IT’S A MATTER 0F BALANCE


Few would dispute the position that balance is everything in skiing. It is probably widely assumed that in most, if not all sports, the most highly trained athletes, especially those at the highest level,  have the best balance. It is also probably assumed that this would be especially true of the best racers at the World Cup level of competition. However, a paper published in the British Journal of Sports Medicine states, “……few studies have analysed subjects’ postural performance in order to discriminate the expertise level among highly skilled athletes of a specific discipline and results remain controversial…….. no study has been carried out to evaluate postural control in alpine skiers”.

Is postural control affected by expertise in alpine skiing? (F Noe ́, T Paillard: Br J Sports Med 2005;39:835–837. doi: 10.1136/bjsm.2005.018127)

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1725069/pdf/v039p00835.pdf

I have long been critical of the claims made or implied that securing the foot and lower leg in what amounts to an orthopaedic brace or splint is a good thing. My US patent 5,265,350 (November 30, 1993) states:

“Existing footwear does not provide for the dynamic nature of the architecture of the foot by providing a fit system with dynamic and predictable qualities to substantially match those of the foot and lower leg. The stated position of various authorities skilled in the art of the design and fabrication of footwear for skiing is that the foot functions best when movement about its articulations is substantially prevented or restricted. Existing footwear does not adequately anticipate this re-alignment of the architecture of the foot and thus such footwear inhibits the wearer’s ability to assume a balanced position.

In other words, conventional ski boots make balance more difficult for the skier. My position was based sound principles of functional anatomy and studies of human balance and movement performed in laboratory settings. But until the recent study by Noe ́and Paillard, the impact of the conventional ski boot on skier balance had never been studied. For Noe ́and Paillards’ study, fourteen healthy male competition skiers voluntarily participated. They were divided into two groups. The first group consisted of seven regional level skiers. The second group consisted of seven national/international level skiers either in the French junior national team or in the French senior reserve national team. Candidates with balance disorders were excluded from the study. A number of different balance tests were performed including tests done on a force platform and on a seesaw device that generated instability. Tests were done with and without shoes and while wearing ski boots. Foot pressure data captured sway patterns associated with balance.

RESULTS

The analysis revealed no significant group effect in the AP (front to back sway) posture. But the analysis found significant differences in the STA (stable) and ML (side to side) postures. The Centre of Pressure excursions (a reliable indicator of balance), were significantly greater for NAT skiers compared to REG skiers as in worse for NAT skiers.

“The results obtained in the REF condition are not in agreement with previous studies concerning expertise in sport and postural ability since they illustrate reduced postural performance as the level of competition increases (my emphasis added). However, the results can be explained by considering the specificity of alpine skiing, which involves the necessary use of ski boots over most of the training period. As Schaff and Hauser demonstrated, very stiff ski boots as used by competition skiers act as an external ankle support which mechanically restricts ankle joint motion. The effects of such ankle immobilisation are similar to those induced by ankle braces, and it is known that restriction of ankle movement has a significant detrimental effect on postural control (my emphasis added). Hence, the inferior postural performance observed with NAT skiers in the REF condition may illustrate a long term effect of repetitive wearing of ski boots, which impairs postural performance by restricting the range of motion of the ankle-foot complex. REG skiers may be less affected by this long term effect since they spend less time training.

“The present study shows that skiers at the highest level of competition presented inferior postural performance compared to lower level skiers when standing without ski boots. This result illustrates a long term effect of repetitive wearing of ski boots which impairs the postural performance of high level skiers.”

There will no doubt be some who will challenge the conclusions of Noe ́and Paillards’ study. To them I say, “show me your studies”.

14 comments

  1. What you are talking about is applying pressure to a certain spot and letting the bodies’ natural ability to balance align against that point. What I was doing was trying to get to that balance point with a lot of conscious ankle action to initiate the turn but your explanation tells me that as I suspected, you are being more patient. Once I get on the snow I’ll be able to quickly determine how close I am to your explanation vs. what I had developed over the years. I already know your idea works because it helps me run pain free after 30-40 years of not running at all. It is a more subtle focus than my previous one of rolling the foot/ankle so I’m all for that because it’s more accurate. Moving the focal point from my knees to my feet in the past tremendously improved my ability to stay in balance because it is more subtle so if I can ski by twitching my pinky toes, that’s what I’ll do!! Of course. the first thing I had to do to make the change was get the ability to move my feet in the ski boots!! Also I need to qualify patience, don’t anybody think that doesn’t mean you can’t make quick turns because I see Mikaela Shiffrin as being very patient!!

    1. I am in the process of writing a post on this now. About 30 years ago I discovered that good skiers apply pressure on two distinct areas under the outside foot; the ball of the big toe and under the heel. Very few skiers are aware of this. They either feel high pressure under the ball of the foot or the heel. If they feel pressure under the heel, there is very little pressure on the ball of the foot. But when there is high pressure under the ball of the foot, there is much less under the heel. This creates a pressure a diagonal bias towards the ball of the foot that is at about a 15 degree variance with the transverse center of the ski and the foot anatomic center of the foot. On a narrow waisted ski (63 to 65 mm in minimum profile width) the diagonal bias line passes through the ball of the foot, crosses the inside edge and runs inside the shovel. It crosses the outside edge behind the heel. This creates a much higher pressure on the inside edge compared to the outside edge. What effect do you think this has on the ski? When I raised this issue with high level coaches 30 years ago, it was summarily dismissed as ‘nothing’. In fact, it is everything on skiing. It is the secret of the world’s best skiers.

      1. Yes, I agree with this, and this is why I wrote about the eccentric boot cants. I didn’t suggest that the boot upper rotated, rather that it flexed in the proper direction. I ski the Atomic RT Ti 150 and I can get them to flex a bit. I am not trying to flex them with a down motion, and definitely not with a pure forward motion but rather by driving my lower legs in the direction of the turn using my glutes and abdominal muscles (roughly, my center of mass). If my set up is correct, I can move from the heel to the ball of my foot.
        Because I seem to have many “suspension” problems, my set up has to be almost perfect. I have to tweak the adjusters every day I ski. I find that if my boot bladder is slightly twisted, or the tongue isn’t in exactly the right place, this affects the adjustment.
        Where can I get plans/drawings of the Roll Over trainer?

      2. I am in the process of writing a post that I hope will clarify the issues. There is so much noise and static created by erroneous information embedded in narratives on ski technique, much of which is nothing more than uninformed ‘opinion’, that it is difficult for skiers to see the real issues. One of the key issues is the centres of the two primary forces under the foot. When the force or pressure from the load of the body is sensed under the heel, there is very little force on the forefoot and the load axis is towards the outboard aspect of the center of the outside ski. The only way that the center of force or Center of Pressure can be moved to the ball of the foot is when the ski is flat on the snow between edge change at the end of the transition or when an airborne skier lands flat on the outside ski in the fall line.

        What everyone seems to have missed is that when the Centre of Pressure is under the ball of the foot, there is always a secondary Center of Pressure under the heel. The reason it is not felt is that it is much lower in pressure than the Center of Pressure under the ball of the foot. There is what amounts to a structural bridge between the Centres of Pressure under the heel and ball of the foot running about 15 degrees diagonally across the ski. It runs through the ball of the foot, emerges inside the shovel and exits behind the heel where it crosses he outside edge towards the tail of the ski. Good skiers don’t drive the lower leg in the direction of the turn. They push the ball of the foot down into the snow while rotating the outside leg so that it rotates the ball of the foot into the turn from a center under the base of the tibia. The ability to apply these forces requires a chain of muscles in eccentric contraction that tension the pelvis from above and below. In other words, stance is the key and it must be learned and rehearsed. In a high load GS turn, recreational skiers using this stance can easily apply forces of 3 or 4 Gs under the ball of their outside foot. How many Gs do you think Ligety or Shiffrin applies? Lots.

  2. Have you considered the negative effect that many ski boots have in flexing parallel to the long axis of the ski/foot?
    In order for my feet to pronate, my boot cuffs must track inward, matching the Natural Plane of Flex of my ankles.
    The first boots that allowed this for me were Kolflachs (patent transferred to Atomic when company sold) with their double eccentric cant adjusters.
    Boots that track straight ahead cause my feet to experience inversion and finally rotation of my legs outward.
    Not good for alpine skiing, cross country skiing, skating or even walking.
    I modify my rollerblades, alpine, cross country and hiking boots to allow my lower legs to track inward.
    When my feet start to roll outward, I know my ankle flexing at that point will cease.
    This is probably why so many people are unable to bend their ankles and are stuck in the back seat.
    I base this on my 29 years of full time ski instruction and the success my students had working with a boot fitter who didn’t try to create giant arches where none were needed.
    The only problem I have is I need more positive “boot cuff cant” on my right leg than the standard eccentrics provide, so I remount the eccentric’s pivots.

    1. By the natural plane of your ankle, you seem to be inferring that the cuff of the boot must rotate internally in order for your foot to pronate and that boots that flex straight ahead will prevent this. I discussed this issue in detail in my US Patent 5,265,350. Internal rotation of the leg relative to the foot through the subtalar joint does not affect the functional axis of the ankle complex. If this did happen, we would not be able to walk or run. What is referred to as dorsiflexion is a cooperative effort of the tibial-talar and subtalar joints. This is discussed in detail in The joints of the Ankle by Verne T. Inman published in 1967.

      A significant issue is the morphology or physical structure of the foot and leg and especially how tightly the closures of the boot are secured. Good natural skiers tend to have skinny legs and feet that are tight, compact and moderate in width. This allows rotation of the leg and about 10 degrees of free flexion to occur with the fixed dimensions of the shaft of a ski boot provided the closures are correctly adjusted. The key is setting up the shaft of the boot to allow a skier to stand in the boot with what I call the reference shank angle. This shank angle is relatively fixed from the start to end of turns made by elite skiers and racers. The perception that the shaft of race boots flexes suggested by the presence of what appears to be hinge rivets or screws is an illusion. The shaft is fixed in position to the shell lower with not rotation possible. If you are trying to flex your boots in a turn, the center of pressure under your outside foot will shift under the heel bone, away from the inside edge and outboard of the transverse center of the ski. The resulting moment arm and moment of force will cause your foot to invert.

  3. So, moral of the story is to go barefoot on uneven ground whenever possible? I have an old friend in Chamonix who skis hard and goes barefoot even in the winter. His feet are so ugly… It is amazing he can get them into ski boots! But his spirit and joie de vivre… magnifique!

    1. Going barefoot and doing foot exercises like the short foot will definitely help skiing but only if the foot has 3-dimensional space for the joint actions necessary for skiing. The problem is that ski boots and interventions such as custom liners and insoles, intentionally obstruct and impede the necessary joint actions which are required for the coordinated muscle activity responsible for balance. Worse, such interference loads the joints horizontally and, in so doing, introduces foreign forces to mechanoreceptors that are out of phase with the neural flow responsible for balance. In the name of trying to keep things simple, the ski industry has made skiing far more complicated for the balance system that it needs to be to the point where it appears to be having a detrimental effect on the normal processes of balance.

  4. Finally built a Roll Over Trainer and learned a couple of things in the process. First, I mentally made it more difficult than it really is before I even started so second, maybe the reason so many people are resistant to change (your unique perspective) is because somehow it is ingrained into us that everything is too complicated to be done, someone else has to do it for us. That leads to a question, do you worry about adjusting the resistance to the ‘trainer’ tipping as the weight is shifted or let the body control that? I can definitely feel the shift of weight to the first met and haven’t played around enough with ‘ramp’ etc. as yet to see the differences. Also with no snow it’s hard to tell if this will transfer readily to my skiing or not. When I first got into my ski boots (I felt were well adjusted for me at the end of last season) I noticed the pressure right away at the first met. Then I realized that was because both feet were in line which wouldn’t be the case if I was turning on skis, so moving my unweighted foot back immediately moved the pressure off of first met and onto the heel. I also realize that is definitely the contact point I strive to feel when I place my feet down walking and running these days. Definitely is interefered with by any foot wear with too high of a heel.

    1. “That leads to a question, do you worry about adjusting the resistance to the ‘trainer’ tipping as the weight is shifted or let the body control that? I can definitely feel the shift of weight to the first met and haven’t played around enough with ‘ramp’ etc. as yet to see the differences.”

      The objective of the Trainer is to train skiers and racers to maximize the load or pressure differential between the heel and ball of the foot and reorient the load/balance axis of the foot so it is aligned diagonally across the long axis of the ski instead of parallel to it. Since the load applied to the ski is rarely, if ever mentioned, in discussions of the forces of skiing or show in force diagrams, you probably have no idea what I am talking about. I am working on some graphics to help explain these effects in a future post. I am also working on some exercises for the trainer. For now, once you can instigate tipping by allowing the foot to pronate to load the ball of the foot sufficiently cause the plate to tip towards the inside edge, try shifting the plate away from the edge a few mm until it takes a higher load on the ball of the foot to instigate tipping. Make sure the plate is kept parallel to the pedestal it is mounted on. It is also important to allow the foot to pronate and not cause it to pronate with conscious muscle activity using the everter muscles. The load of COM must cause pronation/ball of foot loading that stretches the inverter muscles in eccentric contraction.

      1. Excellent explanation. I should have started a new paragraph because the business about the “other’ factors had nothing to do with the training of creating the correct pressure. Since I can’t take this to snow right now I’m curious if that is always the position of the ankle and foot balanced against the ski or do you ever consciously change the angle between the lower leg and foot at the ankle joint? That was what I’ve been doing for years but realize that my industry standard alignment forced me to be locked in a bowlegged position so I had to do every thing imaginable to even get to the inside edge much less balance there!! Now with fantastic mobility within the boot I already have questioned if I need to articulate at the ankle this much knowing it’s an old habit of previous necessity.

        The rest that I talked about is I’d just to seeing if using the trainer can help with determining some of other aspects dealt (or not!) with in boot fitting such as ramp angle etc. Just wanted to keep you updated on how I’m torturing your trainer!!

      2. “Since I can’t take this to snow right now I’m curious if that is always the position of the ankle and foot balanced against the ski or do you ever consciously change the angle between the lower leg and foot at the ankle joint?”

        I’m not sure what you mean by “consciously change the angle between the lower leg and foot”. The feeling I want to acquire at ski flat at the end of the transition is one of a disk about 1.5 inches in diameter under the ball of my foot that I am applying pressure to. As I extend my outside leg I am applying rotational force from the pelvis so my skis turn into the fall line. I need to stay compact to ensure that I do not fully extend until I am in the fall line so I can keep the pressure on the disk under the ball of my foot. The real action starts when I rotate my outside ski across my line down the fall line. Gravity is causing me to accelerate. So when my outside ski crosses my line and acquires edge lock, I run into my ski. The force of gravity causes the shovel to ‘hook’ across my line. The load on the disk at this point in a high speed GS turn is 3 to 4 Gs. I call this a ‘comma hook’ turn because it looks like the hook on the bottom of comma. I never consciously try to change any alignment. My CNS takes care of this at 11 million bits per second compared to 50 to 60 bits per second at a conscious level.

  5. This is interesting stuff, which I can relate to. I have clamped my feet into very tight ski boots for instructing and masters racing for a good part of 47 winters. My static balance on one foot is terrible. I know this isn’t necessarily a cause and effect situation, other factors may be at play, but it is an interesting theory. On skis my dynamic balance is fine, I can ski on one ski with little difficulty. I went for physiotherapy a couple of years ago and the physio couldn’t believe I could possibly be a ski racer given my poor balance. After following your blog I have started to modify the liners in my ski boots; cut the front off my older Nordica Dobermanns and opened up the toe box on my Head Raptors. I’m liking the results, allowing me to ski more with my ankles and more flexed and balanced generally. Thank you for that.

    1. When I start posting on my work with local ski pro, Matt Williams, I will include photos showing what I had to do to his liners so he could ski properly. Expanding the shells to create sufficient width for his forefoot and space for his inside ankle and the navicular bone below and in front of the ankle was not, in itself, enough. I still had to remove all the padding on either side of the liner and then cut away the entire front portion. I did this with one boot at a time with Matt so he could use the unmodified boot as a reference. This protocol is much more telling and convincing than changing everything at once. I keep a running message dialogue going with Matt so I have a record of what is happening. Here are some of Matts’ text message comments.

      MATT: “I felt a new found freedom in being able to do a carved turn or a skidded turn or anything in between… When I’m on the front of the foot and turning the leg against my body… The ski does exactly what I’m trying to get it to do after ski flat…….. the boots are skiing great and I feel better by the day.”

      “……..I took my footbeds out at lunch because i felt like they were getting in the way”.

      COMMENT: Matt is referring to the stock Head insoles that I heated pressed flat in a vice and not the custom molded footbed which he can no longer use because of interference with the dynamics of his arch. As he gets better at loading the ball of his outside foot, the tension in his arch becomes increasingly higher to the point where it can and did start to apply pressure to any structure that is even slightly raised. In this case, the inner edge of the insole was still rolled up slightly. It was not much, but it was enough to cause problems. Matt’s experience is typical.

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