Dorsiflexion and its role in skiing

JESinstr

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There's a reason the Romans invented the Arch. They knew, that someday, they would be skiing.

arch.jpg
 
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Tony S

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And you pressure the tips of your skis by pulling the feet back.
Btw, the reason for pressuring the ski tips is so you can vary, or tighten the turn radius.
Why the absolutism? Not sure if it's intentional, but your phrasing has overtones all-encompassing stone-tablet knowledge. A lot of very experienced and talented instructors here - and a few interlopers like me - don't seem to think it's so simple.
 

James

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Haven't seen an answer to your question yet.

Anyone else seen this? From the Elan shaped ski designer himself -Jurij Franco

Very interesting!
Where did you find that?
What is the _ mm = _ mm refering to? Second is deflection, what's first #?

Static drill: stand up at home and do 2 body weight squats, noting where the weight is and isn't on the feet. The weight will predominantly travel through the heel - the balls of the feet will stay in contact with the ground. Now imagine lifting an extra 50kg or 100kg? Would we transfer that extra weight to the balls of the feet or leave it over the heel, over the place of power? Obviously over the heel as anything else would be weak.
I think "heels" is a coaching cue for those getting too much on the ball of foot. I'll leave it to those who know about such things.

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Principle #2: The Mid-foot Balance Point
One of the most common technical mistakes in powerlifting occurs when lifters shift their weight onto their toes when squatting or deadlifting. The best way to correct an exaggeration in one direction is with an overcorrection in the opposite direction. Hence, some of the most popular “coaching cues” in powerlifting are “get your weight on your heels” and/or “push through the heels”. The contexts of these cues have been lost for whatever reason and many people have been led to believe that optimal technique actually involves being balanced on your heels. This is certainly not the case.
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http://www.powerliftingtowin.com/powerlifting-technique-the-scientific-principles/
 

no edge

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Great skiers change edge angles to control pressure, but using the whole ski to steer and control the pressure is an important aspect of great skiing. There is more to skiing than 'big toe little toe'.
 

elemmac

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What is the _ mm = _ mm refering to? Second is deflection, what's first #?
The first number is his measurement. In the first shot before loading the ski he shows "179mm = 0mm". So from there 183mm = 4mm (i.e. 183mm - 179mm = 4mm) deflection.
 

JESinstr

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Why the absolutism? Not sure if it's intentional, but your phrasing has overtones all-encompassing stone-tablet knowledge. A lot of very experienced and talented instructors here - and a few interlopers like me - don't seem to think it's so simple.
This is what happens when we take a situation that is normally static (standing) and make it dynamic (moving). People try to justify dynamic situations with static examples.

Not that there are not good points to be made.
 

markojp

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Forebody pressure, or edge angle? Ankles open, or closed? From the feet, or higher up the chain?

greenpantski.jpg
 

Mike King

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Why not both?
Somewhere upchain someone suggested the goal was to pressure the fore body of the ski. Such a goal suggests that it’s (almost?) universally true that pressuring the tips is an objective. My understanding of ski performance is that pressuring the tips leads to displacement of the tails; I.e. the tails do not follow the tails same trajectory as the tips. There maybe times when that’s the ski performance you want, but most high performance skiing is not served by such ski performance. The video that @geepers posted shows what happens to ski shape and edge engagement when the pressure point is moved forward and aft of center.

If the objective is to drift a turn, there are multiple ways to achieve that objective. Moving the pressure point is only one. But I’d argue that in most circumstances, keeping the pressure point in the center of the ski will be the route (and root) to higher ski performance.
 

HardDaysNight

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Rough transcripts of some relevant parts (partly summarised):
Foot platform in boot (around the 5 minute point)
Best way to start with this is the foot/boot interface which allows us to control the ski, manage forces and get the performance we're looking for. To that we need a sound structure.

Static drill: stand up at home and do 2 body weight squats, noting where the weight is and isn't on the feet. The weight will predominantly travel through the heel - the balls of the feet will stay in contact with the ground. Now imagine lifting an extra 50kg or 100kg? Would we transfer that extra weight to the balls of the feet or leave it over the heel, over the place of power? Obviously over the heel as anything else would be weak.
This is why ski racers (who think about these things) do lots of squats from the heel.

So our structure is a tripod: our heel, the ball of the foot and the part under our little toe (the 5th metatarsal-phalanges joint).

Setting up for transition there's going to be primary pressure on the heel, then it does move forward to the ball of the foot. But not at the expense of the heel. We don't get off the heel and push into the ball. As we move forward weight gets levered forward onto the front of the foot but it still travels through the heel. If it doesn't we lose that base of support that allows us to get the power and manage the forces.
The key here is shin/boot cuff.
If we are going to put our weight through our heel we are going to have to get forward from somewhere else, as forward is darned important in skiing. How we move forward is more important than that we did it - if we move forward by pushing our toes down and pushing into the ball of the foot a lot it's going to result in us going back. If we stay on the heel and flex the ankle forward by engaging the Tibialis Anterior (TA) it pulls us forward so the shin contacts the boot tongue. The body mass is still supported by the heel but we now have a lever to drive the front of the ski.
This is so good that, IMO, there’s not much more to say! Impressive guy that JB.
 

no edge

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Somewhere upchain someone suggested the goal was to pressure the fore body of the ski. Such a goal suggests that it’s (almost?) universally true that pressuring the tips is an objective. My understanding of ski performance is that pressuring the tips leads to displacement of the tails; I.e. the tails do not follow the tails same trajectory as the tips. @geepers posted shows what happens to ski shape and edge engagement when the pressure point is moved forward and aft of center.

If the objective is to drift a turn, there are multiple ways to achieve that objective. Moving the pressure point is only one. But I’d argue that in most circumstances, keeping the pressure point in the center of the ski will be the route (and root) to higher ski performance.
 

Wilhelmson

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Somewhere upchain someone suggested the goal was to pressure the fore body of the ski. Such a goal suggests that it’s (almost?) universally true that pressuring the tips is an objective. My understanding of ski performance is that pressuring the tips leads to displacement of the tails; I.e. the tails do not follow the tails same trajectory as the tips. There maybe times when that’s the ski performance you want, but most high performance skiing is not served by such ski performance. The video that @geepers posted shows what happens to ski shape and edge engagement when the pressure point is moved forward and aft of center
This is my rudimentary understanding. I think in our icy conditions some instructors still teach the shins to cuffs method to pressure the forebody to get the whole ski working, or maybe to over correct for back seat and other problems. They can only do so much in an hour or two and that might be a necessary evil to get a skier with worse bad habits using the edges on front 3/4 of the ski.
 

no edge

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I agree that pressuring the tips can lead to washout - especially if you are leaning against the front of the boot. But dorsiflexion allows a use of the front of the ski (and center) to do some great performance skiing... like tightening the radius of a turn, steering (!) which is an awesome sense of motion that skiing offers. Dorsiflexion allows for the use of the forward flex without needing to "pound" it. It also allows the skier to drop down without falling into the backseat. It's a fantastic skill but for me it requires proper boot flex.

I should tell you that I not an expert in analysis or understanding the mechanics... as many in this tread may be. I could tell you that I am unqualified, but I do have a background in using dorsiflexion within a range of skiing. I do have limitations.
 

James

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This is what happens when we take a situation that is normally static (standing) and make it dynamic (moving). People try to justify dynamic situations with static examples.

Not that there are not good points to be made.
In terms of the body, skiing is much more static than most sports. If one foot is a stride length in front of the other that would be extremely unusual. The feet and lower leg is encased in a device that severly restricts movement.
How many beginners have you had that make 10x the move you want them to make?
Skiing is almost slo motion movement, especially at the lower levels. A lot of the dynamics is estimating where to be and what to do in the next moment.

Forebody pressure, or edge angle? Ankles open, or closed? From the feet, or higher up the chain?

View attachment 75153
It's one picture, but he's pretty centered.
In ski boots, the ankle is pre dorsiflexed, closed. It's all relative.

IMG_6525.JPG

Sole Boot Lab, Chamonix
 

Corgski

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Firstly an edit for my previous post: I am a strong believer in skiing from the feet, my advice to relax feet was really only for those who have tried to use their TA to do all the heavy lifting as described in some posts. Relaxing feet will give your excruciating TA a break, shift some load onto your hamstrings and get you down your last run without calling patrol for help. Yes, I have tested it out, yes one's TA can really, really hurt.

There is a difference between coaching cues and a working mental model of skiing that you can take on the hill with you. I have no issue with any of the TA coaching cues, but it is presented as a model and when taken that way it does not work. It assumes a particular problem which not everyone may have and it seems to assume complementary muscle activation which may or may not happen (credit to @François Pugh for the idea of complementary muscle activation). If you add a lot of context to what is written, the issues I have with it potentially go away.
 
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Tony S

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In terms of the body, skiing is much more static than most sports. If one foot is a stride length in front of the other that would be extremely unusual. The feet and lower leg is encased in a device that severly restricts movement.
LOL. Imagine if this crew had to discuss tennis.
 

JESinstr

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JESinstr said:
This is what happens when we take a situation that is normally static (standing) and make it dynamic (moving). People try to justify dynamic situations with static examples.

Not that there are not good points to be made.
In terms of the body, skiing is much more static than most sports. If one foot is a stride length in front of the other that would be extremely unusual. The feet and lower leg is encased in a device that severly restricts movement.
How many beginners have you had that make 10x the move you want them to make?
Skiing is almost slo motion movement, especially at the lower levels. A lot of the dynamics is estimating where to be and what to do in the next moment.
While there is nothing in your response with which I disagree, This is truly a case of glass half empty/half full.

The problem most instructors have with beginners is STOPPING the 10 x move that you DON'T want them to make. And the problem goes deeper that just moves IMO
.
Take for example, the moving walkway at the airport. You approach making fairly dynamic moves (walking and if your late for your plane, running). Your eyes input forward travel to the brain. You enter the moving walkway and cease the dynamic moves (stand) . Yet your eyes keep inputting forward movement to the brain resulting in a temporary (depending on coordination) impending loss of balance which most easily adjust to.

For beginner skiers, it's just the opposite. They are standing still and suddenly, their eyes and other senses detect movement and much worse for the brain's survival component, acceleration. But wait, they are standing at 0x movement and the skis just started accelerating out from underneath. the length of the skis inhibit fore/aft dynamic adjustment. Call in 10x moves from the upper body to try and save the day. Bad move.

IMO this is why I find this thread very interesting and important. For those of us who believe that we start at the foot, dorsiflexion or at least the concept thereof may be the key to getting beginners off on the right foot....excuse the pun.
 
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LiquidFeet

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Might this video impact the discussion in some way?
Note that the shield hangs and its lower edge moves fore-aft.
PSIMAN's anatomy is different from ours... no ankles to dorsiflex.
But, there are indirect similarities. [Also, I've heard that PSIMAN falls more often that this video implies.]
 

Rod9301

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Somewhere upchain someone suggested the goal was to pressure the fore body of the ski. Such a goal suggests that it’s (almost?) universally true that pressuring the tips is an objective. My understanding of ski performance is that pressuring the tips leads to displacement of the tails; I.e. the tails do not follow the tails same trajectory as the tips. There maybe times when that’s the ski performance you want, but most high performance skiing is not served by such ski performance. The video that @geepers posted shows what happens to ski shape and edge engagement when the pressure point is moved forward and aft of center.

If the objective is to drift a turn, there are multiple ways to achieve that objective. Moving the pressure point is only one. But I’d argue that in most circumstances, keeping the pressure point in the center of the ski will be the route (and root) to higher ski performance.
When you pressure the tips, the ski bends more, so you shorten the turn radius.

It's still a carved turn
 
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