Posted by: george stanley (saint_george13@yahoo.com) on Wed Jan 30 17:02:27 2008

> > Hi All
> >
> > How that we have discussed the <a href="http://www.batspeed.com/messageboard/119313.html"> Weight Shift - Truism or Fallacy</a --
> >
> > question, how let us turn our attention to discussing the principles that induce hip rotation. I will open the discussion by asking the following question.
> >
> > Truism or Fallacy – When the forward movement of the body gained during the stride is blocked by the lead-leg, the linear momentum attained causes the back-hip to rotate around the blocked front- hip – like a gate swinging on hinges?
> >
> > I addressed the above issue in an earlier post. I am placing an excerpt from that post below along with a supporting video clip. You may disagree with my conclusion. I only ask that you provide supporting evidence for your disagreement.
> >
> > (Excerpt from earlier post)
> >
> > Your post raises a question that has been debated for decades – What forces are at work that induces hip rotation? – On this question, the gurus are divided into 3 main camps.
> >
> > Camp (1) – As the batter strides, he transferees his weight forward to a firm (posted) front side. As the linear progression of the hips is blocked, its linear momentum is transferred into rotational momentum that causes the back-hip to rotate around the blocked front-hip. – (Axis of hip rotation is around the front-hip.)
> >
> > Guru, the theory of your post would fit into this camp. A longer stride generates greater linear momentum that produces a more powerful rotation of the hips.
> >
> > Camp (2) – The Middle-Out Theory. -- As I understand it, this theory contends that hip rotation is induced solely from the contraction of the muscles in the pelvic region. The legs contribute little or nothing. It is hip rotation that straightens the lead-leg and forces the “L” in the back-leg. -- This would seem to downplay the importance of weight-shift. – (Axis of hip rotation would be around the center of the hips – the base of the spine)
> >
> > Camp (3) – This theory contends that hip rotation is induced from a combination of muscle contractions in the pelvic region and torque supplied from the legs applying force from opposing directions (back-leg driving forward – front-leg pushing rearward). This theory also downplays the need for linear weight shift to induce hip rotation. (Axis of rotation – the base of the spine)
> >
> > I am in Camp (3). I do not think the blocking of linear momentum is transferred into rotational momentum. Therefore, I do not think the length of a batter’s stride or the amount of momentum derived is a major factor in generating hip rotation. – I will explain why below.
> >
> > The same physics principle that governs the rotation of a bat about a point also governs the rotation of the hips about a point. – For decades, we were told that the batter’s hands should applied force down the length of the bat (knob first). We were told that once the linear progression of the bat was blocked (slowed to a near stop), its linear momentum would be transferred in rotational momentum, which would accelerate the bat-head around to contact ( the “Whip” effect).
> >
> > As this clip - <a href="http://www.batspeed.com/media/WhipHigh.wmv ">No Whip Effect</a
> > -- demonstrates, there is little to no transfer of linear momentum into rotational momentum to accelerate the bat-head as the hand’s linear progression is blocked. – The same principle holds true with hip rotation. -- There is little to no transfer of linear momentum into rotational momentum to induce hip rotation as the hip’s linear progression is blocked.
> >
> > Supporting video clip –
> > <a href="http://www.batspeed.com/media/Giambi_rotation_momentum.wmv">What induces hip rotation?</a --
> >
> >
> > Jack Mankin
>
>
> Jack,
>
> Camp 3, "(back-leg driving forward – front-leg pushing rearward). This theory also downplays the need for linear weight shift to induce hip rotation. (Axis of rotation – the base of the spine)".
>
> "back-leg driving forward"-linear move into front leg.
> "front-leg pushing rearward"-blocked front leg
>
> The weight shift doesn't happen in the stride it happens at "go". The front hip has already cleared by the front leg opening and pushing the hip back and out of the way (blocked front leg). The rear hip is driven forward by pushing off of the back foot along with contracting the muscles in the pelvic area (linear move). The blocked front leg stops the forward movement aiding in rotational energy. Without the back foot push you would merely be spinning.
>
> IMO it is not like a gate because you are not rotating around the front hip but you are pushing forward off of the back leg into an off centered front hip and blocked leg.
>
> Graylon


hello, jack!

good questions being asked... answers not so definitive as to be objectively satisfactory in answering ALL aspects of the question asked..

may i quote BILL JAMES, the all-time omniscient statistical king of all he surveys... here's what he had to say about all of us so=called baseball furus in a magazine article...

among what he calls the "interlocking dramas" of mlb,(my translation reads "political horse-droppings") BILL JAMES (yes bill james is going to come to my defense) looks for things to quantify. the godfather of "sabremetrics" joined the red sox in 03, implmenting stats such as "range factor" that helped mgmnt spot overlooked players... and win its first world series. HOW CAN YOU GET THE JOB??
james, who learned stats from bb cards as a kid, RECOMMENDS KNOWING BB HISTORY, STUDYING THE SPORT OBJECTIVELY, AND PUBLISHING ORIGINAL RESEARCH. here is the nitty and the gritty....and i quote bill james

"MY VIEW OF THE WORLD, WHETHER BB OR PHYSICS (hmmm, mentioning physics... imagine that!) THERE ARE OCEANS OF IGNORANCE AND SMALL PONDS OF KNOWLEDGE" ... when asked if there was room for another stat freak in the bb ocean:

"ABSOLUTELY....WE DON'T KNOW NOTHIN !!!!" when asked for prerequesites:

"SKEPTICISM ABOUT THE STATUS QUO"

... so that's what as eminent an authority in baseball as there is to be found or heard or seen ANYWHERE... BILL JAMES !!..
sez about all of us brilliant baseball players & coaches.. (you and i included!) yep.. you can look it up

1st question:
FALLACY !!!!
if as you say the back hip were to to rotate about the front hip...
as in a gate swinging.. that would indicate to me that the back foot has to leave the ground in order for that to happen... which it does NOT do in my perfect swing world.. you would have the front hip as the axis around which the back hip would rotate... NOT !!! at some point the back lef would have to come off the ground.. which is not a good thing.

the reality is that BOTH hips should be rotating around the spinal column axis.. once the front foot touches down, the whole movement sequence can be described as a ballet movement... all the moving parts have to be in synch with the others for a successful swing.. BOTH feet should be torqueing or screwing into the ground at the same time, which will generate the greatest amount of lower body torque... WHICH IS WHERE THE GREATEST SOURCE OF POWER LIES!!!
before i pick a camp number, consider this mindset:
ANY ACTION IMPLEMENTED WHICH SLOWS DOWN LOWER BODY TORQUE DIMINISHES BATSPEED.. now looking at

CAMP #1: W R O N G !!!
endorses rotating the back hip around the front hip... NOT!! if the front hip is the axis around which the back hip revolves, then at some point the back leg & foot must come up off the ground... now you are on just your front leg, & you end up facing 3B (RH hitter) when you are done swinging... not a pretty picture!

also.. this statement: "A longer stride generates greater linear momentum that produces a more powerful rotation of the hips".. first part- NOT REALLY... the 2nd part is JUST FLAT OUT WRONG!!
a longer stride WILL generate greater linear momentum... BUT THERE IS A POINT AT WHICH THE STRIDE BECOMES TOO LONG... AS A RESULT, THE BASE BECOMES TOO LONG TO GENERATE THE MAXIMUM TORQUE QUOTIENT.. if a hitter were to stride just as far as he could before touching down his front foot... he would end up with his legs spread so far apart that he would be helpless to torque his hips any appreciable distance in order to generate maximum power.. surely you must see that a shorter base will allow greater hip rotation..
FACT: A SHORT BASE WITH THE FEET SHOULDER WIDTH WILL ALLOW THE GREATEST CONTROL & SPEED TO THE WEIGHT SHIFT PROCESS BY WHICH YOU GET IT GOING.. A SHORT STRIDE WILL ALLOW THE HITTER TO PUSH OFF THE BACK FOOT/LEG/HIP WHICH IS WHERE THE REAL POWER LIES..FROM THERE THE QUICKER THE HITTER LANDS & BEGINS TO TORQUE THE LOWER BODY, THE QUICKER HE STARTS TO GENERATE POWER TO THE UPPER BODY, THE GREATER THE POWER HE WILL GENERATE.. THE SHORTER THE BASE, THE MORE CIRCULAR MOVEMENT BY THE HIPS, THE GREATER THE SPEED GENERATED.. the longer the base, the less movement allowed to the hips, the slower you go, the more you diminish the batspeed. the best stride distance is a middle ground on the short side rather than the long side.

CAMP #2: W R O N G !!!
THE LEGS CONTRIBUTE LITTLE OR NOTHING!?!?!? HUH?!?!?!
if that is true, then sit on a barstool & see how well you hit the ball..how can ANYONE believe that the legs which are the strongest muscles in your body are of no use when it comes to generating batspeed?!?! the power generated comes from the ground.. where the feet meet the ground is where MOST of the power is generated... IT DOES NOT COME FROM THIN AIR!!! HELLO?!? WHEN YOU PUSH YOUR FEET & LEGS OFF THE GROUND, THIS IS WHERE THE POWER IS INITIATED!! to say otherwise would be to say the legs are no use whatsoever.. so sit on a barstool & see how much power you can generate with just you upper body... not HARDLY AT ALL, CERTAINLY NOT ANYWHERE NEAR AS MUCH AS WHEN YOUR FEET & LEGS ARE UTILIZED TO GENERATE LOWER BODY TORQUE..

CAMP#3: C O R R E C T !!!... for the most part.
i do object to your compartmentalizing the swing, & breaking it into several phases.. it is a continuopus movement which is very difficult to break down or segment... to do so is to undermine the mindset whereby you attempt to implement one continuous motion.. that mindset will caryy you much better