Posted by: Jim (jwelborn@lexcominc.net) on Tue Nov 29 20:42:59 2005

> Hi All
>
> Over the past couple months there have been a good number of threads discussing the role of ‘weight shift’ and ‘hip slide’ in the swing. Most of those posting agree that sliding the hips ahead of the lead-shoulder can set the proper axis tilt for the body to rotate around. Many also believe that the linear momentum attained during the ‘weight shift’ in transferred into hip rotation.
>
> Linear swing mechanics is based on the theory that linear momentum is transferred into hip and bat rotation. Linear advocates like Charlie Lau and Professor Adair have long maintained that hip rotation is induced when weight shift is ‘blocked’ by a firm lead-side. Along this same line of thinking, they also maintain that when the hands are extended linearly, there would be a ‘whip” effect that rotates the bat when the extension of the hands slows.
>
> As I demonstrate in the clip below, there is no ‘whip or pendulum’ effect of the bat-head induced from a linear extension of the hands. As you view the clip, visualize the hips (rather than the bat) sliding forward. We can see that there is no rotation of the bat when its linear momentum is blocked and there is little to no hip rotation induced when a linear weight shift in blocked. – As you view the clip ( http://www.batspeed.com/media/WhipHigh.wmv ), think of the swivel handle on the bat as being the lead-hip-joint sliding to a stop.
>
> Jack Mankin




Jack,

The clip (http://www.batspeed.com/media/WhipHigh.wmv) is an excellent demonstration of your point regarding the blocking of linear motion. I agree that a linear hand path cannot create a “whip” effect and the same would be true of the hips IF linear hip slide were “blocked”.

However, I do not believe that hip slide is blocked or stopped by the firm front side in the way your clip illustrates. One role of the front leg is to redirect the front hip as it approaches its limit and help change linear motion into rotational motion by turning the front hip. In most cases, my pro clips reveal that the hips show detectable hip rotation 1-3 frames BEFORE the forward limit of hip slide is reached. The fact that hip rotation usually begins BEFORE linear hip motion ends is compelling evidence that the front leg redirects the motion of the front hip. One would think that if this relationship did not exist we would never see hip rotation beginning prior to the end of hip slide. In no cases are there stopping or blocking of linear motion and then starting of hip rotation. Linear leads fluidly into rotation.

Think of it as a car driving in a straight line and then turning into a curve. The car doesn’t have to stop in order to turn. Neither does the front hip.

The “whip effect” analogy does not relate to the hips because appendages are not involved as they are with the upper torso and arms.

I do not mean to imply that linear hip slide is the main source of energy created by the hips during rotation. It is not. The interaction of both legs and the torso muscles creates vastly more energy. It does, however, make sense that hip rotation building off of body parts that are already in motion will be stronger than hip rotation that must build off of static body parts.

Jim