Posted by: Jack Mankin (MrBatspeed@aol.com) on Wed Sep 12 16:55:08 2001

>>> I think some separation and closing are important to permit both transfer of momentum and rotation around a stationary axis.Turning the body "in one piece" seems to inevitably give a swaying motion rather than ground up rotation/momentum transfer.The amount of separation is probably more dependent on an individuals unique anatomy/physiology.Theoretically,the more separation you create and the faster you "unseparate",the more power you can generate,however,the intricacies of the motor system are much more complex.
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> I would summarize by saying some separation is necessary,but more is not necessarily better.
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> Epstein does believe there is some direct benefit to increased/max separation and states heuristically that more than 30 degrees "torque angle" means more than 30 homers.Of course,these are people who are already surviving in the majors,and I doubt he has done the detailed video analysis you have.He also states that slim build players separate more than the "thick" ones.

Tom - well stated.
To all -
The key concept here IMO is that 'separation' or 'torque angle' is a primary component of transfer mechanics. If the hips and shoulders turn together (unit turn) the shoulders will not turn any faster than the hips. This would result in a low rate of angular displacement of the shoulders. The value of separation is using that separation as part of the kinetic chain to accelerate the shoulders to a greater rate of angular displacement as the hips decelerate. This is done through transfer mechanics. Jack, your question is somewhat loaded. If different amounts of torque angle create the same rate of angular displacement of the shoulders, then there will be no difference in batspeed due to the torque angle. However it may take one body type 20 deg more to get a specific rate of angular displacment of the shoulders than another body type. This could be due to body type, relative strengths and weaknesses of torso muscles, etc.
I think a better question is: Can a hitter increase the rate of angular displacment of the shoulders by increasing torque angle?
I suggest that the answer is probably 'yes' as long as his body transfer that energy. The answer is 'no' after that point where the body is unable to transfer any more than it already is.
I also suggest that many hitters can improve batspeed in this area because many do not have enough separation. I don't see to many who are creating too much/wasted torque angle but it could happen.
I also think hitters can improve batspeed by more efficient transfer mechanics through conditioning and training.
I suspect Epstein's 30 degrees is an approximation but if we take that number as a guideline, then it says that good athletes with efficient transfer mechanics will have major league homerun power with 30 degrees of separation. You can do it with less (strength vs. elasticity) and its hard to get more than 40+ degrees (can't track the ball with your head backwards).
Tom, I think your last response explains all this very well. <<<

Hi Tom & Major Dan

The points made in both of your post are valid and well taken. I think that either "separation" or "unison" hip to shoulder relation taken to the extreme is less productive. --- If we mean by "unison" that the hips and shoulders stay in alignment during rotation, I can think of no one who would advocate it. For the hips and shoulders to remain aligned, would mean that the torque supplied by the legs alone would drive rotation. The powerful muscles the torso would be limited to just keeping the shoulders in line with the rotating hips.

Taking "separation" too far also has limiting consequences. Allowing the hips to open while keeping the shoulders closed means the batter is giving up valuable leg torque angle on a low load movement. Or in other words, the batter gives up valuable leg torque movement on a freewheeling hip motion. Having the hips open (maximum separation) while the shoulders remain closed means the legs will figure less in the equation. They will have expended most of their torque angle and shoulder rotation will rely mainly on contraction of the torso muscles alone. --- This may be sufficient for a lower load shoulder rotation as used in pitching a baseball or swinging a golf club where velocity is more important than power. But swinging a 35 oz wooden bat requires more use of both the legs and the torso (in unison- if you will).

We would all agree that a 20+ degree separation does occur during the inward turn to the launch position. But in my opinion, any further freewheeling of the hips during the stride is not productive. At initiation, both the legs and torso muscles are contracting in "unison" to drive rotation. At the start of the swing there will be another 10+ degrees separation. But that separation is due to overcoming the added inertia of the upper body and accelerating the bat-head - not freewheeling. From that point on, the hips and shoulders rotate simultaneously (in "unison" - may not be the best term).

You may wish to bring up the "rubber band effect" or momentum, I would be happy to discuss them with you.

Jack Mankin