Where Does/Should Separation Happen?

[Jamt]

BTW, you can create edge without inclination of the COM. Start in a ski stance somewhere in the middle of your vertical range of motion. Rotate your femurs to the right and left -- your knees should be displaced to the right or left. Where did the pressure on your feet go? to the inside of the leg whose femurt is internally rotating and to the outside of the foot on the leg that is externally rotating.

If you are moving with the skis on the snow I don't think you can edge without inclination of CoM. In your example you move the BoS towards the outside leg, and thus you have inclination.

 

[Mike King]

@Mike King I do not think anyone would deny that foot tipping is actually the femur in pelvis bone moving. But it on a different plane than the steering effort that point our skis different ways on a flatter ski.
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Not quite sure what you mean by different plane, but if you are referring to rotating the ski as opposed to creating edge, then I agree with you wholeheartedly. For some reason, rotation seems to have become interpreted as some steering effort that displaces the tip and tail of the ski on the plane of the snow. But rotation is a lot more than that. It can be the primary mechanism of creating edge, particularly in short radius high performance turns.

Note what is happening in the pelvis of the second Warman video above. Not much.

My own journey in improving my skiing has moved from creating edge through inclination and extension to creating and managing edge through rotation of the femurs. I can attest to which one results in ski performance. It has been guided by two current and one former demo team members and an E3 examiner.

Mike

 

[Jamt]

Not quite sure what you mean by different plane, but if you are referring to rotating the ski as opposed to creating edge, then I agree with you wholeheartedly. For some reason, rotation seems to have become interpreted as some steering effort that displaces the tip and tail of the ski on the plane of the snow. But rotation is a lot more than that. It can be the primary mechanism of creating edge, particularly in short radius high performance turns.

Note what is happening in the pelvis of the second Warman video above. Not much.

My own journey in improving my skiing has moved from creating edge through inclination and extension to creating and managing edge through rotation of the femurs. I can attest to which one results in ski performance. It has been guided by two current and one former demo team members and an E3 examiner.

Mike

I agree that most people would be better off increasing their angulation, but at the same time, if you want to reach very high angles you need to incline the CoM a LOT.

 

[Mike King]

If you are moving with the skis on the snow I don't think you can edge without inclination of CoM. In your example you move the BoS towards the outside leg, and thus you have inclination.

True @Jamt , but why? My example was for a static situation to isolate the effect of femur rotation. When you introduce movement of the ski on th snow, the effects of edging introduce new forces. The edging of the ski allows the ski to bend. The bend in the ski causes it to turn. Now the CoM must move inside to balance against the centripetal force created.

 

[Mike King]

I agree that most people would be better off increasing their angulation, but at the same time, if you want to reach very high angles you need to incline the CoM a LOT.

Yep.

 

[razie]

Noting that the discussion now moved into the land of performance skiing, with deep flexion, it's a lot to type for one day, but if you look at performance skiing in a dynamic context (where it tends to be), where the separation of the boots and hips allows coiling and flexing in transition, all you need to do is make sure you allow them to travel on separate paths, skis and hips that is.

The femur rotation is not an input, not a cause... it could be, but things were set in motion earlier, by un-tipping and flexing out of the previous turn. If I just continue to relax (which is the foundation for separation) and keep the skis engaged, everything works out great. Femur rotation is not the best way to keep the ski edge engaged, just like focusing on upper arm rotation in the shoulder joint is not the best way to write text on fine paper. Extension and foot tipping does... even extension is a secondary concern, btw.

If you focus on femur rotation (even with extension), you end up pushing the skis to the side, little edge engagement. The edge engagement is achieved by the subtle movements in the foot/ankle.

But, as usual, YMMV, as it should.

If you put your basis on SW's videos, try this one titled "tip the feet - feet are the foundation for edging and balance - tip to engage and release".


or this one:


Again, @Mike King , if you want to focus on rotating the femurs for everything, from balance, to edging to steering to pivoting, and describe all of skiing as "just rotate your femurs", please feel free to. You can also ignore the fact that without flexion and extension of the leg, as separate and bigger movements, most of that is not even possible. I don't - I prefer to look at tipping as a foot action and counter as a hip action, the femurs are just connecting them (and they have their use as well, at times).

Using the arm example, I'm more interested in expert calligraphy rather than punching holes in cardboard.

 

[Doby Man]

Razie, more specifically, femur rotation is an active input for knee angulation and a passive output from the ski in an edge locked turn.

A key skill blend for separation is the ability to roll the femur to the inside while rotating the adjoining hips to the outside in the “opposite direction” simultaneously. While rolling the femur to the inside gives us angulation from the flexed knee, turning the hips to the outside allows for angulation from the flexed hip. So, we are getting accumulative angulation from the hips and femurs, directly adjoining body parts rotating in opposite directions, all requiring flexion to happen, the essence of separation and a crowning achievement of skill blending. Basically, we can’t angulate without rotation and flexion. They all work together to be able to function. The organically homeostatic nature of alpine technique where almost all function is omni-dependent.

 

[Mike King]

The path to an engaged ski rather than pushing lies in femur rotatation and proper alignment of the pelvis to the ski. Rotating the pelvis or hip to the outside ski can (not will) result in excessive tip lead, an aft position along the ski, and some other move to change edges like a stem and push off.

 

[James]

...edging of the ski allows the ski to bend. The bend in the ski causes it to turn. Now the CoM must move inside to balance against the centripetal force created.

Yes, but. Your example has all the time in the world. If you are going to make a high edge angle turn in a limited amount of time there simply is no time for this slow development. For the turn that is coming, you will need lots of inclination in order to handle the forces and get the edge angle. That's not really in doubt if you think about it. Most recreational skiers don't get there because when they go fast they make very shallow turns. However, it is totally possible, and is done all the time, to do these turns requiring high edge angles. We tend to think it's just racers because that's the images we have. Free skiers tend to be shot in powder, or on huge Alaskan faces from far away and on slopes whose pitch is in multiple directions and changing.

I think it will make more sense if you work backwards rather than forwards. Rather than edge angles and forces develop, go to the point of maximum edge angle and inclination and work back. How did they get there? I posted this photo of Mikaela at Vail in 2015 in the Spot Ice thread:

From the transition to the next image, where the ski is just starting to hook up, there's a huge change. The ski is at 60+ deg of edge angle, and her inclination is prob that too. She needs to be inclined that much, because of the force that's coming. The ski bends, and skier/ski move towards each other bending the ski more to make the turn. There's tremendous force so the ski holds, and then past the gate she'll decrease inclination rapidly and start over. And/or have the skis cut under and the body vaults over. Depending on what's coming.

So, being conservative, let's say she's got 20ft (6m) to make that move. 27mph is 40ft/sec. So she has 1/2 a second to make the move. And it's probably more like 1/4 sec. So to go from 0-60 deg inclination in 1/2 sec, you've got to start inclining 1st. It's not a pure lateral move, but also towards the coming arc, to bend the ski for the turn.

Some groomer skiing with Marcus Caston. Posted by @BrianFinch in the Separation thread.

 

[Mike King]

Well, when I look at that photo montage, I see how inclination and edging require rotation of the femurs. As her body moves from inside to inside, her femurs are also rotating. The extension of her outside leg allows the skis to move away from her, and the flexion allows them to come back under her.

Mike

 

[Mike King]

Again, @Mike King , if you want to focus on rotating the femurs for everything, from balance, to edging to steering to pivoting, and describe all of skiing as "just rotate your femurs", please feel free to. You can also ignore the fact that without flexion and extension of the leg, as separate and bigger movements, most of that is not even possible. I don't - I prefer to look at tipping as a foot action and counter as a hip action, the femurs are just connecting them (and they have their use as well, at times).

I don't know where anyone got the idea that I think all of skiing is simply femur rotation. That's not my view at all. But the skills, and the fundamentals, are not as disconnected as they are often presented. Skiing is a blend of the skills and fundamentals, and high performance skiing is even more of a blend.

 

[razie]

I don't know where anyone got the idea that I think all of skiing is simply femur rotation. That's not my view at all. But the skills, and the fundamentals, are not as disconnected as they are often presented. Skiing is a blend of the skills and fundamentals, and high performance skiing is even more of a blend.

Maybe...

Edging is caused by rotating the femurs.

and...

How is the edge created and released? Rotation of the femurs.

or...

To change the edges and increase edge, the primary mechanism is rotation of the upper legs, e.g. the femurs.

So, pretty much all your posts repeatedly underline the belief that femur rotation is solely or primarily responsible for edging... despite my and others emphasizing that other movements are important and active and that specific rotation often is just a passive movement, not active/primary... did I misunderstand something in those direct and absolute statements? Did I miss any references to other movements that you may have thought you'd need to "blend" in order to increase edge angles, in any of those posts?

 

[LiquidFeet]

[QUOTE="Mike King, post: 195201, member: 152"]I don't know where anyone got the idea that I think all of skiing is simply femur rotation. That's not my view at all. But the skills, and the fundamentals, are not as disconnected as they are often presented. Skiing is a blend of the skills and fundamentals, and high performance skiing is even more of a blend.[/QUOTE]

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@Mike King, recently you have made numerous posts crediting femur rotation with all kinds of essential things having to do with turns. Below are your words. Yes, I am taking them out of context. Here are my excerpts:

"The path to an engaged ski rather than pushing lies in femur rotatation and proper alignment of the pelvis to the ski."

"But rotation is a lot more than that. It can be the primary mechanism of creating edge, particularly in short radius high performance turns."

"My own journey in improving my skiing has moved from creating edge through inclination and extension to creating and managing edge through rotation of the femurs."

"Changing edges by tipping the lower leg through femur rotation, not knee rotation, establishes early edge, is an important part of aligning the outside hip to the ski, maintaining pressure early in the turn on the outside ski, and bending the ski.'"

"BTW, you can create edge without inclination of the COM. Start in a ski stance somewhere in the middle of your vertical range of motion. Rotate your femurs to the right and left -- your knees should be displaced to the right or left. Where did the pressure on your feet go? to the inside of the leg whose femurt is internally rotating and to the outside of the foot on the leg that is externally rotating. Watching the video above, look at the huge amounts of femur rotation that are present in world cup racing."

"For some reason, rotation seems to have become interpreted as some steering effort that displaces the tip and tail of the ski on the plane of the snow. But rotation is a lot more than that. It can be the primary mechanism of creating edge, particularly in short radius high performance turns."

"Watch this. Particularly the hockey slides. How is the edge created and released? Rotation of the femurs."

"Edging is caused by rotating the femurs. Here's a video by Sean Warman that shows that it is the femurs rotating that is creating edge."

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With those words it appears that you are crediting femur rotation with doing all these things:

--creating edging
--creating engagement of the ski
--managing edging
--establishing an early edge
--maintaining pressure early in the turn to the outside ski
--bending the ski
--releasing the edge
--creating edge without inclination of the COM.

That list certainly covers a lot of what makes a turn work. I can rotate my femurs like crazy and get pivot slips, but no turns.
I've been reading these posts of yours and wondering if you really mean what you are saying about femur rotation as strongly as you've stated it.
Do you?

 

[Loki1]

The reality is that edging movements come primarily from the internal/external rotation and adduction/abduction of the femurs in the hip joint. Flexion/extension can and often do happen at the same time as these movements but are incorrectly attributed to causing edging movements, which they do not, except in a wedge.

 

[razie]

Getting closer, although if one just rotates the femurs and adducts/abducts, one ends up like this:

While if one effectively flexes the leg, allows the hips inertia to take them over the skis while extending the leg, one looks like this:

As it's obvious from this non-fabricated photo, all MS has to do to transition is to relax the long outside leg, let it bend and not care about the femurs... the inertia of the hip does all the rest.

Simple fact is that lateral extension of the leg from a squat includes that which you focus so much on, but is not included in it. Leave the knee flexed for instance while you rotate and abduct the femurs and you'll just look funny.

Kinetic chains can be used in many ways. I can exert rotations in all joints and apply extensions to each to leghten a 3 segment chain, or I can pull on the ends. Some can continue to focus on just one of their many segments (call it femur), but a well trained human brain is very adept at figuring out the details of a complex movement... it's important what you train it on, what movement sequences it relies on to build complex actions.

Anyways... peace. Everyone should ski in whichever way suits them better.

...time for

 

[James]

Getting closer, although if one just rotates the femurs and adducts/abducts, one ends up like this:

Are you trying to prove Mike's point? There's the edging. Get rid of those way too long poles, stop reading the shovels, take off the 50lb weight pushing down on his head, add some inclination, tip lead, and the skis turning under the body, and you've got the static image of Mikaela. Of course that position pulls his hips around because the skis are fixed. Sure, one could overdo it in a turn and let everything rotate around ie rotate the pelvis.

That photo proves as much as if he stood there, tipped his feet and flexed. Nothing.
I'm just fascinated by the theory that athletes view their femurs as things hanging off the pelvis only to connect the tibia.

 

[razie]

He's not turning, though, in that photo?

If he was turning he'd fall right over without inclination, which is actually the point. Without it, it just looks funny and can't turn, cause he would fall over... It's just a static, useless position...

 

[James]

He's got inclination (edit: because of the polygon of sustentation extended with the pole, he's not inclining.)And angulation. And he's also balancing with the pole. (Changes the center of base of support. Com is now centered, no inclination)

I agree about needing inclination to turn. If you're going straight standing equally on both feet, tip one foot to little toe, you will turn if you allow your body to fall that way. Balance point shifts to the other foot , you are inclined.
Now, if we do the other way, tip one foot to big toe, it also depends on what you allow the body to do.
But once the balance point shifts from between your feet, technically you're inclined.

 

[Chris V.]

For some reason, rotation seems to have become interpreted as some steering effort that displaces the tip and tail of the ski on the plane of the snow. But rotation is a lot more than that. It can be the primary mechanism of creating edge, particularly in short radius high performance turns.

The definition of "rotary movements" or "rotational control" has been quite murky in the past. The new Alpine Technical Manual is an improvement, for sure, but it could still stand to be better, with stronger, clearer language on the nature and functions of the movements. Written by committee. I've run into lots of instructors who IMHO had a poor understanding of this subject. The literature hasn't been terribly helpful at conveying a strong foundation of common knowledge generally endorsed by the profession. The new generation of trainers at our mountain have really improved instruction of ski school staff in skiing and teaching principles centered on rotational control. They've helped me a lot. There's some catching up to do.

 

[Zentune]

A large spectrum of ski/snow interaction outcomes can be achieved via femoral rotation (and other inputs). It is FAR too simplistic to say something like “femoral rotation is responsible for edging” alongside a carving video, when I’m fact femoral rotation could be a key component of *un-edging* (aka flattening), for example.

zenny