Posted by: tom.guerry (tom.guerry@kp.org) on Mon Jan 20 17:22:30 2003

>>> 4)Mo Vaughn and some other thicker body types fold at the middle - front shoulder toward front knee, then drive the hips forward through that hip/shoulder line with emphasis on the back hip. It is a combo hip thrust and twist. This is a very powerful and quick movement. Bonds does a more elegant version of this.<<<
> >
> > Hi Major Dan
> >
> > We are on the same page. But in your above analysis, I think they (especially Bonds) uses the extension of lead-leg to drive the lead-hip around and back toward the catcher more than driving their back-hip forward. So I would say they emphasis the front-hip more (or at least as much) than the back-hip.
> >
> > Jack Mankin
> >
> I think they both happen. I put more emphasis on the back hip in terms of the force used to 'unfold' the body. The lead leg/front hip plays an equally important role IMO.
> While we both see the same action/motion from the outside view, I feel that the swing originates from the hips and works both down and up. If you 'pop' the hips to start the swing, the back hip drives forward, the lead hip pulls around and the front leg straightens as a result of this.
> "uses the extension of lead-leg to drive the lead-hip around and back toward the catcher" I'd say "drives the lead-hip around... to create lead-leg extension"
>
> We disagree possibly on cause and effect, but we are looking at the same event. I used to teach front heel down to trigger the swing.
> Now I teach to pop the hips from a balanced stance. The front heel rotates into foot plant, but it is a result of the hip action. Looks the same however But I can get consistent results with very little complication/overthink/overteach on my and my students' parts.
>

Some stray thoughts from a voodoo(unqualified) scientist.

This stuff is very non-intuitive,or perhaps it's more accurate to say that it is so intuitive it is difficult to state logically.I suspect a lot of this has to do with the feel of momentum transfer which is a strange thing.

As for the purpose of the stride,one of them is to move the limbs in a synchronized way to assist body motion.I have never gotten a good feel for no-stride personally.

While weight shift may not be a requirement of Jack's mechanical 3 arc model of the swing,it is probably a biomechanical requirement for the human body that has to implement these principles,whether it's via the stretch/shorten cycle or whatever.

I think you can set up weight shift early in the swing(before the hip cocks),and then apply it at front toe touch if you keep the center of gravity moving/dropping along the "target line" beginning shortly after stride foot lift.Then in the meantime the body is stretching and rotating.This stretching then more stretching via "separation" happens while the front foot is still airborne/non-weight bearing.

As the hips are rotating before front toe touch,the body is stretching rotationally/separating.Weight shift/resistance as the front leg bears weight finishes the stretching/loading of the body and initiates "rotational whipping" or momentum transfer to the torso(hips/lower body mass decelerate,torso upper body mass accelerates to conserve momentum in somewhat balanced/closed system).This is the winding/unwinding of the rubber band which is a good cue for me.The swing happens well when you feel this part.

Front heel rotating into footplant sounds like rotation before application of weight shift to me.

Loking briefly at Bonds,Sosa,Kent, and a few others,the level of the head drops gradually then faster until things level out at front foot heel down/launch.Then they stay pretty level until contact.Bonds may come up a little for the high ball towards contact,and out a little for the outside locationLast frame or 2 before contact).

What causes this increasing drop from just before toe touch to front heel down,associated with the THT/drop and tilt part of the swing.The feel I have tells me it's mostly the sretching of the body as the hips open and the upper body forms the box creating separation.This is the last bit of bowing/flexing of the body assisted by weight shift, before it rotates/unwinds/arches in the "launch" phase.

I would think you could only use the energy of weight shift by the resisting/weight bearing action of the front foot.Once this happens,the hips have given up the momentum to the torso and the torso turn is driving things.

The flex(bow)to arch is the middle out action,using the front leg for an initial jumpstart(when weight is born after toe touch) and as a point to set a stable axis of rotation around.I would agree with the hypothesis that the middle/torso is driving leg extension,not vice versa.This(good momentum transfer/hip deceleration/stable axis of rotation/circular handpath/bat already turning) gives the full torso rotation(105+) ofetn snapping the front knee to extension(was it the front knee that disabled Big Mac ?).

If the Dan model is sit to load and stand and turn to hit,I would say you stretch and separate to load.meanwhile you are sitting as you carry the weight forward,then you finish loading at "launch".Then the torso launches the circular/hooking handpath around a stable axis as body goes from bow to arch.

Center of gravity is still during the launch to contact phase as torso rotates around stable axis.I'm not sure what linear vs down/up weight shift means.Maybe if you plotted the center of gravity,it would fall,then stop.(voodoo scientist at work-beware).