Posted by: Jack Mankin (mrbatspeed@aol.com) on Tue Dec 16 03:24:11 2003

>>> Dear Jack

It should be said that your insites are always interesting and informative however on this we shall see. Principals of rotation of the swung object the effect of the lead foot rotation is due to the angular rotation of the object in a more horizontal plane in baseball then in golf. Not too many golfers hit a ball off a tee that is 3 feet high because if they did then the foot would open up in order to finish the rotation around the horizontal plane.

The lower body movement of a golfer and a baseball player follow the exact same biomenchanical principal of kitematic sequencing. I quote "During the forward swing of all body segments, including the pelvis, upper body, arms and bat/club must accelerate and decelerate in the correct sequence with specific timing, in order to most efficiently transfer energy and accelerate each of the following body segment. In addition to transfering energy across a joint, energy is added by the muscles across that joint. If the timing is wrond the engergy (speed) will be lost.... The correct sequence during the forward swing requires the pelvis to speed up, peak first, then slow down, followed by the upper torso, then the arms and finally the bat/club."

The legs/big muscles lead the swing in golf and baseball. The swing plane of the upperbody and arms determine how and where the feet will finish.

I would encourage any thoughts on these comments <<<

Hi Dave

Thank you for an excellent response. For the most part I agree with your statement. And, I understand that the laws of physics and bio-mechanical principles do not change regardless of changes in the endeavor. However, this does not alter the fact that the lower-body mechanics we teach to optimize the trajectories of the golf swing do not attain the desired result when applied to the baseball swing (or visa versa).

As you pointed out, changes in the angle of the swing plane influence how the feet will finish. I would add that because the contact point is much farther back in golf, and that the wrists roll prior to contact, hip rotation to contact in the golf swing is about half that of the baseball swing. Also, differences in the amount of inertia that must be overcome in the two swings also play a role in changing swing dynamics.

Therefore, the demand for the legs to drive hip rotation is much greater for baseball than golf. All these factors have an influence on the optimum lower-body mechanics required for each swing. Yes, as I stated earlier, there are similarities in the two lower-body mechanics. But differences in the dynamics of the swings demand that there must also be differences in the lower-body mechanics.

Another key difference in the lower-body is the axis of rotation and the way the lead-leg is used in the two swings. In the golf swing, the lead-leg remains fairly straight and the golfer coils around the leg on the upswing to the launch position -- the foot remains planted while the ankle just sways inward. On the downswing, the body uncoils around the posted lead-leg. This places the axis of rotation around the lead-hip.

In the baseball swing, most of the best hitters have ample flex in the lead-knee as they launch their swing. They use the extension of the leg to rotate the lead-hip back toward the catcher at the same rate the back hip is rotating forward. This generates rotation around the center of the body (the spine) -- not the lead-hip. It is much easier to rotate the lead-shoulder back to the 105 degree position when rotating around the spine than it is when rotating around the lead-hip.

Just another thought. -- In golf, maintaining a straight lead-leg during the swing helps maintain a constant divot depth. -- In the baseball swing, using the extension of the lead-leg to aid in pulling the lead-shoulder back to 105, generating the hook in the hand-path. I would not think a golfer would want the hands to be pulled (or hooked) upward at contact from an extending leg -- thus, keep it straighter for golf.

Jack Mankin