Posted by: Mike Myers (mike.myers@bellnexxia.com) on Wed Dec 19 14:18:09 2001

Hi Jack,

I am an engineer. I have been reading your site, and you make a number of salient points re: efficient power generation. I have a few questions/points, however:

1. You indicate in Bat Speed Research (Wrist Action or Torque):

"The large muscles in his legs and back have rotated his hips and shoulders to a point where the belly button and chest are now facing the pitcher. His lead shoulder is now starting to rotate back in the direction of the catcher. This means that the lead arm, and thus the bottom hand, are now being pulling back toward the catcher as the bat approaches contact. --- At the same time the rear shoulder (and top hand) are rotating around toward the pitcher."

This, while possible, does not lead to maximum torque at contact. If the batter ends his rotation facing the pitcher, and contact is at this point with the bat perpendicular to ball trajectory, then the lead shoulder is no longer being powered “back toward the catcher”, but is merely following through with residual waist action. Further, if the batter stops his rotation facing the pitcher, he must actually have decelerated just prior to stopping rotation – again reducing bat speed. Perhaps you can explain this paradox.


2. You indicate in Truisms and Fallacies (You Must Have Quick Hands):

“When referring "Quick Hands", I am mainly concerned with the perceived role of the top hand in the development of bat speed. Hitters are taught to accelerate the bat by driving and extending the top hand back in the direction of the pitcher. But, far from driving the top hand forward, great hitters like Williams and Sosa initiate the swing by pulling with the top hand back toward the catcher. This would be very simular to an archer pulling on a bowstring. The force of the rotating body against the lead arm will quickly accelerate both hands in an arc toward the pitcher. Thus, to maximize the torque that is applied to the bat, the direction of the force of the top hand should not be initiated in the same direction as the bottom hand.”

Agreed.

“Average hitters rotate (or clear out) the shoulders primarily to give the arms a platform to swing from (extend from would be more accurate). This is why average hitters believe that to have power - they must have those powerful arms. This is not the case with great hitters. I can't stress the following point strong enough: DO NOT RELY ON THE MUSCELS OF THE ARMS TO ACCELERATE THE HANDS. --- With Mark McGwire, Sammy Sosa and hitters of their caliber, the role of the hands are to impart the bat with torque (get the bat to rotate about a point between the two hands). Any attempt to force the hands forward ahead of rotation impedes the natural arc and timing of bat head acceleration.
When the burden of overcoming the bats inertia falls on smaller muscles (like those of the arms) the swing will have that tense and jerky look. The huge rotational force generated by the large muscle groups (legs, torso and back) can overwhelm the smaller ones if not supported. --- The smooth, loose, powerful swing of a great hitter is the result of allowing the body's rotation against the lead arm and the bats reaction to torque to accelerate the hands.”


Your articles indicate shoulder and forearm strength is merely incidental to producing bat torque, (and casting for middle-to-outside pitches), and not largely responsible for developed power, as this is left to the larger muscle groups of the “legs and back”. While acknowledging with great hitters “the role of the hands are to impart the bat with torque (get the bat to rotate about a point between the two hands)”, you have nebulously shied from the mechanic of this process, except to show a batter initially with close grip applying opposing forces to the bat handle.

The solution is to utilize the powerful muscles of the upper-arms to produce bat torque. Jack, you have seriously underestimated the role of arm strength in delivering proper bat torque. The lead arm should not merely be “pulled” by the rear shoulder, but, in addition, be pulled with the associated bicep. Conversely, the top hand should be additionally pushed with the associated tricep.

Bat grip is key in this exercise. In all your illustrations, the bat is gripped with both hands close gripped together at the end of the bat. This is incorrect. In order to deliver a proper torque mechanic in the bat with the arms, an axis of rotation must be selected within the bat. One cannot deliver rotational power while gripping close together. There must be a separation of the hands equal to the diameter of the bat at the axis of rotation. This is critical for unleashing huge power in the upper arms. If the hands are gripped too close together, an inefficient shearing force is delivered to the bat, when the goal is to spin the bat. Note: a close grip can apply a torque – but it is inefficient – relying heavily on the wrists to drive rotation.

Imagine a bat revolving about a stationary axis located within the handle, perpendicular to the bat length. Observe, there is a circular region at the hub with diameter equal to thickness of the handle which must be permitted to rotate, by forces external to this region.

Put another way, if you place a car wheel on a table, bolted to the table at its center, will you be able to spin the wheel if you apply opposing forces external to the wheel with a perpendicular distance between the forces less than the diameter of the wheel? No. On the other hand, if you fasten 2 sticks on opposite sides of the tire, with their lengths perpendicular to the tire wall, then you will be able to spin the tire by applying forces perpendicular to these sticks at any point from the tire wall up. This is critical. You will notice ferocious power if you grip with 1 inch hand separation. Note, no more than an inch as this moves the axis of rotation farther up the bat, thereby slowing the bat head. You will feel an ease on contact. This comfortable drive action is applied by arms and, to some extent, wrists. Of course, shoulder rotation is still the strongest component, but arms create substantial additional torque. Outside plate coverage is reduced, however.

The efficiency of rotational mechanics is key to producing optimal power. Do not discount additive arm action in this process. In fact this is why batters lean back on contact – to position the bat such that the bat and body rotation are maximally additive in a single plane. Both centers of rotation should closely coincide.

I am skeptical Big Mac would have achieved his results, particularly his extremely long home runs, without his legendary forearms applying significant torque. There are many major leaguers who exhibit strong torsional mechanics, have lean arms, and hit long home runs, however, nobody has consistently crushed the ball like Mark McGwire in his prime. Even Bonds’ average HR distance, while impressive, is not comparable.

3. In “Rotation and the Stationary Axis”, you indicate:

“The lead knee and leg will rotate the lead hip and shoulder (around the spine) away from the pitcher. Some refer to it as an "inward turn" of the shoulder. A line through the hips and shoulders would now point in the direction of the second baseman. This should bring the hands, center of axis (spine), and pitchers mound in line.”

If both legs apply equal forces to rotate hips about a fixed axis, how can this axis be the spine? It should be the middle of the torso.

Thanks,
Mike.