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# Isolated movements?

In a recent thread we were discussing movement classifications and the term isolated came up. Two understandings of the term were discussed and debated. Without getting back into that debate I promised I would re-post some examples of truely isolated movement as defined by the absence of other skills in these movements. I though it would be fun to see how many of these movements we could come up with. Here's my four...
• Picking a ski up off the snow doesn't involve changing the edge angle, or pivotting the ski
• Pivotting the tip of that ski we have in the air moves the tip left and right but doesn't include any pressure or changing the skis edge angle
• Tipping that ski in the air involves rolling it over along it's long axis with no pressure or pivotting involved
• Raising and lowering the tip of the ski that is still in the air changes the skis position relative to the snow without any lateral pivoting or change in edge angle.
Along with these and whatever additional movements we can think of, I also wonder just how many of these would be used while actually skiing?
Hold out your hand flat in front of you, palm down.
Apply a pure translation, i.e.  move it right, move it left, move it forward, move it backwards, move it up, move it down, all while keeping it's orientation the same.
Apply a rotation about an axis in line with your forearm, keeping it's centre of mass at the same location without letting it rotate about any other axis.
Apply a rotation about an axis perpendicular to both that axis and an axis perpendicular to the surface of your palm without letting it translate, or rotate about any other axis.

Can you do it?  I bet you can.  It may be a bit tricky for some people, because the hand being attached to the arm may force you to move you body as well and you may have trouble coordinating it just right without letting any non-called for moves if you've been drinking.  We've all learned to get our muscles to cooperate to move our hands just so.

Can you do it with your foot?  With a ski attached?  While skiing?

Apparently some people can't.
There are some who argue that tipping a lifted ski is actually used in actual skiing.

Ghost, getting the ski to only move (pivot) around one axis, or move up and down along one axis isn't hard while standing still but once in motion many skers find it more difficult. Not so much because the movement becomes harder but mentally it is outside the box so they never practice these sorts of moves.
Exploring these moves further what are some specific examples of them being used as we ski? In addition , I must say I didn't think about the hands but let's expand on hand usage for a moment. Not so much in the static drills but in everyday ski usage of the hands.

Balance.  They are moving in an unconscious attempt to try and regain balance.  Improving their balance would improve their ability to make any particular moves when skiing.

Hands are used as a part of balance.
Skipro, I may be misunderstanding your statement.  Doesn't any action require an equal and opposite reation?

Any motion of a body will require compensation by the body, once you get much past blinking.  Can you alter stance or balance without necessatateing an alteration of the forces you apply?  Wouldn't any movement of weight make you compensate in the forces to the ski that is in contact with the ground.  Dynamic balance if you will.

If you are on a snowy slope and raise one ski, you inherantly must increase the weight on the other ski.  You would increase the flex and torsion on the weighted ski, if on a slope it will want to slip without altering your edging.

Pivot the lifted ski, and you will create rotary force on the weighted ski by weight transfer and or muscular/skeletal stress depeding  on the speed the pivoting is done.

Tip the lifted ski and you must compensate for that motion on your weighted ski, you would have to alter your COM.

Raise and lowere that lifted ski and you again you will increase flex and torsion of the ski on the ground.
Your stance doesn't need to change if you assume the basic stance it would take to balance the CoM over the BoS before picking up the ski. In fact, this is a balancing drill used in boot balancing clinics all the time. If the ski pivots or gets tipped on edge as you pick up the ski, your boot isn't aligned very well. So no, stance doesn't need to change in this example beyond picking up the one ski.

No See the above drill for clarification. If the forces in play line up and pass through the CoM and the BoS no extra edge angle or pivotting of the ski is needed.

Pivoting the ski in the air doesn't mean doing so to the point that you create a pivot in the stance ski.

True a lateral displacement of the raised knee changes the location of the CoM. Although lateral balancing skills are what tipping is all about and all of these compensatory moves can be within the classification of tipping since you don't need to pivot the skis or change the foot to foot pressure, it's already on just one ski.

I can raise and lower the tip of a ski in the air without changing my balance point or adding torque to the stance ski.
JASP,

*Outcomes* in isolation is not what *skills* in isolation is about.
Edited by BigE - 9/26/09 at 8:13pm
Outcomes in isolation is exactly what this thread is about E. The classification of these outcomes by how they move the skis. Tipping in the absence of pivotting or pressure control, pivoting without adding or subtracting edge angle or pressure, pressure control without adding or subtracting pivoting, or tipping. All of these are very specific outcomes that describe what the ski is doing. What we need to do to produce that outcome is obviously involved but the topic is very much about the outcomes. I also added the question of how many of these activities we actually use in this isolated way when we are skiing instead of doing drills.

Beyond that a discussion of CSIA's methodology and how your system indentifies skills is interesting but not the topic of this thread. I know you feel passion for that but that is a subject of huge proportions and deserves a thread entirely dedicated to that.

As you said yourself, you can't think of any that occur when the ski is attached to the snow.

But, I'll play:

Retraction/extension in a straight run decreases and increases pressure without changing steering angle or edge angle. In a mogul field, it is a key component of Absorption and Extension.

Pivotting a totally flat ski will change steering angle but not direction. In a mogul field, you can pivot on the top of a mogul. You can do it In transition on a groomer to create a pivot entry.

Fore and aft balance adjustment as the ski enters and exits a turn is required to maintain centered pressure distribution, even though the edge angles are changing. Does that count?

Extending and flexing to maintain equal pressure through the turn -- applying pressure at the top and subtracting at the bottom. Even though the edge anges are changing.

During a weightless transition, Increasing edge angles pre initiation, no pivotting, no pressure change.  The ski will continue to move in the exact same direction as the CM, since there is no pressure. Once there is pressure the ski will turn.

• Picking a ski up off the snow doesn't involve changing the edge angle, or pivotting the ski

Picking a ski up will change Centre of Mass and Base of Support (I'm assuming your example is picking up the inside ski).  To re-establish BOS, you would adjust lateral balance, which could involve a change in edge angle, or if you want to maintain the established edge angle, you'll have to shift part of your body above COM outwards.  In either case, it looks like picking the ski up can't be done in isolation from other compensating or adapting movements.

If you "pre-compensate" by establishing BOS on the outside ski before lifting the inside ski, you've come closer to isolating the movement, but it's kind of an artificial isolation (even though this COM and BOS combination can occur at a certain point in a high performance turn).

• Pivotting the tip of that ski we have in the air moves the tip left and right but doesn't include any pressure or changing the skis edge angle

With the ski in the air, pivoting about the tib/fib axis should be pretty close to an isolated movement because tip movement is balanced by tail movement.  However, I can't think of a practical application of this move.  If  it becomes a javelin turn, there will be other movements that come into play.

• Tipping that ski in the air involves rolling it over along it's long axis with no pressure or pivotting involved

Tipping the ski by rolling about its lengthwise axis would be done by moving the knee out with a movement from the hip joint.  Your leg has sufficient mass that this could result in a change to COM (if you have enough range of motion in your joints) and therefore could require corresponding movements to maintain balance.

• Raising and lowering the tip of the ski that is still in the air changes the skis position relative to the snow without any lateral pivoting or change in edge angle.

Tipping by flexing/extending the ankle should be pretty close to an isolated movement, again because tip/tail movements balance each other.  However, I can't think of a practical application of this movement either.

Tipping with no pivotting or pivotting with no edging are perhaps better examples, but there's still a significant balance component, so I wouldn't think of these as examples of complete isolation.  Rather than isolated movements, it would be more meaningful to me to describe this in terms of  excluded movements.
Quote:
Originally Posted by justanotherskipro

In a recent thread we were discussing movement classifications and the term isolated came up. Two understandings of the term were discussed and debated. Without getting back into that debate I promised I would re-post some examples of truely isolated movement as defined by the absence of other skills in these movements. I though it would be fun to see how many of these movements we could come up with. Here's my four...
• Picking a ski up off the snow doesn't involve changing the edge angle, or pivotting the ski
• Pivotting the tip of that ski we have in the air moves the tip left and right but doesn't include any pressure or changing the skis edge angle
• Tipping that ski in the air involves rolling it over along it's long axis with no pressure or pivotting involved
• Raising and lowering the tip of the ski that is still in the air changes the skis position relative to the snow without any lateral pivoting or change in edge angle.
Along with these and whatever additional movements we can think of, I also wonder just how many of these would be used while actually skiing?

I can't help with the first question, but as to the second, most of these moves in isolation have uses in actual skiing.  I use them myself and I've seen them used by a wide variety of skiers.

#1.  Making a complete and total pressure transfer to the outside ski--and ensuring it stays there.
#2.  One-footed carved turns; in some cases the ski in the air must be steered in order to remain parallel.  Yeah, I'm reaching a bit on this one....  Can't think of a good reason to actually practice this move other than maybe for balance.
#3.  A good move for turn initiation in difficult snow conditions (or for less advanced skiers in any snow conditions), or when you are running slalom gates and you need your turns to happen fast.
#4.  Used for fore-aft adjustments (and will do wonders for your one-legged skiing).  If you drop your tip you will move forward, if you raise it you will move aft.  This season I'm going to be very focused on fine tuning my fore-aft balance and I hope to incorporate this movement better into my skiing.
JASP, isolation of skills is a great way to focus on and refine them.  It really gets fun when you isolate, then combine them.
Quote:
Originally Posted by therusty

There are some who argue that tipping a lifted ski is actually used in actual skiing.

And there are also those who say anytime you're sliding downhill with two planks on your feet you're actually skiing.
E thanks for playing! I like what you came up with.
• Although I'd be very careful about pivotting a totally flat ski since the leading edge will more than likely catch and totally spontaneous edge engagements of this sort are know to cause injuries to the shoulder and hip. We cheat a little in pivot slips and pivot entries by raising the forward edge enough to avoid the "smack the snow as hard as you can with your body" maneuver.
• The edge change in the air corresponds to leapers which is an alterative to pivots slip maneuvers in our cert tests. An edge change but no pivot or pressure until after you land. I saw Bode land on the back side of a bump and the skis engaged so smoothly that it looked like he had never let the snow.
• The pivot of the inside leg with the ski in the air is a very good example of an isolated rotary move even when we are doing so to match what the outside ski is doing.

MM, yes pre adjusting your stance is required for the alignment test maneuver.
Isn't the pivoted ski in mid-air a good example of an anti-rotary moved when used in a javelin turn?

Not sure about the anti part since you are still pivoting the ski. How about a 360 in the air, Jelly roll, Mute grab, etc...Park and pipe skiers do a lot of this type of stuff. So do the freeriders when they are negotiating a cliff face and hop / pivot turns are a matter of survival.

This thread was an exercise in demonstrating that even simple isolated ski movements aren't all that simple. I was surprised by some of the examples but I noticed that almost all of the maneuvers mentioned require much more than a simple one for one "do this single isolated body move to produce a single isolated outcome". So in many ways E and SD are right about how a good skier can isolate a skill without affecting the other skills being used. So is being able to break a move down into component parts an important teaching skill. Althought the teaching doesn't ever end there because the studentrs also need to know what happens when they start to make the skis move in two, or three of these classifications simultaneously like Rick mentioned? Add to this the idea the forces involved may not change but in diiferent parts of the turn their effects on us and the skis can change dramatically. So a movement in one phase of the turn might not work very well in another phase of the turn. All in all skiing is about matching body movements to how they affect the interaction between the skis and the snow. We explored isolated outcomes briefly but is should be obvious that a complex combinations of skills and outcomes are involved in performing even the simplist of drills.

Edited by justanotherskipro - 9/28/09 at 8:28pm
In that move, the rotation is the pelvis rotating atop the stance ski. The ski tips being above each other is a visual cue that you've rotated enough. It's not about rotating the femur of the free leg in the hip socket or twisting the lower leg.

I agree E, but in the long run regardless of the mechanics the non stance ski rotates relative to the stance ski.

Quote:
Originally Posted by Ghost

Hold out your hand flat in front of you, palm down.
Apply a pure translation, i.e.  move it right, move it left, move it forward, move it backwards, move it up, move it down, all while keeping it's orientation the same.
Apply a rotation about an axis in line with your forearm, keeping it's centre of mass at the same location without letting it rotate about any other axis.
Apply a rotation about an axis perpendicular to both that axis and an axis perpendicular to the surface of your palm without letting it translate, or rotate about any other axis.

Can you do it?  I bet you can.  It may be a bit tricky for some people, because the hand being attached to the arm may force you to move you body as well and you may have trouble coordinating it just right without letting any non-called for moves if you've been drinking.  We've all learned to get our muscles to cooperate to move our hands just so.

Can you do it with your foot?  With a ski attached?  While skiing?

Apparently some people can't.

I have argued this point before, but this seems and appropriate place and time to revisit a biomechanical fact.   Can you twist your foot left or right without tipping it (inversion/eversion)?  Don't rotate your femur, just turn your foot.

Or....Can you invert or evert your foot without it twisting/rotating?

Can these two movements be separated?  Is this a good thing for skiing?  How can these two simultaneous movements benefit a skier?
Jasp,

In a javelin turn there is sufficient change in the orientation of the pelvis to affect edge angle.

Rotation of the foot while skiing is actually the femur rotating in the hip socket. It is true that the forefoot has some rotational capabilities but these are restricted by the ski boot and are used for balancing. As far as inversion and eversion they are a combination of movements. This is a quote from a Dartmouth University anatomy class: "Hence, each movement is a combination of two or more primary movements. Inversion comprises supination, adduction, and plantar flexion. Eversion involves pronation, abduction, and dorsiflexion."
exactly Loki1 on the inversion eversion movemnts, I was just trying to say it in layman's terms.

As for rotation of the foot being femur rotation statement,  I would say that is not exactly accurate.  When the knee is flexed, as in sitting position, The foot can be rotated under the knee joint in conjunction with the tib/fib twisting.  There is no rotation of the femur at all.

My point here and above is/was, some movements can not be isolated as thought.
When the knee is flexed, as in sitting position, The foot can be rotated under the knee joint in conjunction with the tib/fib twisting.  There is no rotation of the femur at all.

Very true.  The knee does have to be bent at 90+ degrees however for that to be true.  So for skiing not a very practical way of applying rotation.
The actual muscles and joints that can be used independently do not correspond with the independent movements usually used to describe a skis motion (rotation about this or that axis, etcetera).  That doesn't take away from the point that you should be able to turn your ski every which way depending only on your will.
Actually, in most ski maneuvers the skills and the movements it takes to change what the skis are doing are not isolated. Several skills are being employed simultaneously. Several movements are being combined as well. A good skier can certainly create an isolated outcome but that isn't how they ski the majority of the time.
As instructors we need to keep a focus on the final objective and that is to help a student develop and apply the skills and the movements it takes to express those skills at a higher level. Performance based outcomes are the litmus test of any lesson. Are the students better skiers when they leave the lesson? In most cases I would say yes. In those few cases where they don't improve they at the very minimum have a better understanding of why they are stuck at their present level. (You can lead a horse to water...)
The way my world view works, is if you teach skills based, then identify the missing skill,  work on it in isolation, show where it needs to be used more in the students skiing, and then try to bring it into their skiing.

If you try to directly teach a combination of the skills, you may as well be teaching movements.
Well let's be clear here. Skiing requires movement. body movements change how the skis move across the snow, so to suggest you don't teach some body movements is hard to accept E.
Edited by justanotherskipro - 10/1/09 at 3:34pm
Extension is a movement that is or can be an application of pressuring ,a skill. There are many movements that apply skills. The focus of building good and timely use of the skills concept still uses movements but the focus is skills based. Aren't we discussing a philosophic difference that aims to create awareness of developing the skills concepts foremost and use movements to blend or enhance them ?

All skiing is movement but good skiing takes advantage of proper and timely skill development and deployment. Isolating a skill will sharpen that skill and maybe E's point is that without a defined focus the skills can be lost in the attempt to make the movement the most important consideration.

I think that would be like making the outcome the priority instead of making dynamic use of the skills concepts lead them to an outcome of their intentions. Using a skills based teaching method will build fundamentals to create options instead of set outcomes.

Aren't our best intentions to leave the student with the ability to adapt and overcome any situation with a good fundamental base by learning how to apply the skills concepts ?
Perhaps. However, I think that not all students would understand or be interested in the distinctions of the skills that they are learning. Many may not be able to wrap their thinking around them distinct from the movements. The skills may seem abstract whereas the movements are more concrete.

As teachers, it's our role to help the students advance within the context of their current understanding and the expansion that we can bring to that understanding within the confines of a relatively short experience. I will usually discuss the skills on the lift rides as I use my hands to demonstrate what I mean (and invite them to do the same). I don't find that focusing on the skills in on-slope description works as well in many cases. Although I suspect that with those willing to read the EpicSki Technique & Analysis forum, that would not be the case...
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