Posted by: ray porco () on Mon Dec 19 03:02:23 2005

Posted by: Major Dan on Fri May 4 05:58:12 2001

Coach Tom -
You misunderstand one very important point. I am referring to forward movement of the hips BEFORE hip rotation, not during.
If I was not clear on that point I believe it is in part due to others misinterpreting my recent posts. I do not advocate a forward hip slide during rotation. I am suggesting that the forward movement BEFORE rotation adds something to the rotation and consequently to batspeed. I do not believe that is incompatible with what Jack Mankin considers good rotational mechanics. My observations are that the vast majority of major league hitters do exactly that - take forward movement and convert it into a powerful rotational swing.

The whiplike motion I refer to is the kinetic chain. If half the body weight of a 200 lb hitter travels at 3 MPH, even for a few inches, he is creating momentum (mass X velocity = 300). A 32 oz bat (2 lbs) would be swung at 150 MPH (2 X 150) if all that momentum were converted into batspeed.
The kinetic chain works from the bottom up - legs turn hips, hips turn shoulders, shoulders turn arms, arms/hands turn bat. The body is not 100% efficient but the wave of energy travels up the body and out through the bat (measured as bat speed). Larger slower moving parts start the swing. Smaller, lighter faster moving parts (bat) finish the swing. In this way, if energy is conserved, heavier slower parts transfer energy to lighter parts that have to move faster (mass X velocity is equal). A whip works in a similar way as the slow heavy handle's movement is transferred down the ever tapering whip. As mass decreases, speed increases. A 5 MPH handle movement can create tip speeds of hundreds of MPH. A less efficient whip-like energy transfer from forward hip slide through the kinetic chain seems to translate to about 90 - 100 MPH in the best case scenario (best ML hitters).
Yes, bat speed is generated through powerful rotational forces. I am suggesting that the linear body movements that precede this are 'fuel' used to jump start this rotational activity.
Coach Tom, the lower body actions of pitchers and hitters is similar in the sense that the hips lead and linear momentum is converted to rotational/angular momentum BEFORE it travels up the body (kinetic chain) and is converted into incredible hand speed/ball speed.
I hope these smokescreens, as you perceive them, make more sense in this light.