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How Much Dorsi Flexion Do You Need?

post #1 of 22
Thread Starter 
Recently, there have been many comments on dorsi felxion. I find this very interesting, since the ability to dorsi flex diminishes in age. Keep in mind this is a GENERAL statement! Obviously, there is a "use it or lose it" thing that happpens here.

My question is, has anyone gone so far into ski technique geekdom that a numerical range has been established as to how much dorsi flexion is needed for pro vs. recreational skiing?

Or is the concept just a myth?
Thanks!
post #2 of 22
Hi Lisamarie,

What a question!!! Ideal dorsiflexion should be 10 degrees, or more. It is measured from sub-talur nuetral. It takes practice to find nuetral. If nuetral is not found, a very false reading will be taken, usually five to seven degrees too much. Nuetral is found by moving the ankle around until a resistance is felt. Measure between the foot and tibia. Then pressure is applied to the foot and the angle between the foot and the tibia is measured again. The difference is the dorsiflexion angle. This is extremely important in the building of footbeds. It will tell the technician if extra posting will be needed under the heel.

Why is this angle needed to be known by skiers? Let's say you are buying a new pair of boots. You know that one of your feet have a dorsiflexion of 8 degrees. You will know that if you try to fit into a boot that has 12 degrees of forward lean, it will feel short in your size. This is due to you sliding forward in the boot to accomadate your lack of dorsiflexion. So, I look for a boot that has adjustable forward lean. Heel lifts will also accomadate the lack of dorsiflexion. Care should be taken by the bootfitter to assure that dorsiflexion be measured at the time of boot selection. If a person is really hung up on a particular model boot, some modifications may be needed to get a satisfactory fit. By modification, I mean relocate shell rivets to modify forward lean to fit a particular dorsiflexion.

I hope that I have not confused anyone who reads this. Bootfitting is a complicated task the requires a fair amount of expertise to be competitant. Unfortunatly, this is not always the situation.
post #3 of 22
Lisamarie, there are no technogeeks here. Dorsiflexsion normal range is from 12 to 24 degrees roughly.
post #4 of 22
Apparently if you want to keep your feet warm, forget the squinching the toes thing. Instead, Dorsiflex then relax, repeat for several minutes. I've been told this actually pumps blood into the foot. It seems to work whereas that toe wiggling business is just too hard!
post #5 of 22
Quote:
You know that one of your feet have a dorsiflexion of 8 degrees. You will know that if you try to fit into a boot that has 12 degrees of forward lean, it will feel short in your size. This is due to you sliding forward in the boot to accomadate your lack of dorsiflexion.
Ric, perhaps you can elaborate on this. I recently tried the Dobermanns on and they felt short- like a hiking boot. This was very weird to me. I don't think my foot was not sliding forward at all though, it was quite tight.
post #6 of 22
Quote:
Originally posted by Rick H:
This is extremely important in the building of footbeds. It will tell the technician if extra posting will be needed under the heel.
What is posting?
post #7 of 22
Sorry for the stupid question here, but I've seen a couple references in this forum lately to "dorsi flexion". For those of us that slept through Anatomy 101
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  • What is dorsi-flexion?</font>
  • How do you know how many degrees of it you have?</font>
Thanks,
Kevin
post #8 of 22
Thread Starter 
Mia Culpa! Dorsi Flexion is when your toes flex in the direction of your shin, as opposed to plantar flexion, when they point towards the floor. Dancers call dorsi flexion simply "flex" and plantar flexion "point".
post #9 of 22
Tog, in order for the tibia to remain encased by the upper shell, the foot has to do something to accomadate the lack of dorsiflexion. The heel will come out of the pocket (probably never in it), and the foot moves forward to open the angle between the foot and tibia. Hence, the toes against the front of the toe box.

Epic, There are two materials (usually)in a footbed. The top sheet and underfoam. This underfoam, or plastic, is milled to create corrections in the footbed to accomadate the foot. This final form is called posting. Let's take the lack of dorsiflexion, ie, reduced angle. By adding a 4 millemeter lift under the heel, the dorsiflexion comes into the normal range for ski boots, of 10-12 degrees. This material that is not removed is called posting. Another common posting situation is more material is left under the inside ball of the foot to accomadated a twisted, flexible forefoot. I have 8 millemeters of "varus" built in to my footbed, so that I can find my little toe edge. That is a bunch!

Kevin F, I have 10 degrees dorsi in my right foot and 8 degrees in my left foot. It is not uncommon to see as much as 15 degrees or as little as 6 degrees. I suspect breaking my left ankle twice, has a lot to do with the difference between my left and right feet.
post #10 of 22
As far as the actual numbers for ideal dorsi flexion that would vary a great deal. The boot itself and internal ramp angle, height of cuff proportionate to lower leg, shape of boot back relative to shape of lower leg, size and shape of calf muscle and proportion of tibial length to femoral length are all factors that could make a functional value for one a recipe for pain, dysfuntion and inefficient biomechanics for another. I would suggest that 10 degrees would be close to a minimal functional flexion for most skiers. Most boots would eat that up with the static position the skier is in. This would leave the skier at or close to end range of flexion which makes dynamic balance difficult to maintain, can create displacement of the foot in the boot as mentioned above as well has contribute to or create much pain along the bottom of the foot or at the metacarpal heads as well as often create pain mistaken for pressure along the front of the shin. There is certainly no myth in the importance of dorsi flexion and for the fellow who asked dorsi flexion refers to the upward articulation of the foot at the ankle joint.
post #11 of 22
Thread Starter 
Cool, thanks! If you don't mind, a few more quesstions. When I first started skiing I was told that having weak tibialis anterior, which in SOME cases leads to limited dorssi flexion is ONE of the reasons people end up in the backseat.
True or false?

Also, is there any importance of plantar flexion?
Thanks again! [img]smile.gif[/img]
post #12 of 22
How much D/F do you need? That's easy- enough to remain in balance!
After all- that's what it's used for. As terrain changes, so does our stance, slightly, adjusting from the ankle to remain centered. As we flex (wanting to remain centered), the degree of D/F will change.

Obviously, each individual will have a different amount to draw from. It the amount available isn't sufficient, then you can deal with it in a remedial sense. Heel lifts, adjusting boots, or stretching exercises which increase the range of movement in the ankle. Remember- boots themselves can limit the range of D/F if they are too stiff.

Another thing to think about- the muscular action of D/F is actually fairly weak, with limited range. Focus on relaxing the ankle joint as you flex, and you may find that the range increases dramatically! (and you'll stay more centered!) But keep the down pressure on the back half of the foot while doing this.

So- how much does it take??? That's up to each individual! To say it takes some set number is completely unrealistic.

:

By the way- too much D/F actually weakens the stance!

[ February 27, 2003, 06:20 AM: Message edited by: vail snopro ]
post #13 of 22
I want to toss a wrench into the works. Last Sunday night Bob B did an m.a. session @ Eldora and this topic arose. I recalled him once saying "one could ski in concrete ski boots".

He pulled up his stick man animation of a skier in moguls. It is the animation in which the stick figure essentially "backpedals" through moguls.

Bob pointed out that the angle between the stick figure's foot and tib/fib does not vary. The angle is maintained via other joints/sockets/mechanisms.

So.....we obviously don't have the perfect world of an animation figure, however, how very much do we "flex" our ankles in the world of foamed/fitted boots?
post #14 of 22
VSP- That was weird....our stars must be aligned!
post #15 of 22
LM-
Interesting question about P/F! Of course it's useful. Imagine running into something stiffer than the snow you are currently in. As your body wants to continue moving forward as the skis slow, you use P/F to prevent yourself from going over the handlebars! Thats the first line of defense.

So- anytime you find yourself too far forward (and many skiers are) the P/F is the mechanism used to correct that.

:

7" yesterday, 6" last night! No lift lines! A student that can ski about anywhere.

Sorry- time for me to go to work!!!

[ February 27, 2003, 06:22 AM: Message edited by: vail snopro ]
post #16 of 22
Our inability to balance is mostly product of skiing on the groomed slopes. We can learn proper balancing moves in one season, skiing on un groomed terrain, but instead we are trying to perfect some “stationary” moves on corduroy. This way it will take 100 years to accomplished the task. Technology?(In this matter) Quote: “one could ski in concrete ski boots”
post #17 of 22
JP,
You make a good point about groomed slopes, they certainly do enable the balance challenged skier to more easily exist in his inefficient positions. Undulating terrain will provides that skier an immediate wake up call.

I remember racing in Europe years back. Things were so different than over here. They would set GS and DH courses on ungroomed slopes with moguls up to over your knees, and would run DH's with fog so thick you couldn't see half way to the next gate. Stuff you would never see happen over here. Certainly does something for ones balance skills!!

That said, I don't know if I would totally preclude the ability to develop balance skills on groomed slopes. They won't readily develop spontaneously there with no concious effort or instructional guidance, but groomed runs do in fact offer the best arena for an instructor to introduce new planes of balance to his students and highly refined skills can be developed. It just that it must be a dedicated pursuit. :
post #18 of 22
Thread Starter 
Great stuff so far. Now here's an interesting thing, one of the other reasons I asked this question.
This season, anyone who came to my ski fitness classes who complained about constant excessive quad burn while skiing had relatively limited dorsi flexion. Not sure if that's a coincidence or not.
My advice is always to have their boots looked at, an d to take a ski lesson, but I found the dorsi flexion quad burn thing interesting.
post #19 of 22
Liasmarie,

About the burning quad thing. I have a couple thoughts.

First, how did you ascertain limited dorsi flex. Did you measure the skier outsite of their boots? Was it an observsation ofn the skier limited ability to flex the ankle while in their boots? Just wondering if a to stiff boot could have played a role.

Also the idea that quads would burn more in the skier who can't enter a deep flexed ankle position would tend to make sense. With normal dorsi flexion capacity flexion used to facilitate edging and terrain absorbtion is a combination of ankle and knee flextion which keeps the center of mass over the boots. Without the ability to dorsi flex adaquately more flexion is assigned to the knee and waist, and the hips end up in a more aft position. This is a higher stress position for the quads. You can stand on the floor and enter the two positions and feel the difference in the quads. It would make sence then that skiers with more limited dorsi flex would experience more quad stress. Hips over the feet is a much more relaxed position.

Untill proper equipment corrections can be made to assist the problem it can be somewhat alleviated by utilizing a more upright position while skiing, depending more on inclination to apply edge as opposed to angulaion. This keeps the hips more over the boots and gives the quads a break! It imposes some technical restrictions on the skier but will get him down the hill in relative comfort.
post #20 of 22
Thread Starter 
Since I work in a group setting in a fitness center I don't see my students in their ski boots, nor do I have a way of getting an exact measurement of how much DF they actually have.

However, having been involved with Pilates and dance for # of years, I can get a sense of what is a normal range, aand what is insufficient.

That being said, I do not see myself as someone who is either qualified, or has the desire to take work away from either bootfitters or ski instructors.

So if a student speaks of a problem that may either be a technique or equipment issue, I am quick to reccomend that use a professional with that sort of expertise.

It does get frustrating, though. People will work for hours on their quads, but do nothing to correct what is going on with their feet. Combine that with the issue of both DF and PF reduced with age, it becomes easier to understand some people's technical difficulties with skiing.
post #21 of 22
OK here we go again. LM for the tibialis anterior question, weakness here would certainly encourage some back seat action but I think saying it is responsible for it is just plain mean to a sensitive under appreciated muscle. It certainly comes to play when correcting to neutral from the back seat but it wouldn't have put you there. It also comes to play when resisting forces tossing you around on modern ski gear. I find it tough to train but elite ski racers have gone to efforts to train this muscle for years. Myself I spend a lot of time clipped into pedals working a full stroke on my bike and I think I'm ok there.

Plantar flexion, directly I think it is not very important as it isn't really used. That being said indirectly strength in the gastrocs and soleous is very important both for stabilizing the knee and adjusting balance in varied conditions. It is hard to train those without plantar flexion so indirectly yes important. A solid yes and no.

Burning quads, as I've mentioned in a number of threads and fast man describes as above. Lack of ankle flexion to help maintain a centred position will likely lead ..... well fast man said it. This is also why I often go on about boots with too much forward lean at least for a given lower leg as well as bindings with high ramp angle especially for a smaller boot sole length. Heel lifts to open the ankle joint, high internal ramp angles, straighter standing boots can all help with this problem.

Cement boots, although a person could ski in cement boots the real question is why would you. The difference is skiing well in varied terrain in cement boots. People can ski with fused vertabrae, range limiting knee braces, fused ankles and in fact some can do it well maybe even on some rough terrain. Fact remains it creates challenges and so does poor ankle flexion.

Groomed versus varied terrain, agreed. I didn't bother to respond to the 'what is an expert thread' but I think a lot of that definition boils down to the ability to improvise. Ski from groomed to bumps seamlessly, soft powder to set up avalanche debris, wind polished to wind slab doing all of this is improvisational and practising in this teaches you refined balancing and adjusting skills. Someone (even some of the best racers) cannot always jump into varied conditions and terrain but doing more of it could teach them the skills to make them better racers and better on hard pack as well.
post #22 of 22
Thread Starter 
Quote:
Originally posted by Lisamarie:
Great stuff so far. Now here's an interesting thing, one of the other reasons I asked this question.
This season, anyone who came to my ski fitness classes who complained about constant excessive quad burn while skiing had relatively limited dorsi flexion. Not sure if that's a coincidence or not.
My advice is always to have their boots looked at, and to take a ski lesson, but I found the dorsi flexion quad burn thing interesting.
Quote:
OK here we go again. LM for the tibialis anterior question, weakness here would certainly encourage some back seat action but I think saying it is responsible for it is just plain mean to a sensitive under appreciated muscle.
Did not to be mean and accuse the poor liitle guy, just asking what part it played in the situation. [img]smile.gif[/img] [img]graemlins/angel.gif[/img]
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