World Cup Ski Technique posts

WILL SKIING SURVIVE?

In an October 1997 Skiing Trade News article Jerry Groswold, a ski area consultant and former president of Winter Park Park Resort, talked about the message in a presentation by former Dallas Cowboy quarterback Roger Staubach. Staubach’s presentation was to a non-ski audience. But Groswold saw how it applied to the situation emerging in the ski industry. 

Staubach spoke about gatherers and sharers. He characterized gatherers as those who take for themselves and sharers as those who work for the common good. Staubach expressed concerns about those gatherers whom he referred to as “destructive achievers”; those who, for whatever reason, feel compelled to acquire at all cost. Groswold expressed the fear that the impact of “destructive achievers” was starting to be seen in the ski industry.

More than 20 years ago Groswold saw the ski industry standing at a crossroad. He cautioned that too many people had worked too long and hard to build the sport to allow it to fall prey to Staubachs’ “destructive achievers”. Groswold warned that only by remembering its roots – that skiing is a sport first, a passion second and a business third – will skiing succeed. 

A new Youtube video (1.), Why ski resorts are dying – Cheddar explains, paints a picture that suggests Groswolds fears are coming to pass.

Skiing is the quintessential winter pastime. But recently, the multi-billion dollar industry is in decline. The number of skiers is falling fast and the industry is scrambling to make up the difference. Is this going to be the end of the ski resort?

When I started skiing in 1970 the sport was entering a period of vigorous growth. The introduction of the safety release binding followed by the rigid plastic ski boot that promised to give every skier the edge, had begun to attract gatherers who saw an opportunity to profit from the next big thing. The ability to mass market the Perfect Fit that the rigid ski boot made possible was the Perfect Marketing Story. With ski boots that were individually Perfectly Fit to every skier any problems with ski technique could be claimed to be a skier problem requiring lessons.  There is no reason for a gatherer to question, let alone critically examine, the Perfect Fit story. There is even less reason for a gatherer to invest in research to find ways to make skiing easier. That the Perfect Fit story sells product and services appears to be the only thing that matters.

Those who have been able to apply some of the concepts described in my blog have found that skiing can be as easy and intuitive as walking. 

The Birdcage research vehicle that resulted out of more ten years of effort on my part whose principles were validated with on-snow studies done in 1992 had the potential to make skiing as easy and intuitive as walking. Today, the refinement of the Perfect Fit has made ski boots all but impossible to sufficiently modify to accommodate end user function.

Whether skiing survives depends on whether skiers will retake their sport from the gatherers.


  1. https://youtu.be/AVSjsYHX6eM

For his immense contributions to the sport,Groswold was enshrined in the U.S. Ski & Snowboard Hall of Fame in 1986, the Colorado Ski & Snowboard Hall of Fame in 1987, the Colorado Ski Business Hall of Fame in 2005 and received countless other awards. 

CHANGES COMING T0 THE MANIFESTO

In a few days, my blog will start to include advertisements. The reason for this is that I have decided to take a break and not renew my subscription for the premium plan that eliminates advertisements. The blog will continue to exist. At some point I may renew my subscription to the  premium plan.

The most important posts I have ever published are the series on The Mechanics Patform Angle and The Future of the Ski Boot Parts 1 and 2. For reasons that aren’t clear to me the ski industry has never done a comprehensive analysis of the forces acting between the outside ski and snow that create a platform that skiers can stand and balance on. Instead a simplistic and incomplete explanation was put forth that viewed balance in terms of opposing vertical forces missing the most important forces, horizontal forces into the hill parallel to the base of the outside ski and multi-plane torques. Unfortunately this seriously flawed explanation gained wide acceptance.

The ski industry also failed to recognize that FIT equates with DYSFUNCTION especially impaired neuromuscular function. I went into detail in this in Part 2 of The Future of the Ski Boot.

The forces associated with The Mechanics Patform Angle are not simple. They are all described in my posts for those willing to invest the time and effort to gain an understanding. But there is no shortcut. Either you understand all aspects or you understand nothing.

Skiing can and should be as easy and intuitive as walking. That it isn’t is the failure of the ski industry,not the failure of the skier.

THE FUTURE OF THE SKI BOOT – PART 2

The introduction of the rigid shell ski boot served as a foundation for the evolution of what became a science of immobilization and splinting of the joints of the foot and a leg of a skier. By creating an encasement for the foot and the portion of the leg within the rigid shell, mediums such as foam could transfer force to the ankle and leg to substantially immobilize its joints. Supporting the foot in a neutral position with a rigid footbed or orthotic in conjunction with form fitting mediums ensures maximal immobilization that is described as the Perfect Fit. The science of immobilization has evolved over the years to include thermoformable liners and even thermoformable shells.

Even though the medical textbook, The Shoe in Sport, cautioned 30 years ago that “the total immobilization by foam injection or compression by tight buckles are unphysiologic (against physiologic function)” the proponents of immobilizing the joints of the ankle continue to claim that this puts the foot in it’s strongest position for skiing.

The paper, Recent Kinematic and Kinetic Advances in Olympic Alpine Skiing: Pyeongchang and Beyond,  published on February 20, 2019, cited better transfer of the skier’s action to the skis through improved boot-fittings with individual liners and insoles. If in fact, skier performance is improved due to improvements in the science of immobilization through boot-fitting then it should be evident in studies that look at skier performance.

One such study, Challenges of talent development in alpine ski racing: a narrative review, published in March of 2019 found:

Youth and adolescent ski racers report lower injury rates compared to World Cup athletes. The knee was the most affected body part in relation to traumatic injuries. The most frequently reported overuse injuries were knee pain (youth) and low back pain (adolescent level). Athlete-related modifiable risk factors were core strength, neuromuscular control, leg extension strength and limb asymmetries.

Neuromuscular Function (NMF) affects Neuromuscular control (NMC). NMC is an unconscious trained response of a muscle to a signal associated with dynamic joint stability. This system of sensory messages (sometimes referred to as “muscle memory”) is a complex interacting system connecting different aspects of muscle actions (static, dynamic, reactive), muscle contractions, coordination, stabilization, body posture and balance. The movements of the lower extremity, including the knee joint, are controlled through this system, which needs correct sensory information for accurate sequential coordination of controlled movement.

It has been known for decades that restricting the action of a joint or joint system, especially immobilizing the joint, will cause the associated muscles to atrophy. But a study, Effect of Immobilisation on Neuromuscular Function In Vivo in Humans: A Systematic Review, published in March 2019, suggests that the effects of immobilizing joints of the body are far greater than simply causing muscles to atrophy. This is the first systematic review to consider the contribution of both muscle atrophy and deterioration in neuromuscular function (NMF) to the loss of isometric muscle strength following immobilisation. The fact that the study, Challenges of talent development in alpine ski racing: a narrative review, cited core strength and neuromuscular control as issues in the development of talent is significant. The feet are part of the core in what is called foot to core sequencing. Immobilizing the joints of the foot can affect lower limb and core strength.

Immobilisation in the study the Effect of Immobilisation on Neuromuscular Function In Vivo in Humans: A Systematic Review, was achieved by using casts, braces, slings, unilateral suspension, strapping or splints with the following locations immobilised: knee, ankle, wrist and finger. All studies measured isometric muscle strength. No studies were cited that involved bilateral immobilisation of both ankles such as occurs in form-fitting ski boots. However studies did find that multiple joint immobilisation was likely to produce the largest change in the NMF of segments consisting of both mono and biarticular muscles. Other key findings were:

  • The greatest changes in all variables occur in the earliest stages of immobilisation.
  • The loss in muscle strength during immobilisation is typically greater and occurs faster compared to the loss of muscle volume.
  • The choice of joint angle for immobilisation using the brace or cast method appears likely to play a large role in the outcomes.

I started this blog six years ago for several reasons. A primary reason was to identify whether any influences existed in skiing that would serve to change the focus from immobilizing the joints of the foot and leg with the associated claims to a science-based focus. Since the future of the ski boot appears to be continued refinement of the science of immobilization this will be my final post.

I have learned a lot over the past six years that led to huge breakthroughs on skis for myself and those who I have worked with. Thank you to those who commented and contributed to The Skier’s Manifesto.

FOOTBEDS: THE UNKNOWN COST OF SUPPORTING THE ARCH OF A SKIER’S FOOT

Two recent studies (1.), (2.) question the merits of supporting the arch of a skier’s foot and especially any claims made that supporting the arch in neutral is the strongest position for skiing. 

It is well established in the scientific literature that the plantar aponeurosis (aka plantar fascia or PA) is one of the major arch-supporting structures of the human foot.  A positive correlation between Achilles tendon loading (ATF) and plantar fascia tension (PAF) has been reported. A study (3.) found that plantar aponeurosis forces (PAF) gradually increased during mid stance and peaked in late mid stance. The study found a good correlation between plantar aponeurosis tension (APF) and Achilles tendon force (ATF). The study concluded:

The plantar aponeurosis transmits large forces between the hindfoot and forefoot during the (mid) stance  phase of gait. The varying pattern of plantar aponeurosis force (PAF) and its relationship to Achilles tendon force (ATF) demonstrates the importance of analyzing the function of the plantar aponeurosis throughout the stance phase of the gait cycle rather than in a static standing position. – (my emphasis added in bold)

I discussed this in my post TRANSITIONING TO A HIGHER LEVEL OF SKIER PERFORMANCE.

The graphic below from Kevin Kirby’s Foot and Lower Extremity Biomechanics II:  Precision Intricast Newsletters, 1997-2002 illustrates how the position of COM in relation to the foot tensions the GS (gastroc-Soleus) compressing the arch which tensions the plantar aponeurosis ligament. I have added arrows to indicate PA strain Force F and Shear Force as well as Arch Compression Force.

The graphic below also from Kevin Kirby’s Foot and Lower Extremity Biomechanics II:  Precision Intricast Newsletters, 1997-2002 illustrates how the anterior (forward) advance of CoM in relation to the foot decreases rear foot loading (GRF-RF) and increases fore foot loading (GRF-FF). I have added a red dashed vertical line and a red triangle to show the approximate location of what would be what I term the tipping or pivot point where the foot would rock rearward and forward with a corresponding shift in CoM.

The two recent studies I referred to (1.), (2.) that question the merits of supporting the arch of a skier’s foot were actually done with subjects walking and running on flat and inclined surfaces. But the effect on arch compression is applicable to the effect of arch supports used in ski boots.

New Balance Minimus road MR00 shoes were provided to all participants to wear for testing (approx. weight 180 grams, zero heel-toe drop, no medial arch support and a uniform EVA midsole). Pockets filled with lead weights were affixed to the laces of both shoes in order to standardize foot weight across all shoe and insole conditions. The minimal shoe was chosen as a control condition in order to standardize non-insole effects as much as possible.

Two separate custom insoles were designed for each participant and fabricated by orthotic laboratory. The first insole was designed to restrict arch compression near-maximally compared to that during shod (barefoot) running (Full Arch Insole; FAI). The second insole was designed to restrict compression by approximately 50% during stance (Half Arch Insole; HAI). TO qualify for the study participants could not wear orthotics on a regular basis.

The study found:

The insert restricted maximum arch compression by approximately 70% when compared to unrestricted shod running and consequentially resulted in lower strain values throughout the entire stance phase. It should be noted that the PLF length only surpasses the estimated resting length between ~25%-80% of the stance phase in the insert condition (Fig 3). The negative strain values should be regarded as a slack PLF length, not as the PLF shortening beyond the resting length. 

The graphic below from the paper The Foot’s Arch and the Energetics of Human Locomotion shows the maximum arch compression of subjects shod barefoot (Shoe-only), with the Half Insole that restricted arch compression to 50% of the maximum amount and with the Full Insole that maximally restricted arch compression. The Full Insole is typical of insoles used to support the arch of a skiers’ foot.

 

The insoles had no effect on the metabolic cost of walking despite restricting ~80% of arch compression. 

In a personal communication with Sarah Stearne she advised me that the study didn’t measure muscle EMG activation with and without the insole but they did know that the ankle performed less positive (-8%) and negative (-10%) mechanical work when the insole was worn and that the ankle peak dorsiflexion moment was reduced (-7%). Based on the ankle moment and Achilles tendon moment arm data they calculated that there was ~6% less force in the Achilles tendon when the insole was worn.

Whilst several studies have acknowledged the elastic energy storage potential of the PLF, this ligament is primarily regarded for its role in providing integrity to the bony arch structure, and in supplying the rigidity required for the foot to function as a lever during propulsion (or skiing, my comment) 

This study confirms what I experienced in 1973 after I had full support custom orthotics made by a well known sports podiatrist. The orthotics felt comfortable standing on them and even walking. I experienced some discomfort when attempting to run with the orthotics in my jogging shoes. But when I tried skiing with them in my ski boots I felt as if my foot were floating on the top of the orthotic with little or no sensation of any force under my first MPJ.

Based on the results of two cited studies I believe there is no basis to assume that supporting the arch of a skier’s feet will have positive benefits or is without adverse consequences without first conducting comparative studies using standardized controlls (no insole, flat boot board) and established scientific protocols.


  1. The Foot’s Arch and the Energetics of Human Locomotion – Sarah M. Stearne1, Kirsty A. McDonald1, Jacqueline A. Alderson1, Ian North2, Charles E. Oxnard3 & Jonas Rubenson1,4 – (January 19, 2016)
  2. The Role of Arch Compression and Metatarsophalangeal Joint Dynamics in Modulating Plantar Fascia Strain in Running – Kirsty A. McDonald1, Sarah M. Stearne1, Jacqueline A. Alderson1, Ian North2, Neville J. Pires1, Jonas Rubenson1,3* – (April 7, 2016)
  3. Dynamic loading of the plantar aponeurosis in walking – Erdemir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA

NABOSO: FEEL THE FORCE

To Dr. Emily Splichal

In recognition of Dr. Emily Splichal’s contribution to my knowledge and through the knowledge gleaned from the use or her pioneering NABOSO surface science technology I am dedicating this post to her as my teacher, mentor and inspiration. Thank you Dr. Splichal.


In this post I am going to discuss how NABOSO surface science technology gave me the feedback mechanism to confirm the optimal ramp angle I needed to transition to a higher level of skier performance.

Optimal Ramp Angles starts with Stance Training

My transition started with refinements to my stance that came from incorporating Dr. Splichal’s principles of foot-to-core sequencing (that connects the feet with the pelvic core) and body fascial tensioning (that unifies the body). Prior to these changes my stance is what I would now define as good but not optimal. The huge improvement resulting from the refinements served as the impetus for a series of posts on the sequencing process required to assume a fascially tensioned stance with foot to core sequencing. I called this the SR Stance. The reason I chose this name was to draw reader attention to the stance posts by making the stance seem innovative, but not intimidating.

KIS is the Stance Kiss of Death

In reviewing material on ski technique, a skier’s stance is described as anything from an athletic stance, a relaxed stance, a ready stance, a balanced stance, a centered stance or a whatever feels good stance. A focus on selling skiing as easy with the KIS principle (Keep It Simple) has resulted in stance being perceived as less than critical to good technique. This leaves most skiers with the impression that a ski stance should feel similar to a relaxed upright stance on two feet with weight equally distributed between both feet and the heels and forefoot of each foot. This is interpreted by skiers as meaning they are balanced or in balance. So it follows that in actual skiing there should be even ‘pressure’ everywhere with no sensation of pressure on any specific area of the foot.

If I ask a typical skier to stand on a ramped surface and assume their ski stance they will find the sweet spot where their weight feels evenly distributed and identify it with their ski stance regardless of the  angle of the surface

So the first challenge to transitioning to a higher level of skier peformance is accepting that a strong ski stance must be learned and consistently rehearsed by doing drills as I do every time I go skiing. It’s like pre-flight check. NABOSO provide the conscious and subconscious CNS feedback that tells me when I am cleared for take off.

The NABOSO Effect

In my post NABOSO PROPRIOCEPTIVE STIMULATION INSOLES, I stated that the principle proprioceptive neural activity associated with balance responses occurs across the plantar plane. It is strongest in the 1st MPJ (big toe joint) and big toe. The fast acting small FA II nerves in this area are activated by pressure and skin stretch both of which occur in the late phase of Mid Stance. Optimal ramp angle is critical because it maximizes both pressure and skin stretch thereby potentiating the sensory input required to initiate controlled movement.

Assuming a NABOSO is trimmed, if necessary, to fit a shoe, there will be a positive effect on plantar proprioceptive stimulation. But my experience to date has been that the plantar proprioceptive stimulation will be much more pronounced in a minimal, zero drop shoe with adequate width for fascial forefoot tensioning and correct alignment of the big toe.

The big breakthrough for me came after I started using NABOSO insoles in shoes with different heel raises (drops). It turned out that I had the highest perception of  pressure under the ball of my foot in late mid stance phase with shoes with zero ramp (drop). When I put NABOSO insoles in my ski boots to test them I could hardly perceive any pressure under the ball of my outside foot during skiing no matter how I adjusted my stance or the tensions in my boot closures. This told me that my ramp angle of almost 3 degrees was far too great. As soon as I reduced the angle to 1.2 degrees (which is what I tested best at on my dynamic ramp angle device) it is no exaggeration to state the the whole world changed. But the transition effect didn’t kick into high gear until this ski season after my brain had time to delete a lot of the bad programming from the old ramp angle.

NABOSO 1.0 on the left. NABOSO 1.5 on the right. I use 1.5 in my ski boots. I purchase the large size and trim to fit.

Tentative Conclusions

  • A system that provides continuous subconscious sensory input to the CNS with the ability to consciously sense sensory input during drills in executive mode is important.
  • Stance training should be incorporated into racer training programs at an early stage and optimal stance ramp angle identified and implemented.
  • Once optimal ramp angle has been implemented the boot should be set up to the skier’s functional specification which I will discuss in future posts.
  • Stance ramp angle should be retested on a periodic basis to confirm the requirements have not changed.
  • Adjustments should be made as soon as possible after the end of a competitive season and no further changes made during the subsequent competitive season.

In my next post I will discuss Dr. Splichal’s protocol for using NABOSO insoles and matts in training.


Disclosure

I am not involved in any form of business association or affiliation or any have business interest or investment with Dr. Splichal/NABOSO/EBFA. Nor do I receive any form of compensation from the sale of NABOSO. Prior to marketing her NABOSO insoles Dr. Splichal provided me with a small sample of NABOSO material at her cost to cut insoles from for testing.

 

 

THE ULTIMATE LOOSE FOOT TEST OF METAL

The human foot is a masterpiece of engineering and a work of art.

                                                                                                                  Leonardo da Vinci

Despite what da Vinci said, skiers seem to have an inherent distrust in the structural capacity and integrity of the human foot.

In skiing demonstrations with ski boot prototypes based on the Birdcage it didn’t matter how hard I tried to explain to testers how the dorsal loading system worked and how little force was needed to secure their foot, it didn’t stop them from attempting to crush their foot by tightening down the dorsal plate until their noses bled. They were so conditioned by the persistent, ‘the tighter the boot, the better the ski control’ message that they just didn’t want to believe how little force it takes to activate the auto stiffening mechanism of the longitudinal arch (FIT VS. FUNCTION) and retain the foot in solid contact with the base of the boot.

In order to try and convince testers how little force was required to make their foot dynamically rigid one of our team members had a device we called the Logan Chassis designed and fabricated. The photo below is of the Logan Chassis aka The Convincer.

If it’s not obvious from the photo  the Logan Chassis was very heavy. The components were milled from solid blocks of aluminum. The heel counter and a few other components are missing. But the photo should give you a good enough idea. This thing was a tank. This device was not intended for skiing. It was a pre-ski boot skiing test conditioner.

To demonstrate how little force it takes to make the foot so rigid it is like steel I would get the test subject to put their foot in the Logan Chassis. Then I would try to get them to adjust the knob on the screw to the point where it applied firm but gentle pressure on the dorsum of their foot making sure there was no discomfort. Then I would ask them to stand up and lift the foot in Logan Chassis off the floor and tell me what they felt. They were shocked. Hell, I was shocked when I tried this.

The Logan Chassis feels incredibly light and the foot feels glued to the base with no sensation of pressure or discomfort. It defies logic. But I doubt I would have to convince da Vinci.

The truth is whatever people are willing to believe.

The problem is that most skiers have been convinced to believe that tight is not just right, tight is might.

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.