Posted by: Jack Mankin (MrBatspeed@aol.com) on Mon Nov 1 12:18:19 2004

>>> Ray,

I actually did go out and purchase the golf paper you recommended some time ago: "Examining the delayed release in the golf swing using computer simulation" by Springings, and Mackenzie, Sports Engineering (2002) 5, 23-32.

According to this paper, page 27, the maximum muscular torque generated by the torso was 112 Newton-meters, for the shoulder joint 87 Nm, and the wrist joint peak torque was 22 Nm, which the authors state compares well with direct measurements on low handicap golfers. Thus, the torques generated by the wrist are rather small compared to the large muscles of the body, which I hope isn't a surprise to anyone.

Of course this is the golf swing, but the baseball swing seemingly can't be appreciably far from this model. Furthermore, as you know, this article does quantify that late wrist release can increase clubhead speed (albeit less than 5%). In particular, it is advocating exactly the opposite of what is shown by Jack in his video: keeping the wrists angle at a 90 degree angle (or even more, as Tom Guerry likes to note) as late as possible, not "casting the fishing pole" at swing initiation as given in the video.

Your excellent reference has cemented, for me, what I had concluded by other reasoning. That wrist torque (i.e., top hand torque and bottom hand torque) is only a small component of the swing and that Dr. Adair's explanation of the whip like action in his book is the correct way of looking at the swing process. Indeed, the last line of your paper reads "In the simulated golf swing, the main source of power delivered to the golfclub originated at the wrist joint as a result of the whip-like kinematics produced by the torso and arms."

Thanks again for the great reference. I don't advocate most people buy it at $30, but for me it was a great reference.

-JJA <<<

Hi JJA & All

JJA's October 31 post raises interesting points that warrants further discussion. His main point contends that since only a small percentage of club-head speed is attained from "wrist torque" in the golf swing, the percentage of bat speed attained from torque (THT + BHT) would also be appreciably small. -- I agree with JJA that the amount of bat speed gained from "wrist torque" in the baseball swing is quite small. In fact, it is even appreciably smaller in the baseball swing than with the golf swing. This is due to the difference in the grip taken in the two swings. The over lapping of the hands in the golf grip allows the wrist to work together in applying torque at the handle, whereas the baseball grip actually restricts "wrist torque."

I have often pointed out that the comparably small muscle groups that control wrist movement could only have a small impact on the bat speed generated - even if the grip allowed unrestricted movement. However, torque applied in the baseball swing (THT & BHT) does not rely on "wrist torque." Torque applied at the handle in the baseball swing results from the push/pull action of the forearms applying force from opposing directions through the hands. The push/pull action of the forearm is driven by the large muscles in the upper back, torso and legs. This results in a large amount of torque being applied at the handle.

Note: (1) The golf grip restricts any push/pull action of the hands and forearms. (2) I have often stated that "pre-launch torque" was a low-energy movement and the un-cocking of the wrist may play a role in accelerating the bat-head back to the launch position. Whereas, THT & BHT are high-energy movements that require the larger muscles in the legs and torso. (3) I will address Adair's flawed swing model as the discussion continues.

Jack Mankin