Posted by: byront () on Tue Jan 14 07:45:54 2003

Where does "sitting" fit into all of this rotation?
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> > How do you "sit"; "sit" is the cue but what does that mean exactly?
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> > Some people say sit and lean, some say don't arch the back; some sit lower than others; there seems to be different variables. What is the signficance or advantage to sitting?
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> > When in the sequence do you "sit" in relation to what the bat head is doing and in relation to what the pitcher/ball is?
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> > Is "sitting" a cause or an effect?
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> > I could ask more questions but can anybody help or refer me to a reference or use a major league hitter's video clip as an example to explain so I can know what I am suppossed to be looking for?
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> Some thoughts on the "sit to hit" cue.There are many many possible interpretations/implementations for this descriptive cue.To start,you have to have some agreed context or the interpretation can't be meaningfully communicated.So Let's start with Jack's definition of a rotational swing as a series of arcs.
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> 1- the body/torso turns around a stationary axis.
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> 2- tight connection via the arms to the torso drives the handpath in a circle.
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> 3-push/pull/torque is applied by the hands throughout the swing,beginning the bat turning before the torso turn starts the handpath circle.This arc of the bat is the "final arc".
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> All these things need to happen to create the "short" rotational swing,which has significant differences from the "long" rotational of golf,for example.The short rotational swing is better for hitting because the most important aspect of hitting mechanics is to minimize timing error.The way the human body works,motor programs need to be learned which can be automatically executed faster than conscious control will allow.The shorter the path of the swing(roughly path of sweetspot from launch to point of contact) and the faster the path is traversed,the lower the timing error because the body can predict the duration of swing more accurately the faster the swing is taken(motor learning principles).Contact needs to occur before deceleration for timing precision.
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> So according to Jack,rotational mechanics implement these 3 arcs,and anything else would be some degree of flaw that makes the swing "linear" or non-rotational.Jack points out that degree of weight shift/length of stride is not the factor that determines whether a swing is linear or rotational,however,after the torso rotation has started to drive the circular handpath("launch") the axis must be stable with no ongoing weight shift.
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> So there can be weight shift associated with the rotational swing that does not make the swing linear,but why should there be ?
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> If we consider the model above a mechanical model,it may be that the human body must require some type of weight shift to implement these mechanical principles.In other words,there may be a BIOmechanical swing model of how the rotational swing is taken that includes a requirement for weight shift.So you would have to look at video and see how this could be explained.Remember,having weight shift does not make a swing linear,violating the mechanics of the 3 arcs does.
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> One further mechanical principle pointed out by Paul Nyman is that the hips should be turning at maximum velocity when the shoulders start turning to transfer momentum efficiently.
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> Tom's hypothetical Biomechanical "phases" of the swing(if you buy in to the above):
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> 1-hip cock: The first phase of the swing ends with the cocking of the hip shortly after pitch release but before the given pitch is recognized.Prior to this the body is rotated back a little with some flexing of the body as the hands come into the center.If you take the example of Sosa and Bonds,they have the 2-piece stride.They bring the stride foot in prior to release which leaves them with a narrow base,and the center of gravity will go forward allowing them to "fall" like the old idea of the tall and fall pitcher(Weight shift is also vital in pitching,but mechanical phases and how it fits are different).Then as the second piece of the stride starts with the foot going forward,the hip cocks with the internal rotation of the limbs,especially the front leg(inward turn of knee,front foot turns back and leads with heel) and the back arm(bat cocks toward pitcher and up or out some,vertical bat preferred).
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> Now during the rest of the swing,the center of gravity will comtinue its fall until some reistance is applied(as front toe touches) so that the axis of rotation is set at "launch"(after front heel drops).
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> 2- stretch: the front leg goes out and the internally rotated back arm goes back/up via scap loading so that the back elbow is elevated.The bat begins to turn(uncock)and fall into the power plane that the torso will turn in.By this time 3D pitch location is being recognized and a particular "motor program" is being assembled/matched and automatically executed based on prior experience.Over phases 2 and 3,the right posture adjustment and swing radius will be set for the particular pitch.
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> 3-separation: hip uncocks from middle out followed by external rotation of back elbow to fixed position in "slot" while front leg externally rotates.Back leg and front arm internally rotate.Hip rotation/uncocking starts prior to front toe touch in most cases,then the front toe touches,then the heel drops.Epstein cues work here(as descriptions of desired belly up to the plate and make history on inside part of plate type of short rotational swing with emphasis on good body turn and short swing radius to be quick to ball with good plate coverage).The front foot lands open.The as the front heel drops,the back shoulder dips("drop and tilt").Separation is maximum at or just before the front heel is down(better to land on ball of foot to set up "resistance").
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> 4-"launch":as stride foot begins to bear weight,the ongoing dropping forward of the center of gravity is resisted(body already rotating).This is similar to Coach C's "golden moment" in golf.Not a "linear" move,but a storing and releasing of energy that was set up earlier in the swing as the center of gravity continued to move /drop while these other motions have proceeded.Posture and axis are set,hips accelerate to maximum velocity,then decelerate as energy goes up to turn torso.A lot of complicated/superimposed motions with a characteristic feel.The head stays back and down as the body bends(arches) at the waist.The "box" has been formed by the arms providing tight connection as part of the drop and tilt.Now as the torso "launches",the front elbow will work in(another)"slot" as mentioned by Epstein,depending on the angle of the rotating torso.The feel is "working down" for high balls(not much bend at waist) and "working the elbow up" for low balls(bend at waist to match plane for low ball).The best swing is the adjustment you make for the given pitch as Mike says.
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> So sitting is fairly complex.Turn back some and start the center of gravity going forward on line(Don't adjust by striding in or out),cock the hip,stretch out,uncock the hip,set up the torso angle and axis of rotation while keeping the center of gravity falling into heel drop.
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> Where can you look for this on video-
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> One poor man's source of clips is the home run derby.Sure,players change their swings,but it only exaggerates what they already do to make it easier to see.Good clips last year for Giambi and Sosa.Other less in depth ones for Bonds,Arod,Berkman,etc.etc.The slow mo shots of Giambi and Sosa are at 90 frames persecond,so you can see this in detail by playing one frame at a time forward and back.
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> Giambi,for example(30 frames persecond)pitchers throwing about 60-70 mph from screen in front of mound,15 frames from release to contact):hip cocked about 3rd frame after release,stretch for 5 frames;separation/drop and tilt/THT 2 frames,torso turns 5 frames to contact.

Tom,

Great post! When I watch video I see hitters turn their back knee in -- their back knee is already flexed before they turn and during and after the turn their knee stays flexed, BUT I do not see any conscious or discernable frame where they "SIT" or the knee is intentionally being taken further to the ground. What do you see? Are the hitters suppossed to actually be sitting or lowering their back knees to the ground as the hips rotate? BT