Posted by: Jack Mankin (MrBatspeed@aol.com) on Sun Jul 30 13:47:59 2006

>>> Regardless of the speed that is attained with the acceleration principle, the hitter has to be able to control it by effective decelerating the previous body segment or balance and power will be lost. As a result, stopping body segments is more important than getting them going as fast as possible.

think of the car going 45 mph on the road. If the drive suddenly applyis the brakes there is an order of energy release for those things that cannot benefit from the braking. the wheels will slow, the the chasis, the the body, the anything inside the car. anything not nailed down will fly forward once the other parts of the car stop. Some things may begin to fly forward before the car reaches a complete stop, but they velocity of those things will not be as great. this is the same as the hitter who leaks open or doesn't stabilize one leg or the other. <<<

Hi Zig

Our motion studies of the swing produced basically the same data on the acceleration and deceleration of the hips, shoulders, limb joints and bat segments that you found. However, we came to different conclusions regarding the deceleration of the different segments.

You state, “Regardless of the speed that is attained with the acceleration principle, the hitter has to be able to control it by effective decelerating the previous body segment.”
You seem to be saying that for the deceleration of a segment to be effective, the batter must be able to time when the muscles driving the segment are relaxed. – We found no evidence that the batter controlled the deceleration of a segment.

We found the deceleration of one segment was induced from the dynamic load demands of accelerating the next segment. I think Tom Querry refers to this as, “Sucking the energy out of the system.” In other words, the rotational momentum of the segment is depleted to accelerate the next. The greater the load demand (greater work being done), the greater the deceleration rate.

I would also comment that data from tests conducted by five different bat companies conclude that the forces applied at the handle to accelerate the bat to contact in not a factor on the ball’s exit speed from the bat/ball collision. The ball’s exit speed depends on the bat’s mass and its contact velocity. Therefore, the quality of the batter’s mechanics (or Kinematic Sequence) used to accelerate the bat has no bearing on the ball’s exit speed. It is how much bat velocity attained by contact that counts.

I think it’s possible that Adair’s contention that ‘torque (opposing forces applied at the handle) is not a factor in the swing’ may have come from his misreading these bat company reports. -- Note: They did not say that forces applied at the handle were not a factor in acceleration of the bat-head to contact. They said it was not a factor during the bat/ball collision.

One additional note: Zig, there is another factor we should consider in our discussion. -- How much of the deceleration of a segment could be attributed to the contraction of the muscles reaching their limit?

Jack Mankin