Posted by: Mike Myers (mike.myers@bellnexxia.com) on Thu Feb 6 15:11:22 2003

> When I mentioned bending at the waist,I am talking about more or less flex of the lower spine to adjust the swing plane to match the low or high pitch,given that you are already limiting yourself to/looking inside or out half.I believe "weathervaning" is a "cue"/swing key/marker for this as an image of what the right spine angle/bend at waist is going to feel like later in the swing.Set spine angle at launch and for the most part(not absolutely)maintain spine angle through contact as recommended in golf teaching.
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> > > The timing inside vs out is different enough that it's better to be looking one way or another.The adjustmant for in or out feels to me like it is a handpath radius adjustment depending on how much stretch is set up before launch.Outside pitch has relatively more stretch(more bend comes out of front arm) before launch and later "launch"(torso starts driving handpath slightly later) creating what Jack calls a "high load" situation.Outside pitch "gets deeper",but this cue should be interpreted in a timing sense(relative delay of launch while additional stretching lengthens swing radius)rather than as letting contact happen deep.You are not trying to go the other way.You are trying to start/"launch" later and inspite of higher load,still making contact perpendicualar to flight of pitch.This requires accentuation of how much the bat is turning already before/at "launch"(accentuation of tht).More stretch/longer swing radius/more bat turn before launch to adjust outside which gives significantly different timing.
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> > Torso tilt back is normal in a very powerful swing. This is simply a consequence of Newton's third law: FAonB=FBonA.
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> > http://theory.uwinnipeg.ca/mod_tech/node24.html
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> > If you are moving the bat forward with tremendous force, then the bat will push back and tilt the body with equivalent force. This is not "leaning back", but being pushed back.
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> > Mike.
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> Thanks Mike.
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> It is also important to take into account the biomechanics and motor program aspects of the motion.These are "ballistic" events(acceleration through large range of motion to "escape velocity").They are too fast for "conscious" control).The body recognizes the target and begins on the fly execution of a matching collision program automatically(once learned).The trajectories are set with adjustment more and more limited as the swing proceeds.How much lean back there is/how much reactive forces can be seen depend on decisions and motions much earlier in the swing.While there may sometimes be lean back,sometimes there isn't.Forces cancel and damp out.
> Getting a handle on pitch to pitch location adjustments and how they affect body posture is very complex.The simplest approach would probably be to study a single hitter with many repititions at all locations(including pitch velocity as part of 3D location/recognition and probably in conjunction with ground force plates.Emg seems like overkill but may be necessary.could be hard to find a guinea pig).
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> Even in this situation,cause and effect can be very tricky to sort out.
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> Taking a purely or too physical approach to mechanics results in many inadequate assumptions and models that really don't apply to guiding analysis and learning of the swing.For example,Adair's swing model,while he considers it "tractable" is pretty useless to the hitter.Very hard to interpret and apply as Jack has pointed out here.

Tom,

There are many different swing patterns and associated biomechanics.

I'm simply indicating torso fall back on or just before contact is not a conscious decision to lean away from the pitcher.

It is a natural consequence of having a loose torso, and applying tremendous forward (relative to torso) force on the bat handle. This indicates an extremely powerful swing, caused by force components of all body parts culminating maximally in the hands/bat handle.

Observe Bonds.

Mike.