Dorsiflexion and its role in skiing

[Scruffy]

Do you have any evidence of that? Everything I have implies that even a slight adjustment fore or aft leads to a skidded ski.

Then again, there may be no such thing as a ski turn that is perfectly carved...

It's all about DIRT, right? I think you even said up thread that you get forward at the top of the turn to engage the tips quickly, then move progressively aft as the turn unfolds. That's standard race training. If you get aggressively forward and stay there throughout the turn, then yeah, you can likely skid the tails out of the track the forebody cuts in the snow. It really depends on one's body mechanics based on their physical proportions and how much forward we're talking and delta ramp angles and on and on. So much to it.

Tom Gellie appears to be of the opinion that no orthotic or footbed is needed and that they may, in fact, hinder your ability to use the three arches of the foot. I'm not quite convinced yet, but his logic is persuasive...

Cool, I didn't know that, but I agree with him. I'll have to pay for his videos later this year when I'm ramping up for ski season, hopefully. There's a lot that goes on when you don't block pronation of the foot in the ski boot. From planter fascia tensioning, which tensions the entire superficial front line readying it for action ( also guards body against injury), to everting the foot to get higher edge angles, and inward rotating the tibia, thus gaining passive (free) rotation during the turn. I don't have time to get into it too deeply right now, but it's fascinating stuff. It's pretty easy to try; just take out your ortodics or footbeds ( assuming you don't have a foot issue that requires an ortodic ) and try skiing for a few days. You'll need to replace the footbed with a flat one to replace the volume removed. A good shoe store will have them, or online.

 

[markojp]

What's missing in the 'let's throw the footbed under the bus' idea is that there are a number of different footbed 'plugs' and methods/degrees of molding available. There's also a good deal of examination of the amount of lateral wrap and 'stiffness' of footbeds going on at the WC level. Like all else, IMHO, there are a LOT of variables. I don't believe it's a binary desicion making process. I also know that my own foot is laterally mobile enough that I DO palpably feel a benefit in lateral response WITH a custom footbed (mine aren't posted or completely rigid at all). But all that's just like my opinion, man. (Dudeism emoji here)

 

[Mike King]

@markojp, I'm not sold yet on the idea of no footbed. Tom, and I believe Dave McPhail, believe that the structure of the foot is really important to athletic performance. Many boot fitters and pedorthitists build footbeds that provide a rigid support under the arch of the foot. Tom believes this is limiting to athletic performance. He believes the arches of the foot and incredibly important to being able to effectively use the foot and ankle as class 2 levers (ability to transfer large loads). They are also important to use as class 1 levers (for absorption). So a footbed that restricts the ability of the arches may not be the best choice, according to Tom.

One of our trainers in Aspen, a guy going for the demo team who has just missed the cut the previous two tryouts, has been working with a World Cup coach on his skiing. That coach took his footbed and "ground it down to just about nothing" to apparently give him less support from the orthotic.

Tom is using a carbon fiber footbed with a bump (pointing down to the zeppa) with a piece of the Sidas footbed (flat, unfolded) in his boot. The carbon fiber (flat with bump) came from a sprint coach.

It's all interesting and thought provoking.

Mike

 

[Scruffy]

What's missing in the 'let's throw the footbed under the bus' idea is that there are a number of different footbed 'plugs' and methods/degrees of molding available. There's also a good deal of examination of the amount of lateral wrap and 'stiffness' of footbeds going on at the WC level. Like all else, IMHO, there are a LOT of variables. I don't believe it's a bionary desicion making process. I also know that my own foot is laterally mobile enough that I DO palpably feel a benefit in lateral response WITH a custom footbed (mine aren't posted or completely rigid at all). But all that's just like my opinion, man. (Dudeism emoji here)

The foot is an amazingly complex organ, and everyone's feet are different, so yeah one solution doesn't fit everyone. It's nice to see that there's an interest and experimentation at the WC level and other's like Tom Gellie, but, of course, McPhail has been there talking about this for about 20 years or more now.

 

[Steve]

Returning to my knife carving analogy. I was dicing some raw chicken breast yesterday and was reminded that another key to effective cutting with a sharp knife is not pressing down hard, let the knife do the cutting.

Move along the edge, don't push down on the blade. Sounds familiar to me.

 

[ted]

@markojp, I'm not sold yet on the idea of no footbed. Tom, and I believe Dave McPhail, believe that the structure of the foot is really important to athletic performance. Many boot fitters and pedorthitists build footbeds that provide a rigid support under the arch of the foot. Tom believes this is limiting to athletic performance. He believes the arches of the foot and incredibly important to being able to effectively use the foot and ankle as class 2 levers (ability to transfer large loads). They are also important to use as class 1 levers (for absorption). So a footbed that restricts the ability of the arches may not be the best choice, according to Tom.

One of our trainers in Aspen, a guy going for the demo team who has just missed the cut the previous two tryouts, has been working with a World Cup coach on his skiing. That coach took his footbed and "ground it down to just about nothing" to apparently give him less support from the orthotic.

Tom is using a carbon fiber footbed with a bump (pointing down to the zeppa) with a piece of the Sidas footbed (flat, unfolded) in his boot. The carbon fiber (flat with bump) came from a sprint coach.

It's all interesting and thought provoking.

Mike

Any more info on his footbed? Can't quite conceptualize this.

 

[KingGrump]

Returning to my knife carving analogy. I was dicing some raw chicken breast yesterday and was reminded that another key to effective cutting with a sharp knife is not pressing down hard, let the knife do the cutting.

Move along the edge, don't push down on the blade. Sounds familiar to me.

I don't know much about skiing. I do know a lot about cutting with a knife.

Cutting with a knife effectively and efficiently requires a much more complex motion than most folks realized. Much is also dependent upon the knife utilized, the item being cut and the final desired product.
To cut a completely thawed boneless chicken breast or thigh efficiently would require a more complex motion than "simple slicing." Aka moving the knife along the edge.
For me, the process would usually go something like this. First start with a 8" or 10" chef knife. Would be nice for the knife edge to have a belly rather than a flat straight edge. Engage the chicken lightly with the front edge of the knife about a quarter length of the knife back from the tip. The early engagement is both for cutting accuracy and safety. The heel of the knife at this point is higher than the tip. Stroke the knife edge forward while at the same time press down on the knife - slightly. The two movements are to be synchronized so the both complete at the same time.
There is also very subtle changes in pressure distribution along the knife edge during the entire cut. Hard to see but easily felt. More pressure toward the front at the start of the cut rolling back toward the heel at the end of the cut.

The above is based on years of restaurant experience.

 

[Mike King]

Any more info on his footbed? Can't quite conceptualize this.

 

[Tony S]

 

[LiquidFeet]

So. The fulcrum, when Tom G talks about the foot doing the Class 2 lever thing, is where?
And what is the load?

 

[geepers]

So. The fulcrum, when Tom G talks about the foot doing the Class 2 lever thing, is where?
And what is the load?

Fulcrum is at the ski tips. Load is the skier. Like in this in the side view where he presses the tips into the mogul.

 

[LiquidFeet]

Thank you, @geepers.
I was wondering if all these lever parts were somehow contained within the foot itself, since people have posted about Gellie talking about footbeds and tightening the foot.

 

[Mike King]

Yep, @LiquidFeet, the levers are in the feet and ankles. The "flat" footbed allows the foot and ankle, when stiffened, to access the three arches in the foot (lateral, medial, and transverse) and converts the normal action of the ankle (class 1) to a class 2 lever.

So, what's the difference between these types of levers? Class 1 levers generally do not multiply the force or motion, but are good for absorbing impacts. Class 2 levers move large loads with less effort. They are generally slower to operate (more movement required to move the load). Most of the joints in the body are class 3 levers. These require more effort, but amplify speed.

Mike

 

[Mike King]

Fulcrum is at the ski tips. Load is the skier. Like in this in the side view where he presses the tips into the mogul.

View attachment 102496

True for what he is trying to get the ski to do -- have a pivot point on the tip or the tail of the ski in the moguls. But to achieve that, he is getting a fulcrum in the heel and ankle, allowing transfer of the mass of the body fore and aft with relatively little movement of the body.

Mike

 

[LiquidFeet]

I keep my ankles more-or-less stiff. This reduces the number of acting hinges in the lower body from three to two. Hips and knees are opening and closing, but not the ankles (well, mostly not). Two hinges is plenty enough to keep the CoM where it needs to be over the skis, fore-aft-wise. This tension in the ankles, reducing active hinges to two, enables more precise control of the under-ski pressures than possible with a third hinge joint opening and closing.

Does this sound related in any way to what Tom Gellie is talking about? I remember someone referencing Gellie's ideas about tension in the ankle and foot.

 

[Mike King]

It is definitely part of the equation.

 

[geepers]

Cutting with a knife effectively and efficiently requires a much more complex motion than most folks realized.

Ah...yes. But that's not really the issue. So... when you are preparing pure carved chicken do you tighten the radius of the cut by pressing more on the tip of the knife?

Don't know about others however I use a serated knife for dicing tomatoes. That way I can keep my (admittedly low) speed up without running too much risk of stabbing fingers. Of course more discerning cooks probably skin them first... In any event has anyone tried serated edges on their skis? And at what point do we take analogies too far?

 

[Steve]

I actually do have a vague memory of serated ski edges, I don't recall what brand or what happened with them though.

It's similar to an old analogy about a ... oh never mind.

 

[geepers]

True for what he is trying to get the ski to do -- have a pivot point on the tip or the tail of the ski in the moguls. But to achieve that, he is getting a fulcrum in the heel and ankle, allowing transfer of the mass of the body fore and aft with relatively little movement of the body.

Mike

I'm specifically referring to the side on view where he has the tips engaged. Rather then the whole run.

So, what's the difference between these types of levers? Class 1 levers generally do not multiply the force or motion, but are good for absorbing impacts. Class 2 levers move large loads with less effort. They are generally slower to operate (more movement required to move the load). Most of the joints in the body are class 3 levers. These require more effort, but amplify speed.

Got to keep in mind that with these levers mechanical or speed advantage depends on the relative locations of fulcrum, load and effort. It's entirely possible to have no mechanical advantage with a class 2 lever.

I keep my ankles more-or-less stiff. This reduces the number of acting hinges in the lower body from three to two. Hips and knees are opening and closing, but not the ankles (well, mostly not). Two hinges is plenty enough to keep the CoM where it needs to be over the skis, fore-aft-wise. This tension in the ankles, reducing active hinges to two, enables more precise control of the under-ski pressures than possible with a third hinge joint opening and closing.

We diverge rather largely here. I've been working on keeping the ankle as mobile as possible given that it is constrained in a ski boot. A general rule if my skiing is off it will be joint mobility and the ankle is the prime suspect. CSIA Tech Ref #1. "Use of all joints helps maintain balance and manage the forces acting on the ski and the skier." Primarily they refer to ankles/knees/hips.

Question: how do you go with one legged drills?

 

[Tony S]

I keep my ankles more-or-less stiff.

You do? Really? In all planes? Not challenging, just thinking aloud. I feel like I spend thought and energy doing stuff with my ankles. For example, trying to close them at certain points, sometimes opening in the belly of a carved turn.Maybe you think of this as stiffening? I definitely try to roll them laterally and medially inside the boot as part of tipping.