bottom-hand (and knob) around the top-hand. I termed this mechanic "Bottom-hand-torque" because it occurs at the 'hook' in the hand-path where the bottom-hand is circling around a slower moving top-hand (rotational transfer mechanics). --- J and Fernando, this mechanic is shown in slow motion from different angles in my instructional video/dvd "The Final Arc ll". So thousands of coaches and player do not rely on a verbal definition - they have studied it in action.

Also, below is a clip from our Video Archives that shows two MLB hitters applying BHT.

Burrell & Bonds BHT mechanics

J, here is my definition --- Bottom-Hand-Torque: "A swing mechanic that applies torque to the bat by pulling the bottom-hand back around the top-hand -- as opposed to driving the top-hand past the bottom-hand.

I am open to suggestions for a better term. But the old standbys "quick hands", "swing down", hit the ball out-in-front", "pop your hips at contact" and etc. just did not seem to be able to accurately define the mechanic we see approaching contact.

Jack Mankin