TRANSITIONING TO A HIGHER LEVEL OF SKIER PERFORMANCE


The transition to a higher level of skier performance for my spouse and I started in the 2012-13 ski season. After a ten-year hiatus from skiing we were returning to the ski hills with renewed enthusiasm coupled with a desire to reach a higher level of performance. I purchased new narrow waisted skis for both of us. I intended to purchase new ski boots as well. But I quickly backed off from even considering this after assessing a number of new boots as too difficult to work with.

I started The Skier’s Manifesto in the spring of 2013 for a number of reasons. The primary reason was that the forum provided me with an opportunity to acquire new information and increase my knowledge so I could learn how to transition my spouse and I to a higher level of skier performance. The process of attempting to explain complex technical issues by writing articles and posts serves as the impetus for me to think deeply, thoroughly and analytically. As the process unfolded, I discovered issues I had overlooked in the past or not fully explored.

One issue I had not fully explored, let alone addressed, is a way of identifying the optimal ramp angle specific to each skier. Ramp angle is the angle of the ramp of the plantar plane under a skier’s foot with the base plane of the ski. Finding a method of identifying optimal ramp angle proved far more difficult than I had anticipated. But when I succeeded in identifying and then implementing the optimal ramp angles for my spouse and I last ski season this proved to be the gateway to a higher level of skier performance than I could ever have envisioned. After identifying and then confirming my optimal ramp angle as 1.2 degrees (bindings zero) I finally understood after almost 45 years how and why changing from the leather ski boots I learned to ski in to the new plastic boots had such a devastating impact on my skiing. It was the change in ramp angle. The ramp angle in my leather boots was much less than the ramp angle in my plastic boots.

By 1978 I had subjectively found that a ramp angle greater than 3 degrees adversely affects skier performance with some skiers affected more than others. I knew there was no one size fits all, only that more than 3 degrees seemed to cause problems. From 1978 onward I was improving skier performance by ensuring the total ramp angle of the combined boot board/binding (zeppa + delta) was about 3 degrees. For females with small feet this required grinding the boot board in Lange boots flat or even negative (heel down) to compensate for binding ramp angle which increased as the toe and heel pieces moved closer together for small boots. I wasn’t always able to get the ramp angle set at 3 degrees. But getting it in the 3 degree range consistently resulted in significant improvement in skier performance.

It was becoming increasingly apparent to me that finding the optimal individual ramp was critical.

Critical Ramp Angle

In 2018 I identified the critical ramp angle as the angle of the plantar plane in relation to the base plane of the ski that enables a skier to apply maximum vertical force to the ball of the outside foot when the COM in the pelvis is stacked vertically over the head of the first metatarsal.

The vertical force is applied passively by force transfered to the plantar aponeurosis ligament (PA) by Achilles tendon (AT) tension.  As COM moves forward towards the head of the first metatarsal in the support phase where skier resists the force of gravity, AT-PA tension applies an increasingly greater down force to the head of the first metatarsal. Ramp angle is optimal when the vertical force peaks just prior to the end of the support phase in what is called Mid Stance in the Gait Cycle of walking.  I qualified this mechanism as enabling a skier to apply maximum vertical force to the head of the first metatarsal. Studies have shown in the skiing the position of the pelvis in relation to its vertical position with foot is the most reliable indicator of the position of COM. A skier is able to control the vertical force applied to the head of the first metatarsal by controlling the position of the pelvis.

The photos below show Marcel Hirscher and Tesa Worley applying maximum force to the head of the first metatarsal of their outside foot by stacking their pelvis over it.

The Problem with Adapting

The primary determinant of the critical ramp angle is the length of skier’s Achilles tendon (AT).

The length of the AT can and does vary significantly among the general and skier populations. The type of everyday footwear worn and especially what is called drop (heel elevated above the forefoot) can affect the length of Achilles tendon.

Drop affects the timing of the process that stiffens the foot transforming it into a rigid lever for propulsion. Over time, the predominate wearing of footwear with significant drop can cause the AT to shorten as a way for the body to adjust the timing of the stiffening process. In activities such as walking and standing, a shortened Achilles tendon may not have a noticeable affect on performance. But in skiing, the timing of the AT-PA tensioning process is critical. Those who learned to ski in boots with ramp angles close to optimal for the length of their Achilles tendon typically excel at skiing regardless of athletic prowess while gifted athletes who learned to ski in boots with sub optimal ramp angle can struggle in spite of innate athletic ability. For a racer whose equipment is close to their critical ramp angle a change in equipment that significantly changes ramp angle can be fatal to a promising career.

Most skiers would assume that they can just adapt to a sub optimal ramp angle. But adaptation is precisely the reason why skiers and racers with a sub optimal ramp angle reach a threshold from which they cannot advance. When their brain makes repeated attempts to apply force to the head of the first metatarsal without success it starts to make adjustments in what are called synaptic connections to create a new movement pattern to adapt to sub optimal ramp angle. The more the equipment with a sub optimal ramp angle is used the more the associated synaptic connections are strengthened and reinforced. Once the movement pattern associated with sub optimal ramp angle is hardened,  optimal ramp angle is likely to be perceived by the brain as wrong. Telling a racer with sub optimal ramp angle to get forward or get over it (what that means) will only make matters worse because a sub optimal ramp angle makes it impossible. Correcting the ramp angle and/or the length of the AT will not help because neither will change the hard-wired movement pattern in the brain. Deleting a bad movement program can be done. But it usually takes a structured program and a protracted effort.

Mid Stance Misinformation

A factor that I believe may have contributed to the critical ramp angle issue being overlooked is misinformation about mid stance. The story used to sell footbeds and even some orthotics is that skiing is a Mid Stance activity and in Mid Stance the foot is pronated and weak necessitating a foundation under the arch to support it. While it is true that the load phase of skiing occurs in Mid Stance the statement that the foot is weak is only partially true because it doesn’t encompass the whole picture.

The Stance or Support Phase of what is called the Gait Cycle of walking consists of four phases:

  1. Loading Response
  2. Mid Stance
  3. Terminal Stance
  4. Pre-Swing

All four phases happen in a ski turn sequence. The support phase, where one foot is flat on the ground and the leg is supporting the weight of COM, is called Mid Stance. The position of COM in relation to the head of the first metatarsal in Mid Stance and how fast COM can move forward over the head of the first metatarsal (center of the ski) of the outside foot in the load phase is a major factor in dynamic control and the ability of a skier to apply maximum force to head of the first metatarsal. But Mid Stance is a range and a sequential stiffening process, not a fixed point as has been misrepresented for decades by many in the ski industry.

The graphic below shows the relationship of 1. Achilles Tendon Force with 2. Plantar Aponeurosis Force with 3. Vertical GRF and how the tensioning process and transfer of force to the head of the first metatarsal occurs as COM progress forward in the Mid Stance cycle. The timing of the forward advance of COM/Pelvis to sync with peak AT-PA force transfer to the head of the first metatarsal is shown with a red circle and vertical arrow.

If I had only shown the segment of Mid Stance in the grey rectangle at the beginning of Mid Stance on the left I could have made a case that the arch is weak and in need of support since Achilles Tension is zero and Plantar Aponeurosis Force (called strain) is very low. But this would be misinformation because it does not show the whole picture. If the foot were weak as is alleged it would be impossible for it to act in the capacity of a lever in propelling the weight of the body forward in locomotion.

In my next post I will explain how I used NABOSO surface science technology to confirm my optimal ramp angle.

 

8 comments

  1. David, what role does “barefooting” whether actual or virtual(such as wearing zero drop footwear) play in resetting the CNS to or closer to one’s innate, as in before disfunctionating shoe, position? I have been actual when possible and virtual the rest of the time for about ten years and still feel like I am relearning some aspects of walking. Of course I was elevated for sixty plus years so…

    1. I have mentioned a few times that my feet were badly deformed by being put in orthopedically correct shoes when I was a child. It was a big thing back in those days. But by the time I was six I walked with a stagger and couldn’t do sports. I have been working for many years trying to undo the damage.

      Resetting the CNS involves two major things:
      1. Getting the big toe aligned properly with the metatarsals fully spreading and,
      2. Restoring the sensitivity of the nerves in our feet especially the nerves under the ball of the foot and big toe.

      The sensitivity of the small nerves in most people’s feet have degenerated from wearing shoes based on the marketing story that we need cushioning to protect our delicate feet and that feeling anything is a sign that we need more cushioning.

      I do a number of things to help restore foot and nerve function. Most of my shoes are zero drop or close to zero drop with dense soles that compress very little when I walk. With rare exceptions I am barefoot in the home and in most of my shoes, the majority of which are fit with NABOSO insoles. My shoes feel wierd without them.

      If you get some NABOSO insoles and ask your friends to try standing on them and you will probably find out how successfully the footwear industry has been in brainwashing them with cushioning BS story. Most who try NABOSO for the first time will say, “Ooooo, I could never wear those awful things in my shoes. They would hurt my feet. And they don’t support my feet. I don’t get out of bed in the morning without my orthotics. Oh boohoo, poor me. I don’t want to feel anything. I want comfort.

  2. looking forward to read your next post, I’m also struggling with my ramp angle (and my femur internal rotation) Thanks!!

    1. I am more than happy to provide you with as much knowledge detail as I know on this issue and the associated factors if you and others who are reading this will test my knowledge by putting it into practice and providing me with your feedback.

      That much of what I have learned since 1980 still does not appear in the literature is both perplexing and disturbing to me. What process led the ski industry to conclude that elite skiers can ‘somehow balance’ on their outside ski so there is no need to invest time in iliciting the underlying mechanics, neurobiomechanics and physics. Ramp angle is the same. Through what process did the ski industry conclude that ramp angle is a non-issue? Please work with me. I could use some help.

      1. Thanks again. A bootfitter set in my boot soles lifters with a 1.5 and 2 degrees outwards to improve my alignment, i’m kind of a “A frame” guy but i’m not sure if it helps. Also Paul Lorenz says he’s got 8mm in his heels … and I’m thinking about it too. Too many issues though hehe!

      2. Improve your alignment in relation to what. Is your boot-fitter implying that when you walk or run your cns can’t get your foot in the right place so you come into balance on it? I am not aware of an explanation based on principles of applied science let alone any studies that would show how placing lifters or cants on boot soles would have a positive benefit for the function of the lower limbs. Configuring the shaft of the boot is very important. But that is not the same as using wedges as advocated by many. When the plastic boots were introduced it was not possible to adjust the shaft. So canting was the only option for leg with a varus or valgus angle that didn’t match the boot shaft. In the order of things stance training that configures the major muscles in isometric contraction and tensions the fascia comes first followed by identifying the optimal ramp angle then implementing it with what I call a monoplanar (flat in xy planes) boot board. Although there appears to be a generic ramp angle of about 2.3 – 2.5 degrees that is workable for most (workable, not optimal) it will not work if one is an outlier. This also assumes bindings at zero since binding ramp (delta) affects boot forward lean as well AND stand height.

        The reason I am in the process of winding down my blog is that I am not seeing any signs that the ski industry intends to address issues like ramp angle for which there is presently no consistency let alone any standard.

    1. I think you are on the same page as I am. The problem with the term neutral stance is that neutral is a nebulous term in the narrative of skiing that can mean anything the person using it thinks it means. That’s why I a point of defining what I mean by a term such as ‘balance’ which like neutral can mean anything the person using it thinks it means.

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