Rotary, active vs. passive - Page 3

uh oh... have we forgotten something?

Since we seem to be talking about the biomechanical frame of reference, lets not forget there are different types of femural movements which take place in skiing... not all are rotational, but all are used in various actions transmitted to the skis...

How about circumduction? Most movements made in skiing are of this type, not pure rotation. A true rotation of the femur would be along a single axis, not one such as an edging movement would make.

The edging movement, as most do it, starts from a slightly flexed hip joint. If that femur is then tipped inward to effect an edge, that is a circumduction movement, not a rotational one. Same with any twisting of the leg, provided the hip joint is flexed.

If the people who are experts in physiology decided that there was a difference between rotation and circumduction, there must have been a reason?

PMTS does acknowledge that the skis can be redirected on the snow. The issue is how. The passive/active distinction misses the mark a bit. The use of "secondary" involves movements of the upper body that support the psrimary movements, eg. counteraction.

How about a different term for passive: innate : meaning unconditioned or unlearned. The opposite is can be either conditioned or learned.

Using those two terms:

PMTS uses rotary movements to redirect the skis that are innate to the primary movements.

PMTS does not use rotary movements to redirect the skis that are learned independently of the primary movements.

How does that grab you?

I had the chance to watch a never ever class with someone that claimed to know a bit about PMTS. I don't know who it was (just happened upon this at a destination resort which will remain nameless) or if he was just using the terms and explaining that "PMTS and direct to parallel teaches people how to ski and bypass the wedge or snowplow". It may not be a fair judgment. It was a group of 10 out of shape, middle aged people, Ill fitting gear (clearly boots too big and skis up to their foreheads) but they wanted to go ski. Getting the group to stand up and not fall on their butts was about as far as they got. As they left, I heard one mutter that "that was a waste of time. We didn't even get to slide down the hill, we still can't stop and we didn't get to ride the chair! We could have done that ourselves"

I suspect a motivated somewhat athletic group might have fared better. A smaller group probably would have been more successful as well. But the reality of most resort policies are that the never ever classes will go out with large groups, less experienced instructors and guess what, the guests are often out of shape weekend warriors.

Give me these conditions and I'll teach some active rotary (gently move those feet to a wedge) use some steering to get the feet turning. Try to turn from the femurs not from the upper body. and I can usually get a group skiing. Maybe not making arc'd turns but in 2 hours I can have the majority of the group riding the chair and exploring at least the beginner area with a smile on their face, feeling like they have some control of their speed and direction.

I'd say that is success for most guests..


DC

Was this someone a PMTS accredited coach? If not the above is totally irrelevant.

Nice VSP!!! I have gotten some grief before when mentioning circumduction. Truth is circumduction is a "blending" of movements in three planes simultaneously. Ab/adduction, flexion/extension, and rotation. this is why the hip/leg muscles wear so many hats and manage to perform movement in multiple planes at the same time. Also speaks to why the muscle exert their motive force in different planes as the angle of the femur in the hip socket changes. It is not an either or, but a complex symphony that can change from movement in any given plane to any other by a simple change in intramuscluature recruitment. We don't change to different muscles, we change from within a given muscle how hard it pulls.

Every turn I make involves circumduction. Different turn shapes and or types of turns simply require different intra/intermusculature recruitment in the hip/leg joint. We don't have time to think about this, our intent drives this choreography, supported by the movements we have already put into the body. Those are the movements we get out of the body. These are the movements available to us to execute our technique. Our sport specific movement skills.

To me this is why identifying weaknesses and working on the movements needed in isolation can be so productive as we integrate this new movement skill back into our overall skiing.

Good post!

There are movements that we make with our body that apply rotational torque on our feet both ways.

From a square stance
Movements used in skiing that apply rotational torque on our feet into the turn are:
- rotating our upper body into the turn (upper body rotation, antisipation)
- rotating our hips into the turn (hip rotation)
- rotating our femurs in our hipp sockets into the turn (pointing of knees)

Movements used in skiing that apply rotational torque on our feet towards the outside of the turn are:
- rotating our upper body towards the outside of the turn (counter/counteraction)
- rotating our hips towards the outside of the turn (counter/counteraction)

Movements used in skiing that do not apply rotational torque on our feet eather way of the turn are:
- tipping
- moving our hips sideways (angulation/counterbalance)
- banking

By combining tipping (neutral), counter (rotate out) and knee pointing (rotate in) we can adjust the torque and try to keep it to a minimum. PSIA manual says that depending on snow conditions we need to vary the ammount of rotation and that sounds like a good consept. In powder we need more rotation than on flat easy gromers or when carving.

Got it:

Rotary movements are bodily movements that are either intrinisic to the primary movements or extrinsic to the primary movements.

Intrinsic means they are inherent in the primary movements.

Extrinsic means they are not; they must be added.

There are matters of degree, but any turn requires the skis being on edge, which requires some amount of ab/adduction. This along with flexing and extending the legs and the skis turning farther across the hill than the upper body makes up circumduction.

Pivot slips without flexion and extension would be a case of hip/leg movements that don't utilize circumduction.

Even tipping the foot has an element of circumduction in it as foot eversion is a multiplanar movement. Which is why gait mechanics have the pelvis rotating around the stance leg to counteract the rotation away from the direction of travel. Particularly important in skiing.

Could you expand a little....

RicB- "Pivot slips without flexion and extension would be a case of hip/leg movements that don't utilize circumduction."

I understand what you are alluding to here, but I disagree with your premise that a pivot slip can be done without circumduction.

As the legs have to be flexed in order to manage the edge angles, (even without any flexion or extension movements), just that the hip joint/legs are flexed automatically involve circumduction during the braquage movement.
For the legs to pivot without any flex at the hip joint would either result in an uncontrollable edge(limiting success of the exercise) or if the hip joint is flexed, and a pure pivot of the femur occurs, you will not obtain the result of a pivot slip.

RicB- "Even tipping the foot has an element of circumduction in it as foot eversion is a multiplanar movement."

You can tip the foot both everted and inverted while sitting in a chair with the hip joint flexed, and without any circumductive movement of the femur. I will stipulate that the range of movement is increased as circumduction occurs, but it is not limited to that movement.

You are either using the primary movements to redirect the skis (intrinsic) or you are adding other movements to redirect the skis(extrinsic).

There is not much more to be said about it.

What that definition does, is say that all outcomes are not created equal.

Turning the feet is different when done the PMTS way than is done other ways. For one thing, there is a different tension set up within the body when you brush a carve than there is when you just pivot the legs.

Yes, the outcomes may be the same, but it can be more difficult to balance when you first use the hips to pivot the legs to turn the feet. This pivotting is an extrinsic movement.

The rotation that PMTS uses is set up with movements that are intended to keep you in balance. Classical turning of the feet can make it very difficult for the learning skier to remain balanced -- these skiers need to learn other movements to compensate for the effects of the extrinsic pivotting action. And what often occurs is a death grip like tension as this new sensation is experienced.

PMTS skiers do not succumb to this problem -- the rotation is built right into the movements they use from day one. It is naturally part of their movements.

At least that is how I see it.

Neither. What are the muscles doing?

PMTS has no intended, direct muscle activity to rotate the leg.
-Do the legs rotate?...Yes.
-Was the rotation intentionally caused by muscular effort to rotate the legs or steer the skis?...No.
-What muscular effort is used in PMTS skiing?...Tipping the skis on edge and balancing, plus flexing the legs.

Maybe maybe not. To me, movement in two planes does not constitute circumduction.


Yes we may leave the hip joint static, but the ankle joints can move in circumduction by themselves. In a ski boot the movement is restricted enough that we have to recruit femur movement to accomplish continued tipping, which while skiing, does require circumduction to happen.

This seems to be the main premise of PMTS. I have no problem with this. It is only when PMTS starts talking about brushed carves that they loose me with their explanations. By definition to me torque applied to a ski to shorten the turn shape is torque applied around an axis, which to my way of thinking is 1: not passive, and 2: steering. Whether a person is “tricked” into doing it or not.

SoftSnowGuy-

quote-"-What muscular effort is used in PMTS skiing?...Tipping the skis on edge and balancing, plus flexing the legs."


... and if you are not on super short, super shaped skis???

I hear what you're saying Bud, but this "Tomaaaato, Tomooooto" argument is one I don't buy into. Its an oversimplification. You're trying to say that two different explanations are being used for the same movements. I don't see it that way. The outcomes may or may not be the same, but the fundamental movements being exerted by the skier through thought and muscular effort are not necessarily the same. You can't begin to understand the differences if you lump them together as the same thing with different names.

When you speak of the skis relationship to the bodies vertical axis, that is also an over simplification that sweeps under the rug many aspects that would influence that relationship. But that sounds closer to being about what the bones and muscles are doing relative to each other..and has little to do with what the skis are doing on the snow.
I'm not sure that is the case. Yes definitely that is the case for their BPST, but that BPST is NOT the same as their brushed carve. Two separate concepts, though there may be some overlap in real world use. A PMTS brushed carve is carving with the edge angle reduced such that the ski does not carve a clean and perfect arc in the snow. It is not specified whether the tail is displacing more than the tip, which would cause the ski to pivot on the snow, but by your definition above, this may or may not indicate what the feet are doing relative to the bodies vertical axis, which is more of a relationship between the body parts.

Precision is needed in these conversations and debates to reach any kind of educated conclusion. If you over-simplify you will just go back to whatever dogmatic rock you crawled out from under. (that was meant for everybody)

Tell me RicB,
Maybe a little off topic, but do you see a distinction between using the twisting motion of your boot to drag your ski tips to the left and applying just enough rotary force to make those front edges catch the snow more than the rear ones so that the snow can apply the rotary force needed to pull the ski tips to the left?

I really think this is mainly a failure of language. I don't think Harald would deny, if you put the question to him carefully, that leg rotation caused by tipping is one of the turning forces in a "brushed carve". BigE pointed out p143 of "The Essential of Skiing" which talks about controlling this rotation through counter-acting movements as essential for high level skiing.

But rotation/circumduction has no role in PMTS ski instruction, because there is no reason for the skier to think about it when skiing. The movements needed to produced brushed turns differ from those used to produce a carved turn only in their intensity and timing. There's no trick, except that the same set of movements can produce a whole range of different outcomes. Saying the rotation is "passive" is a reasonable way to tell the curious student that he shouldn't think about it when skiing or try to work on it, isolate it, or improve it. If you can think of a better form of language, go right ahead and suggest it.

I have been trying to explain how counter affects rotation to the foot in the other direction, towards the outside. This way you can adjust the ammount of rotation by counteracting.

There were a few major ideas in the book.

1) Never do anything but carve.

2) The fall line is where you gain the most speed....always try to stay pointing (CM that is) to where you can gain the most speed.

If you think about some of the platforms of PMTS I'm sure you can see the connections to the concepts in this book, which I think was written in the 60’s.

Carving vs skidding (they were not up to flat may be faster yet....just that you might skid from a flat ski if you try to turn)

I don't recall any mention of vertical motion/up unweighting. If you think about it.....it wouldn't fit the bill. In order to get your CM down the hill the fastest way, you would have to move across, not up, by flexing your legs at transition.

This should sound and look awful familiar if you have been to the Bullitt Proof thread.

Here is my only issue beyond what I consider to be correct technique above.....

I recall a post by Mikewil that told a story of Shawn Smith (US D team) and Warren Witherall (the books author) skiing together at (I think) Snowbird. They came to a long, steep narrow chute and Shawn commented to Warren, “We’d like to see your very best carves here”.

To which Warren replied, “There is a time and a place for everything.”

I wonder if HH agrees

In some instances, like the one I mentioned in my last post, arcing and "brushing" will not suffice. Where the terrain is VERY steep and narrow and there isn't room for anything but a hop or retraction turn there clearly becomes a need for ACTIVE LEG STEERING. Unless you plan on skiing it at 60 plus mph.

If so.....good luck.

It is true that you cannot carve on such terrain. No-one who has ever skied on anything even slightly steep believes that you can. In fact, as you say, you can't ski with your skis on the snow, you have to hop or retract the skis. Harald doesn't touch on this at all in PMTS books. Eric DesLauriers does talk about it in "Ski the whole Mountain". He suggests it is possible to make a full or partial hop turn using what are essentially PMTS movements. You can certainly make retraction turns the same way - you only have to look at Max in the other thread.

I'm not sufficiently confident in my own skiing to try this on the terrain its intended for, but I have tried it on shallow slopes and it does work. Is there are any reason to believe that active steering from primary movements has any more range or power than "passive" steering from tipping movements? Since we're apparently talking about the same circumduction movements in both cases, I'm not sure there is.

Sure, I call that skill blending. Blending in more steering torque to achieve a smaller turn radius than the pressured ski's geometry will give you. To say you get many different outcomes from the same movements just doesn't sit well with me. Something more than intensity and timing changes, otherwise the ski's geometry will still rule. Increasing the intensity until you break loose the ski's edge and the ski/snow interaction is in my book pure and simple steering. I don't care that you choose to describe it however you want, just don't expect me to agree.

I see distinctions and nuances all over the place. I like to work and move with the energy and utilize the ski to it's max and then supply whatever else may be needed for the given situation. So yes moving with the ski and letting the tip lead the tail is always the best way to go IMHO. Now if you are incinuating that over pressuring the tip like reefing on my boot's tounge is good thing then I will disagree. I like to see and feel the balance in the middle to a little forward under my foot. Actively centered and balanced. Not heavy handed or forced, but in harmony with the energy, adding just enough active energy of my own to realize control and intended direction and outcome. Developing that touch and feel for what the skis are doing and understanding what needs to be done. Not in some predetermined way but in the moment, and in anticipation of the good things to come.

What he said...

When you "blend in more steering torque", do you make the tips slide more into the inside of the turn (that's how I'm reading your description), or just have them slide less to the outside of the turn?

The first point to consider is that Warren is not a PMTS trained skier so he probably didn't know how a PMTS skier like HH would apply PMTS in this situation (Has anyone seen WW ski? I'm wondering how good he is). Second, I'm guessing that Harald's skiing is very different from Shawn Smith's skiing so I'm sure Harald would have a very different approach in that situation. I'd bet that HH has skied every chute at Snowbird. I've skied with HH down some very steep runs. While none were chutes with rocks on either side we did do a run where we created a faux chute by agreeing we couldn't go outside of a path that was a bit larger than a ski length. He was freaking amazing to watch and he didn't do any hop turns. I don't know how the heck he does it, but man, its amazing to see. When he says he's going to get a ski upside down and use the ski all the way around he means it.

Just a quick edit: I'm not suggesting that WW or SS are anything but great skiers (how would I know, that's why I asked about WW). My apologies if anyone takes it differently.