Posted by: tom.guerry (tom.guerry@kp.org) on Sat Mar 5 16:42:09 2005

Sorry the last LONG post got garbled (more garbled than usual because software started not permitting editing-editing would be a good feature).Here is a somewhat corrected edition of the same post.Warning ! long and boring,read at own risk.

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Still looking forward to search feature to review Jack's info about motionanalysis and centers of rotation.From what Jack says here,I believe I would agree more with Shawns position that some linear "weight shift" momentum is necessarily converted to boost/support/assist rotation while the body is still loading/coiling.

I would suggest thinking of the motion as a "swing" by which is meant it is mainly a load motion and an unload motion,but complicated by the fact that these 2 motions overlap.This means that the upper body is still loading after the unloading motion has started from the middle out as the hips turn open.Perhaps even more accurately,both motions start middle out,the load motion first,then the unload motion with ongoing upper body loading which maxes out and reverses (unload/"launch") only after the middle out unload/"hip turn" has been accelerated to maximum turning velocity by the boost from "blocking" weight shift with the front leg to enable the linear momentum to be captured as additional rotational momentum that finishes rotational twist/coil/load.

Jack makes a very important point in that the hips must already be somewhat turned "open" if such "blocking" is going to result in the boost of "counterclockwise"("opening")directed hip turn that is faster/quicker than the simultaneous/synchronized turn of the upper torso (which also turns in a slightly different plane),therefore creating a last quick bit of load/coil/twist that is most efficient in unloading (?using primarily tissue elasticity type properties as opposed to slower muscular contraction/force production) to create a swing maximized for quickness (as opposed to strictly being optimized for max batspeed-whatever the max batspeed is,this should occur just at contact "ideally"/theoretically).

While the arm/scap action/sequence that leads loading and constitutes "transfer mechanics" differs somewhat between golf and hitting,the basic principles and sequences are the same and more widely/better understood in golf.

In golf the importance of "rotation" being supported by the front leg as a base is well understood.Otherwise,the swing is greatly degraded by "reverse pivoting" (weight going backto back leg as rotation progresses or never getting to front leg) which also means the hips rotate by "spinning" which prevents efficient
staged transfer of momentum into the torso and limits transformation into batspeed/quickness.

In golf,it is known that one of the keys to preventing "spinout"/reverse pivot is the right sequence where the hips slide forward ("weight shifts forward") before the hips turn open.Then the weight stays forward and arm/club action is well synched (which is another detailed discussion).

To further understand the requirements of rotating well it also needs to be appreciated that by "rotation",what is usually being described is NOT just "unloading" but the overlap of middle out unloading which is superimposed on the midddle out loading that is already underway.How"weight shifts" during this crucial/complex time to optimize the dynamics of loading/unloading is best described in the golf literature as "x factor stretch",a last quick stretch of the torso muscles increasing the separation/angle between hip position and shoulder position ("torque angle" as defined by Epstein/"x factor" as defined in golf).

Further understanding also requires some agreement about how to describe balance/"weight shift" which is incredibly complex.I would simplify this by saying that "weight shift" could be used only to describe which foot is bearing how much of the load at any time.Center of gravity position might be though of as relating to how momentum is being created and transferred.Center of gravity and how it is changing might be best though of as where the head is in relation to the belly button or belt buckle.

Again,golf and hitting are similar.For hitting:

Start with weight fairly evenly distributed (about 50-50/same amount of weight on each foot). While "preloading" (starting loaded up with most weight on the back foot) CAN work, I believe it is suboptimal in hitting as it is in golf because it makes the initial start of the loading motion inconsistent.It is hardly EVER done in good golfers and while many do it in hitting,Williams among others discouraged "pre-load" see pp.45-6 of SCIENCE OF HITTING with Williams advice to Ken Harrelson.

Next,the transition from "rhythmic preswing activity" to the actual beginning of the middle out load program starts middle out supported by the "negative move" which means the weight is shifted back so the back foot begins to support most and eventualy all of the weight (assuming you take a stride in hitting).This does not mean the "center of gravity" has to move back,but it can.The back hip needs to be "stable" so the body can rotate/turn back without encouraging excessive "sway".

Next the stride foot is lifted and the "hip cocked",Which means all weight is now on the back foot in hitting.


Next the "center of gravity" goes forward as the hands are cocked.This handload/hand cock is done primarily by the back scap pinching toward the spine which centers the bat and it is synchronized with the legs spreading apart/knees spreading.Hip cock has resulted in overall body muscle tone/stable configuration (Dixon's "torso activation") so that the lower body/stride leg is "carried forward" with the hips leading.All weight still on back foot.Head behind or even with belly button/belt buckle.In addition the player sits/body squats as the center of gravity goes forward and down.

At this point the middle out unloading program is ready to superimpose over the ongoing loading program.The weight in the sense of the body's center of gravity is going forward making linear momentum available.The front foot is still off the ground.Just as in golf,the hips are going forward on a line before the hips have begun to turn open,before the unload program supervenes/initiates.

The next "overlapping" part of the sequence requires the hips to turn open (start of middle out unload) BEFORE the front foot blocks or resists.In this way,when the subsequent blocking occurs,the hips will be somewhat open to result in/permit boost when front foot blocking/resistance occurs transforming "linear" momrntum into angular momentum.This is probably as close to and absolute sequence requirement as there is.

While the hips turn open,the upper body 2 armed "box forming"/ bat uncocking/"preplaunch tht" is synched so the bat is being turned permitting the loading program to continue as the unload programs gets underway so the torso is coiled-"winding the rubber band as you stride to toe touch with the weight slightly forward" as Epstein says.Still no blocking/weight bearing by front foot.Still hips leading/head at or behind belly button/belt buckle.Hips turned open.Hands back.Bat uncocking.

The next phase is the creation of last quick TORSO coil/stretch (xfactor stretch) while load/unload motions overlap with coil/uncoil working up torso to stay in sequence before driving the shoulder arm bat link at launch.

Front foot bears weight(weight "shifts" to front foot).Blocking of forward motion of center of gravity converts linear momentum to angular/rotational momentum by acceleration of hip turning open.Upper body still "stays back" because at same time shoulders "tilt" as head comes forward to or past belly button/belt buckle.Center of gravity continues down and forward until fully blocked at time of maximum torso coil/end of load cycle at about "bat lag" position.This is the equivalent of Jack's "tht at launch".Same as maxing out of "xfactor stretch" in the down swing in golf."Front side stretch" is maxed out.

My perhaps idiosyncratic belief is the the "weight shift" linear momentum/center of gravity motion is captured by BOTH the upper and lower body to accentuate last quick coil that permits the most efficient launch and that the upper body/scap/arm action is the dominant organizer of this overall action when it comes to learning the motion.

So in summary,"tht at launch" or "drop and tilt" are the creation of the last necessary quick torso coil which require the conversion of linear momentum to rotational momentum.


Even if you look at Bagwell,note that his bellybutton is going forward.The exact position of the feet is not consistent.

Another key feature of the sequence is that the knees need to spread and stay spread as mentioned above because "hip turn" is driven by thighs and pelvis and is ineffective if the thighs are not spread to provide leverage.The feet are important as a base,but positon is not consistent/essential.The last bit of coil/twist/load happens with the weigh almost entirely on the front foot with the foot then creating a base for control of subsequent unloading.

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