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# What's wrong with rotation? - Page 2

Quote:
Originally Posted by Coach Z

Coming in late to this topic but the way I see it is if I'm on a 18m ski and just apply edge and pressure my complete 180 degree turn will take me approx 120 feet down the hill. We all have to apply some rotary force to shorten our turns from that.

You could tip the skis up onto their edges to shorten the radius of the turn cut in the snow.

+1
So what do you do when you have bent the ski as much as you can and still want a smaller radius turn?
Avoid edge lock
Quote:
Originally Posted by borntoski683

Avoid edge lock

So that tail skid rotation AKA: over-steering can occur?

If you have to turn tighter than a fully bent 10-11 m ski will on its own then maybe you should be pivoting between turns instead

Quote:
Originally Posted by justanotherskipro

So what do you do when you have bent the ski as much as you can and still want a smaller radius turn?

Maybe your answer is "you can't always get what you want but if you try some times you just may find that get what you need"

(perhaps a good mantra for those who's intentions are to manipulate the effects of gravity)

... and, while what you want may be a tighter radius turn, what you really need (for whatever requires such a tight radius turn) may be found in the transition.

If you put all your weight on one ski, you can bend it a little bit more.  If you put all of your weight on the front half of one ski you can bend it even further.   If you need to bend it more than that I suggest a stivot.  Rotating a flat ski will only take you on a wider turn.

That's right ghost.

I was only addressing the statement earlier that on an 18m ski the only way to make a turn tighter then 120 feet was to twist the legs. That's simply not true. There are all kinds of ways to get a tighter turn without twisting the legs. Tip more, bend more, smear more.... The turn will tighten substantially without one iota of leg twisting.

As you pointed out rightly, in order to twist the skis to steer more the ski has to be pretty flat which reduces reactionary forces and widens the turn radius if anything, at extremely slow speeds twisting a flat ski can work. At even moderate speeds that approach will not tighten the turn, it will require flat skis which widens the turn.

There is still a time for a stivot or pivot entry as rich suggested. And definitely that can get a tighter line at higher dynamics. However note that pivoting and stivoting are not the same thing as steering. Nonetheless a pivot entry definitely can involve some rotary, and is sometimes useful at the expense of high c engagement, which is also useful for speed control. It's a compromise. Need the tighter line or need speed control? Is your reason for a tighter line to get speed control? Maybe you'd be better getting high c engagement? Or maybe not. It depends. But I say most of us will be better off with high c engagement most of the time.

There is nothing inherently wrong with rotation, or counter-rotation, or leg rotation, or any other rotary mechanism, or with no rotation or rotary  either. They are all legitimate and important movements in skiing, when tied to the correct outcome or intent--and they are all wrong when tied to the wrong outcome or intent. They all represent critically important skills for the complete and versatile skier to explore and master, to learn to use when and as much as appropriate for any given situation, and to learn to regulate and "switch off" when appropriate as well.

The problem with many of the discussions these days at EpicSki and elsewhere lies in turning a movement--virtually any movement--into a "must do" or "must not do" thing, an end in itself rather than a tool to be acquired, managed, and exploited with skill, panache, and possibly restraint.

Rotation (that is, "upper body rotation," or any of its variants, all of which involve a two-part sequence of turning one part of the body against another part that is in turn blocked from "counter-rotating" by the earth--through an edgeset or some other resistance--and then transferring that rotational or angular momentum to the ski or skis by slowing or stopping the rotation of the first part, exploiting Newton's Law of Conservation of [Angular] Momentum) has effects. All movements on skis have effects. The question is not whether the movement is "right or wrong," but whether or not its effects are what you want in any given situation.

Simply put, rotation imparts a twisting impulse to the ski or skis, and generates rotational (angular) momentum to the whole ski/skier system. In other words, it twists the skis, and adds a degree of "spin" to the skier. It's a powerful move, and in classical ski techniques (the French called it "projection circulaire") it was an effective way to throw the skis sideways and twist them into a skid to start a new turn. For today's freestylers throwing aerial spins, obviously, it's a fundamental tool. (Conversely, it's worth noting that the same principle can also reduce twisting or skidding or turning of the skis when used "in reverse" to transfer momentum from the skis to the upper body. Think of a freestyler who rotates his body after landing from a spin, in order to keep his skis running straight; we often see the same principle, albeit with more subtlety, in many alpine turns to help stop a skid or end a turn.) Typically, the ski twist that rotation creates turns the skis to an angle from their direction of travel, causing skidding. It's a mistake, then, if you're trying to avoid skidding, but a helpful tool if you want to twist your skis into a skid--for braking, or recovery, or any other reason.

Rotation does not always cause skidding, and it can even help skis hold better when used in a highly refined way. A little skillful rotation in the transition can simplify and reduce the workload of the skis through the turn, allowing them to devote all their energy to controlling the line. How so? Consider that most turns involve a direction change in both linear motion (moving along a curving path) and angular motion (turning about an axis to face a new direction). Subtle upper body rotation prior to the initiation of a turn can impart the needed angular momentum to the ski/skier system prior to the turn, leaving the skis to manage only the linear motion (that is, to grip, carve, and follow the curving path) through the turn itself. If this is hard to understand, don't worry--it's such a subtle move that probably only matters to top-level racing and, even there, it's not something most top skiers "think about" or even understand themselves. It explains, though, one reason why World Cup racers very often do show a little rotation in their transitions, typically seen as hand and arm movements (note how often racers' outside hands lead their inside hands through turns--a basic "error" to anyone who thinks that all rotation is inherently wrong). Of course, there are other reasons as well, including sometimes the need to twist the skis sideways (as in a "stivot") or to hit the brakes. There are many kinds of turns, many different and constantly changing needs and intents in skiing, and many different sensations to be sought. The best skiers are limited only by their creativity and imagination--not by the dogma of what is "right or wrong."

---

In movement analysis, rotation is most often identified by observing the alignment of the various body parts throughout a turn, and by observing "what turns first"--upper body, including any or all of head, shoulders, arms, hips, or torso, or lower body--skis and legs. If the upper body starts turning (rotating) to the new direction before the skis do, it's a good sign you're observing the first part of the "one-two" sequence of classic rotation. If the outside hand, arm, shoulder, and/or hip leads its inside counterpart through the turn, it's a very good indicator that some sort of upper body rotation has occurred. With this in mind, what do you observe in the following video of Ted Ligety? What typically turns first? Which hand typically leads through most turns?

There is clearly rotation going on here. Is Ligety wrong? Is he making fundamental mistakes? Does he suck? Or is he the current World Champion (GS)?

Best regards,

Bob Barnes

PS--here's another interesting perspective on Ted Ligety skiing. Unfortunately, I haven't been able to find this on YouTube, so I cannot embed it. You'll have to click on the link:

Ted Ligety in powder video clip

Here's a screen shot from this clip (about 6 seconds in):

Quote:
Originally Posted by Bob Barnes

There is nothing inherently wrong with rotation, or counter-rotation, or leg rotation, or any other rotary mechanism, or with no rotation or rotary  either. They are all legitimate and important movements in skiing, when tied to the correct outcome or intent--and they are all wrong when tied to the wrong outcome or intent. They all represent critically important skills for the complete and versatile skier to explore and master, to learn to use when and as much as appropriate for any given situation, and to learn to regulate and "switch off" when appropriate as well.

The problem with many of the discussions these days at EpicSki and elsewhere lies in turning a movement--virtually any movement--into a "must do" or "must not do" thing, an end in itself rather than a tool to be acquired, managed, and exploited with skill, panache, and possibly restraint.

Rotation (that is, "upper body rotation," or any of its variants, all of which involve a two-part sequence of turning one part of the body against another part that is in turn blocked from "counter-rotating" by the earth--through an edgeset or some other resistance--and then transferring that rotational or angular momentum to the ski or skis by slowing or stopping the rotation of the first part, exploiting Newton's Law of Conservation of [Angular] Momentum) has effects. All movements on skis have effects. The question is not whether the movement is "right or wrong," but whether or not its effects are what you want in any given situation.

Simply put, rotation imparts a twisting impulse to the ski or skis, and generates rotational (angular) momentum to the whole ski/skier system. In other words, it twists the skis, and adds a degree of "spin" to the skier. It's a powerful move, and in classical ski techniques (the French called it "projection circulaire") it was an effective way to throw the skis sideways and twist them into a skid to start a new turn. For today's freestylers throwing aerial spins, obviously, it's a fundamental tool. (Conversely, it's worth noting that the same principle can also reduce twisting or skidding or turning of the skis when used "in reverse" to transfer momentum from the skis to the upper body. Think of a freestyler who rotates his body after landing from a spin, in order to keep his skis running straight; we often see the same principle, albeit with more subtlety, in many alpine turns to help stop a skid or end a turn.) Typically, the ski twist that rotation creates turns the skis to an angle from their direction of travel, causing skidding. It's a mistake, then, if you're trying to avoid skidding, but a helpful tool if you want to twist your skis into a skid--for braking, or recovery, or any other reason.

Rotation does not always cause skidding, and it can even help skis hold better when used in a highly refined way. A little skillful rotation in the transition can simplify and reduce the workload of the skis through the turn, allowing them to devote all their energy to controlling the line. How so? Consider that most turns involve a direction change in both linear motion (moving along a curving path) and angular motion (turning about an axis to face a new direction). Subtle upper body rotation prior to the initiation of a turn can impart the needed angular momentum to the ski/skier system prior to the turn, leaving the skis to manage only the linear motion (that is, to grip, carve, and follow the curving path) through the turn itself. If this is hard to understand, don't worry--it's such a subtle move that probably only matters to top-level racing and, even there, it's not something most top skiers "think about" or even understand themselves. It explains, though, one reason why World Cup racers very often do show a little rotation in their transitions, typically seen as hand and arm movements (note how often racers' outside hands lead their inside hands through turns--a basic "error" to anyone who thinks that all rotation is inherently wrong). Of course, there are other reasons as well, including sometimes the need to twist the skis sideways (as in a "stivot") or to hit the brakes. There are many kinds of turns, many different and constantly changing needs and intents in skiing, and many different sensations to be sought. The best skiers are limited only by their creativity and imagination--not by the dogma of what is "right or wrong."

---

In movement analysis, rotation is most often identified by observing the alignment of the various body parts throughout a turn, and by observing "what turns first"--upper body, including any or all of head, shoulders, arms, hips, or torso, or lower body--skis and legs. If the upper body starts turning (rotating) to the new direction before the skis do, it's a good sign you're observing the first part of the "one-two" sequence of classic rotation. If the outside hand, arm, shoulder, and/or hip leads its inside counterpart through the turn, it's a very good indicator that some sort of upper body rotation has occurred. With this in mind, what do you observe in the following video of Ted Ligety? What typically turns first? Which hand typically leads through most turns?

There is clearly rotation going on here. Is Ligety wrong? Is he making fundamental mistakes? Does he suck? Or is he the current World Champion (GS)?

Best regards,

Bob Barnes

PS--here's another interesting perspective on Ted Ligety skiing. Unfortunately, I haven't been able to find this on YouTube, so I cannot embed it. You'll have to click on the link:

Ted Ligety in powder video clip

Here's a screen shot from this clip (about 6 seconds in):

"Make the mold...break the mold."   Learning most arts there are fundamentals to be mastered.   The fundamentals being the basic rules you follow to succeed.    The Chinese Yin/Yang symbol    denotes by the small opposite colored dot in the center of each side of the symbol that there are exceptions to every rule.  There is a difference between a WC skier using upper body  rotation as a finesse move and an intermediate skier using rotation as a primary turning force.    Exceptional movements are no substitute for sound fundamentals.   YM

What dogma are you perceiving BB?

By the way, in the above videos I see Ted carving, not twisting the skis.  Is the body making lots of rotational and counter rotational movements?  YES!  Is he twisting his skis....NO!

In the powder skiing he is also basically carving his skis the same way...  we won't look too closely at the couple of stems in there.  just sayin'

Yogaman and BTS--no argument with either one of you, and no contradiction to anything I wrote in my previous post. BTS--you know what the dogma is. For one thing, it's inherent in the title of this thread.

Best regards,

Bob

heh heh  fair enough..

The title of the thread was copied from the title of the Ski Canada article, no dogma intended by me (don't know about Ski Canada though).  Just say'n.

Understood, Ghost--and I almost mentioned that in my last post. It's a good topic for discussion, even if (especially if?) it leads to some good myth-busting! Thanks!

Best regards,

Bob

Its important to point out that the  meat of that article was about upper body rotation, not lower body rotation.  The good ol' shoulder turn....which STILL in my view has an occasional usefulness, though is unfortunately used by many mid level skiers as a fundamental.  I think most people will universally agree with the article in general principle.

Quote:
Originally Posted by Bob Barnes
.....

PS--here's another interesting perspective on Ted Ligety skiing. Unfortunately, I haven't been able to find this on YouTube, so I cannot embed it. You'll have to click on the link:

Ted Ligety in powder video clip

Here's a screen shot from this clip (about 6 seconds in):

That video camera keeps itself oriented downhill as Ted's head turns left and right.

How does the camera know which way to point?  Does anyone know?  It must be locked onto something, but there's nothing in the image that doesn't change position.

This is a great improvement over the camera that keeps itself always pointing forward relative to the helmet.

That frame of reference makes it difficult for viewers to perceive the radius of the turns.

This is better.

Has to be some sort of multi-axis powered gimbal mount, LiquidFeet. They really are amazing these days! I would like to see the rig from another camera. Ligety has done a great job for some time now filming from unusual, creative, and high-tech perspectives. Thanks, Ted!

Here's one.

Best regards,

Bob

Quote:
Originally Posted by Bob Barnes

For one thing, it's inherent in the title of this thread.

Best regards,

Bob

There's a topic for another thread...  "when is upper body rotation wrong"?   As coaches/instructors we need to discern when something is helping and when it is hurting.   Certainly with high level athletes, discovering what is working or not  is a team effort between the coach(es)  and the athlete.   YM

When is it wrong? That is the question, isn't it. I suggest, though, that rather than approaching it from a right/wrong perspective, it would make sense simply to explore the cause and effect relationships of these, and other, movements. It's never wrong if its effects are what you want. (Although perhaps there are reasons, sometimes, to question even "what you want." As Steve Jobs famously said, "it's not the customers' job to know what they want...." Often students of skiing--like almost anything else--don't even know that what they really want exists, until you show it to them! But that's another story.... Rotation definitely "solves some problems," but a better tactic is often to eliminate the problems it solves in the first place. Like many things we often see as "errors," often rotation is really just a solution to the wrong problem.)

In any case, there are certainly many reasons why upper body rotation is often undesirable. It causes (possibly unwanted) excessive skidding. It puts the body into positions that can be weaker and that can limit important movement options such as hip angulation--and necessitate substitute movements that may be less effective, weaker, or dangerous--such as knee angulation. It is "slow," in that It typically introduces angular (rotational) momentum, or "spin," which must then be stopped in one direction before you can turn the other direction, and it relies on the establishment of a solid edgeset "platform" before we can start the next turn. It is a powerful way to twist skis, when you need to twist skis, but it tends to be unrefined and imprecise, hard to regulate to the exact amount needed. Turns initiated with upper body rotation, as in the old "Arlberg Technique," were prone to either "under-initiation" (too little rotation to start, causing the skidded turn to "die" prematurely, often needing another rotational effort to continue the turn to completion), or "over-initiation" (too much rotation to start, perhaps causing the turn to skid out of control and spin out, and requiring additional movements and effort to stop the turn). Rotation often (but not necessarily) leads to pronounced "banking," low edge angle, and difficulty maintaining balance on the outside ski. It is often the culprit that causes an unintentional "abstem"--a skidding out of the tail of the downhill ski a the end of the turn, as the skier seeks to re-establish grip and create the solid "platform" from which his next rotation initiation will start. And for sure, if your goal is the cleanest-possible carved turn, there is no reason to twist the skis off-line at all--using rotation, counter-rotation, or anything else. Although as I described earlier, even here, a small amount of highly-refined rotation may, at the highest possible levels, add just another small degree of performance to the turn (by eliminating the need for the skis to "turn" or rotate the skier from one direction to another during the turn).

Rotation, along with counter-rotation, blocking (typically pole plant), and independent leg rotation, is a "rotary mechanism." It is a way to manage torque in skiing--to turn the skis, or stop them from turning, to turn the body, or to stop the body from turning. Rotary mechanisms are both how we throw ourselves into a spin and how we stop a spin. They are both how we turn our skis when we want to turn them, and how we prevent them from turning when we want them to remain online (as in a pure-carved turn transition). Rotary mechanisms live among the fundamental skills that we must develop, and that continue to develop throughout our skiing career. They are not an imperative. No matter what many people seem to believe, there is no skiing or teaching "system" that I'm aware of that mandates that you "should" twist your skis to start turns. It is an option, a possibility, a point on a broad spectrum, and it is the mastery of that entire spectrum that marks all truly great skiers.

Rotation is also highly intuitive. Typical new skiers tend to want to fight their skis' natural tendency to glide--especially down the hill--and intuitively seek ways to twist their skis sideways. Upper body rotation is surely the most intuitive way to do that, and left unabated, it does lead to a number of bad habits. On the other hand, the rotation of the legs beneath a stable pelvis and upper body--either "active" (muscularly driven) or "passive" (allowing other forces, including from the skis, to turn the legs) is a very important movement in skiing and, unlike upper body rotation, it tends not to be intuitive at all. It's not a difficult movement, but there are few calls for it in "everyday life," so for most people, it is essentially a "new movement" that they must learn. For these reasons, modern teaching tends to spend a lot of time trying to eliminate the intuitive upper body rotation and develop the critical leg rotation that can often replace it.

So I would readily admit that, although I reject all notions that rotation is inherently a bad thing, it is certainly a bad habit. Any movement made without direct connection to a purpose--as in simply because it's a habit--is one worth exploring, and worth looking into its alternatives. Rotation causes at least as many problems as it solves, but without it, there are many problems that would be unsolvable. Although I've provided some clear examples of upper body rotation at the highest levels of skiing, in Ted Ligety, I would also assert that it is not what I would call a "default" movement in modern skiing. In other words, I spend much more time teaching people not to do it than to do it (except perhaps in a freestyle situation). But still, any "good" skier who is not a master of rotation will be a better skier once it's mastered.

Best regards,

Bob

Quote:
Originally Posted by Bob Barnes

When is it wrong?

Best regards,

Bob

When it results in pain or embarrassment.

fom

Quote:
Originally Posted by Rich666

Quote:
Originally Posted by razie

so by rotation you mean square, which is not hip - but i don't know if we should say he's square in SL. square means staying square to the skis as the skis turn... in SL his body is "quiet", i.e. not exagerating either rotation or counter-rotation. so he's square for a msec, even rotating for a msec but counter-acting for the most part.

GS requires different tactics.

Anyways, the issue with Rotation in general is that you're out of balance, as in dynamic balance. That's all. The rest is like those little shiny pieces of glass, you know, distracting....

Cheers,
Raz

cheers

I think you are right about that. While I am thinking in terms of squaring up just a few angles within a 0.25 second transition, Marcel is prob not a good example as well. I just couldn't resist using his anyway.

I think this may be your photo below shared in another thread of which, for me, offers an excellent example of squaring up between turns and, more particularly, the lower half.

ph... (very) long flight...

I am always right and yes, he is better than Marcel, true enough..

However, for expert like those , it is mostly a matter of how much the skis come out off the fall line in a given turn

Not to forget tactics, like BB notes above... anything might be ok, depending on what you need.

Razie--one thing, if you have not considered it, is to recognize that when the hips are deeply flexed, as in the image you posted (reproduced below), range of rotation in the hip sockets diminishes severely (as it also does when the hips are greatly extended). It is common to see a deeply flexed skier like this one with a fairly square lower body (that is, skis and hips facing essentially the same direction), even if he might have remained more "countered" if he were less flexed. I'm not suggesting that this alone explains his more square position in this image, but I suspect it contributes strongly to it. I caution against "trying" to square up intentionally between turns based on this image.

You can demonstrate this effect just standing on your living room floor. Start in a naturally flexed athletic skiing stance, and rotate both femurs in their hip sockets one direction or another, creating as much counter as you can. (Your feet should be pointing well off to the side from where your pelvis and upper body are facing.) Now slowly flex your knees and hips and get lower and lower, without moving your feet. Unless your anatomy is very unusual, you will find that your pelvis rotates and becomes increasingly square to your skis as you flex lower and lower, even if you try to prevent it. You may be able to maintain counter between your shoulders and your skis by twisting your spine as your pelvis rotates (as the skier in your image does), but you will clearly see the range of rotation in your hip sockets decrease with deep flexion. Maximizing that range is one of the functions of the functional, athletic stance in skiing--not too straight, not too flexed, just right (at least as a starting point).

Best regards,

Bob

And where does the movement for a pivot or smear come from?

Same place the femur rotating in the hip socket
Quote:
Originally Posted by Coach Z

And where does the movement for a pivot or smear come from?

Same place the femur rotating in the hip socket

you can cause a skid/smear in many ways... only one of them is a purposeful rotational movement (i.e. twisting the feet).

ignorant question: is a pivoting movement centered in the upper body? does it come from the upper body?

I was just thinking about one of the differences between edging and pivoting and edging is an action of the lower legs, regardless of the upper body (even decoupled by flexing the knees/hips), but when you try to pivot i.e. twist the feet, isn't that centered in the upper body? i.e. you can't twist the feet without an upper body to rotate against?

Edited by razie - 10/4/15 at 10:57pm

In independent leg steering, the rotation comes from the femurs rotating in the hip sockets.  The upper body (including the hips) resists this rotational force.  When lower-level skiers turn, they usually lack this separation and the upper body (parts or all) starts the rotation of the legs, usually tipping them uphill and out of balance, with a tail skid.

Edited by mike_m - 10/5/15 at 7:10am
Huh? Why do you say there is only one purposeful rotational movement?
Seems thoretically restrictive to me. ILS gets ignored in that statement.

I wonder about the rest of that statement and am hoping for a bit more clarification Razie. Especially in the stuff about the hands and feet where we see three dimensional movements without the need for the core to be involved. Granted the muscles in the upper leg / arms are involved to a minor extent and their proximal attachment point is the torso but it seems like a leap to suggest twisting the feet originates in the torso.
Quote:
Originally Posted by razie

I was just thinking about one of the differences between edging and pivoting and edging is an action of the lower legs, regardless of the upper body (even decoupled by flexing the knees/hips), but when you try to pivot i.e. twist the feet, isn't that centered in the upper body? i.e. you can't twist the feet without an upper body to rotate against?

Now if you are floating around in outer space, in freefall in vacuum or standing on one leg on a frictionless device then twisting one leg in the femur, this will case the rest of body to rotate in the opposite direction. But not by much because of the mass difference between the leg and the rest of the body. And I guess it should be the same even if you are rotating both legs on frictionless devices, the rest of the body will rotate in the opposite  direction. However the impact of that opposed rotation during skiing is rather slim...

correct smear.

The reason an upper body shoulder turn works so well, and it does actually work well at creating angular momentum (with unintended consequences), is because the foot is anchored to the snow and you have something to push against while turning the upper body into the turn.  This create angular momentum which eventually causes the ski to rotate also.  Its like being able to push off a sprinter's block, but in an angular way.

This is one reason why so many low to mid level skiers...and even plenty of higher level skiers I have seen, intuitively just start doing it.  Its just very very easy to get angular momentum this way...  MUCH easier then trying to somehow keep the upper body stable while twisting the legs underneath it.  In some circumstances, such as the powder Ted was skiing above in BB's post the negative consequences are almost entirely eliminated and its not really such a devastating move...actually can be useful.  I agree with what BB said earlier...there is no such thing as bad movements (mostly), but bad habits yes! If a skier becomes reliant on doing the angular sprinters block thing to create angular momentum for the turn, in addition to the way it causes the skis to flatten, yada yada yada, there is a much more insidious problem.

The skier unwittingly avoids learning other important movement patterns that are needed to create angular momentum a better way.  When I see a high level skier...and I gave a story earlier of myself, that has even a slight shoulder turn to start the turn.  That shows the skier is using that trick due to a deficiency in turn initing.  Might be slight, might be major, but if it becomes a chronic and habitual shoulder turn, then the skier is lazy with the lower body for initing turns.  Most likely deficient tipping skills.  Some here will argue the case for deficient lower body rotation (more on that in a minute).

Either way, whether you come from the twist your skis to init the turn crowd or the tip your skis to start the turn crowd or the it depends, might be either one crowd, all of them universally agree, that doing one of these lower body movements is better then pushing off the uphill ski with an upper body turn as described in the article.  And skiers who do it habitually, are most likely deficient in that lower body movement work.  They may see a more immediate angular momentum result doing it that way, that is why low to mid level skiers intuitively just start doing it.  It feels natural, its easy, short gains for long term loss, but the unintended consequences later in the turn are because of having done it that way.  Sure in powder or a few situations, can definitely pull out the angular sprinters block move and it can absolutely be useful.  its like creating a bit of anticipation that wasn't held over from counter in the last turn.  But if its a habit due to deficiencies in lower body turn init movements, then the skier is headed on a path to burning in wrong muscle memory movements.

Lower body rotation is another thing.  The upper body is not anchored to anything.  In order to have this appearance of the upper body being stable....looking like its anchored, even though it isn't, is to counter act the rotational movements in some way, that is exactly the right amount so that from the frame of reference of an outside observer, or the tree at the bottom of the slope your instructor told you to ski the whole run with your chest facing that tree, or whatever..  But the point is, in order to do that, your legs turn one way and you have to physical counter act, counter rotate your upper half, whatever you want to call it..the opposite direction the legs are twisting, JUST THE RIGHT AMOUNT, so that this appearance takes place. But...make no mistake..the upper half is not anchored to anything...  As Smear described.  Pivot slips are about a million times easier when this concept is understood.

But I want to iterate again, this is not the only way to get the skis to pivot.  Simply tipping them and avoiding edge lock will also cause the skis to pivot or steer themselves, due to snow reaction forces and gravity and our state of balance on them.

Quote:
Originally Posted by justanotherskipro

Huh? Why do you say there is only one purposeful rotational movement?
Seems thoretically restrictive to me. ILS gets ignored in that statement.

I wonder about the rest of that statement and am hoping for a bit more clarification Razie. Especially in the stuff about the hands and feet where we see three dimensional movements without the need for the core to be involved. Granted the muscles in the upper leg / arms are involved to a minor extent and their proximal attachment point is the torso but it seems like a leap to suggest twisting the feet originates in the torso.

i meant - thinking action and reaction, right? we push the wall, the wall pushes back...but we push the wall by way of leverage against the floor.  if rotating the feet (willfully) is the action, what is the leverage? you can't move something without some leverage - so, from a physics stand point, what is the leverage that allows us to rotate the lower feet? it seems to me that the only thing to leverage would be the upper body's rotational status.

yes, of course, the impact would be small and often hidden, given the relative mass difference (although the skis are long meaning added leverage) and how we can easily steal some rotational impulse even from a heavily skidded turn, but just thinking straight action/reaction, i could not see another lever...

when edging, the leverage is a torque in the boot (if the knees are not simply pushed to the side) so action/reaction are both right there, in the lower leg... there is no impact to or reliance on the upper body...

cheers

p.s. i was just thinking some physics when the coach asked where dest the pivot come from and the only answer i could come up with was "the upper body" which sounded weird enough..

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