Ski boot modification posts

THE 2018 SOELDEN GS: A LITMUS TEST OF DYNAMIC STABILITY

Challenging  course conditions, especially in GS, are the litmus test of dynamic stability. The 2018 World Cup GS at Soelden had challenging conditions in spades.

The ability to rapidly achieve dynamic stability across the inside edge of the outside ski is key to moving the Center of Force forward to the point where the biokinetic chain of the outside leg attains sufficient tension to enable the stretch reflex. The stretch reflex (SR) can then modulate pertubations due to asperities in snow surface and terrain with ankle strategies. The principle muscle in ankle balance synergies is the soleus. Dynamic stability enables a racer to float between turns, accelerate under gravity then land on line and load the outside ski. A racer with good dynamic stability is on and off the edges in milliseconds and back into the float phase. Like a skilled gymnast elite skiers and racers can choose their line and stick their landing. Tessa Worely excelled at this in the 2018 Soelden GS.

Tell Tale Signs of Dynamic Stability

Key indicators of dynamic stability are a quiet upper body and the speed at which a racer achieves their line and crosses over into the new turn with their upper body. It’s like watching a flat rock thrown low skipping off water; fly-skip-fly-skip.

In my post, WHY YOUNG TALENTED SKI RACERS FAIL AND EVENTUALLY QUIT RACING (1.), I discuss the 3 levels of balance:

  1. The first reaction is the myotatic stretch reflex, which appears in response to changes in the position of the ankle joints, and is recorded in the triceps surae muscles. This is the earliest mechanism, which increases the activity of the muscles surrounding a joint that is subject to destabilization. Spinal  reflex triggered by the myotatic stretch reflex response causes the muscle to contract resulting in the stiffening of the surrounding joints as a response to the stimulus that has disturbed the balance. For example, changes in the angle of the joints of the lower limbs are followed by a reflexive (fascial) tensioning of adjacent muscles. The subsequent release of the reaction prevents excessive mobility of the joints and stabilises the posture once again.
  2. The next reflex in the process of balancing is the balance-correcting response, which is evoked in response to a strongly destabilising stimulus. This reactive response has a multi-muscle range, and occurs almost simultaneously in the muscles of the lower limbs, torso and neck, while the mechanisms that initiate the reaction are centrally coordinated.
  3. The last of the three types of muscular reaction is the balance-stabilising response. In a situation of a sudden loss of balance, a myotatic stretch reflex first occurs and is then is followed by a balance correcting response, which prevents or attempts to prevent a fall.

I call these balance responses Green (postural reaction 1), Orange (postural reaction 2) and Red (postural reaction 3).

If a racer is no able to use the myotatic reflex (Green = Normal) balance response, the CNS shifts to Level 2 (Orange = Caution) or even Level 3 (Red = DANGER).

Level 1 balance is characterized by a stable, well-controlled upper body (aka quiet upper body) with well controlled and directed positions of the arms.

When the myotatic (stretch) reflex is compromised by restriction of the ankle flexion range required to tension the soleus the balance system will shift to level 2 or level 3 depending on the degree of interference. As the degree of interference with required range of ankle flexion increases the degree of reflexive balance will progress from small, rapid, reactive arm movements to gross reactive arm movements that eventually include gross movements of the torso.

The authors of the Polish skier balance study cited in my post state that ski boots exclude the ankle joint complex from the process of maintaining the stability of the body. However, I don’t believe this is the case with all skiers and especially all racers as evidenced by Soelden video of Tessa Worley, Federica Brignone and Michaela Shiffrin. In my next post I will discuss what I look for in analyzing that suggests dynamic stability and especially a lack of dynamic stability and the indications of compromise and the potential cause.

In the meantime, here’s something to think about.

Early in my boot modification career I came to the conclusion that some skiers, especially racers, were born with the right shape of feet and legs (2.) and this explained why they could ski in ski boots right out of the box with minimal or no modifications better than the majority of skiers even after extensive boot modifications. In a recent series of posts I discussed the results of the 2012 skate study that I modified hockey skates for; the NS (New Skates – Blue bars in the graphics below). The modifications I made were based on ski boot modifications that had resulted in dramatic improvement in performance and race results. Although I optimistically predicted improvements in performance metrics of at least 10% (110%) based on my experience with World Cup skiers, I knew that there was the possibility of a wild card competitive skater who was already close to their maximum performance in their OS (Own Skates – Red bars in the graphics below). If this were the case the skater would realize minimal improvement from the New Skates.

My previous posts only included the results for four competitive skaters. There were actually five competitive skaters in the study. Skater number 1 was the wild card. Look what happened to the results when the wild card skater was added.Look carefully at the graph of the Impulse Force below. Compare Skater number one’s Impulse Force results with the Peak Force results in the preceding graph.This raises the question: Do Tessa Worely, Federica Brignone, Mikaela Shiffrin and other top World Cup racers have the right shape of feet and legs or do they have the right modifications made to their ski boots.


  1. (https://skimoves.me/2017/02/15/why-young-talented-ski-racers-fail-and-eventually-quit-racing/)
  2. THE IDEAL SKIER’S FOOT AND LEG – https://wp.me/p3vZhu-qf

 

 

 

IS ‘SUBTALAR NEUTRAL’ SKIINGS’ HOUSE OF CARDS?

If you purchased custom footbeds for your ski boots or had your ski boots custom fit you may have been told that your foot was placed in subtalar neutral and that this created the strongest position of the bones of the foot and leg for skiing. Neutral in this context refers to a neutral configuration of the subtalar joint of the ankle/foot complex.

As best I can recall, the term subtalar neutral began to emerge in the ski industry about 1978. The authoritarian manner in which it was presented and promoted suggested that it was science-based and supported with evidence that conclusively demonstrated superior performance. But I never saw or heard any explanation as to how subtalar neutral could create the strongest position for skiing of the bones of the foot and leg and I have still not seen such an explanation.

Back in 1978, I didn’t even know what the subtalar joint was. I couldn’t envision how the bones of the foot and leg could be maintained in a specific configuration while foam was injected into a liner around the foot and leg or through some other custom fit system. But in spite of the lack of even a theory to support the premise of subtalar neutral as creating ideal biomechanical alignment of the bones of the foot and leg for skiing the premise seemed to be readily accepted as fact and quickly became mainstream. By the time The Shoe in Sport (which questioned the principles on which the plastic ski boot is based) was published in 1989 (1987 in German), neutral subtalar was firmly entrenched in the narrative of skiing.

In my US Patent 4,534,122 (filed on December 1, 2013) for a dorsal support system that I called the Dorthotic, I had unkowingly tried to fix the subtalar joint in a static position as evidenced by the excerpt below from the patent:

The system of the invention applies significant pressure to the dorsal (upper) surface of the foot over the instep, including the medial and lateral aspects thereof, and hence to the bones of the mid-foot to substantially prevent these bones from moving relative to each other.

Note: The prior art refers to the current paradigm in existence.

The objective of the dorsal support system was to immobilize the joints of the bones below the ankle in conjunction with the joints of the bones of the midfoot while allowing unrestricted dorsi-plantarflexion of the ankle joint within it’s normal range of motion. But the significant medial (inner) pressure applied by the  system to the bones of Podborski’s foot below his ankle made it difficult for him to stand and balance on one foot with the system in a ski boot shell even on the concrete floor of my workshop. Removing the offending structure from the dorsal support system quickly resolved the issue by allowing his foot to pronate. This made me aware that structures that impede supination did not appear to create issues. This insight raised the possibility of a fit system based on selective constraint applied to specific aspects of the foot and leg as opposed to what I termed indiscriminate (general) constraint.

Even though at the time that I wrote my US Patent No, 5,265,350 in February of 1992 I still did not comprehend the mechanism behind the claimed superior performance associated subtalar neutral, I knew enough to know that attempting to fix the subtalar joint in any configuration in a ski boot would interfere with, or even prevent, a skier from balancing on one foot.

Here is what I said in the patent:

The prior art refers to the importance of a “neutral sub-talar joint”. The sub-talar joint is a joint with rotational capability which underlies and supports the ankle joint.

………………….the prior art which teaches, in an indirect manner, that the ideal function for skiing will result from fixing the architecture of the foot in a position closely resembling that of bipedal function, thus preventing monopedal function (balance on one foot on the outside ski).

I later discovered that the above statement came close to the truth.

I also discussed the issue of subtalar neutral in my post NO NEUTRAL GROUND (2.) published on September 1, 2014. But I did not learn about the origins of subtatar neutral and especially the intense controversy surrounding it in professional circles until recently when I came across a discussion on Root and his subtalar neutral theory in an online podiatry forum.

The Origin of Subtalar Neutral

Merton’s Root’s subtalar joint neutral theory was first described in the textbooks, Biomechanical Examination of the Foot, Volume 1. – 1971 (Root, Orien, Weed and Hughes) and Normal and Abnormal Function of the Foot – 1977 (Root, Orien, Weed). The basic premise of Root’s subtalar neutral theory is that a neutral position of the subtalar joint (which Root defined as existing when the foot was neither supinated or pronated), is the ideal position of function in static (two-footed bipedal, erect) stance and in gait where the subtalar neutral theory posited that the foot was pronated in the first half of the stance phase then transitioned through neutral in mid stance to become supinated in the latter half of the stance phase.

Root’s paradigm proposes that the human foot functions ideally around the subtalar joint’s neutral position and that deviations from this ideal position are deformities.

What Root really said

Root and his associates never stated that the joints of the foot should be immobilized in subtalar neutral. The reference to static in subtalar neutral as the ideal position of function in static stance pertained to a subject standing in place in an erect bipedal stance on a flat, level, stable surface with the weight apportioned between the two feet. In this static stance the Root subtalar neutral theory posited that the subtalar joint should rest in neutral. Root and his associates never stated, implied or suggested that the joints of the foot should be configured and immobilized in subtalar neutral. Further, Root and his associates made no reference, of which I am aware, to the application of subtalar neutral to activities other than static stance and gait. Critrics have asserted that a subtalar neutral position in static stance is neither normal or ideal. In defining subtalar joint neutral as normal, Root’s theory implied the existence of abnormal pathologies in the feet of the majority of the world’s population.

The lack of evidence

Critics of Root and his associates “Eight Biophysical Criteria for Normalcy” claim the criteria was nothing more than hunches, that these conjectures were accepted as fact, when, in reality, there was no experimental data or research to support them and that the eight criteria were neither normal or ideal.

 The STJ neutral position problem

One of the early critics of Root and his associates was Kevin Kirby, DPM. He is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt College in Oakland, Ca.

Kirby observed a large error range in determining STJ neutral position on the same foot from one examiner to another. In unpublished studies done during his Biomechanics Fellowship at the California College of Podiatric Medicine, Kirby found that the Biomechanics Professors were +/- 2 degrees (a 4 degree spread) and the podiatry students were +/- 5 degrees (a 10 degree spread)  in determining STJ neutral position.

Subtalar neutral appears to be what amounts to a knife edge between pronation and supination where neutral is the border or transition point between the two states. Unless the subtalar neutral position can be precisely and consistently identified, it is impossible to know whether the subtalar joint is pronated or supinated.

The future of subtalar neutral in skiing

Too many times theories of how the human foot functions and therefore how mechanically inducted foot problems are treated have been presented as if they were facts. The dogmatic adherence that sometimes ensues from such an approach has frequently stifled the evolution of foot mechanics. This has been particularly apparent in the field of podiatry which has been dominated by the Root paradigm. (4.)

The long standing controversy and growing challenges mounted against the credibily of Root’s subtalar neutral theory has significant implications for the continued promotion of subtalar neutral in skiing as providing the strongest position of the bones of the foot and leg.

It may eventually be shown to be unfortunate that Root’s influential textbooks were published at a time when the ski industry was attempting to come to terms with the skier/boot interface issues associated with the new paradigm created by the rigid shell plastic ski boot.

In my next post, I will discuss what a ski boot should do for the user or perhaps, more a case of what a ski boot shouldn’t do.


  1. Root ML, Orien WP, Weed JH, RJ Hughes: Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971
  2. https://wp.me/p3vZhu-Bv
  3. Are Root Biomechanics Dying: Podiatry Today, March 27, 2009
  4. Foot biomechanics- emerging paradigms: Stephen F Albert, 4th Congress of the International Foot and Ankle Biomechanics (i-FAB) Community Busan, Korea. 8-11 April 2014

 

IN THE BEGINNING: HOW I GOT STARTED IN SKI BOOT MODIFICATIONS

I originally published this post on May 12, 2013. This is a revised and edited version.


Before I started ‘tinkering’ with ski boots in 1973, I didn’t just read everything I could find on the subject of fitting boots, I devoured every bit of information I could find on the subject. The assumption I made at that time was that the experts in the field not only knew what they were talking about, but that they also had the requisite knowledge and understanding of the underlying principles to back up their positions with applied science and/or research. Based on this assumption, I started modifying ski boots by doing all the things the experts recommended such as padding the ankle to ‘support’ and ‘stabilize’ it in the boot shell and cuff and adding cants between the soles of the boots and the skis to make the skis sit flat on the snow. But the big breakthrough for me came when I started making footbeds to support the foot.

Within a year I had gained expertise in my craft to the point that skiers from all over Canada were starting to seek out my services. In  response, I started a company called Anatomic Concepts. Soon, I was spending most of my free time working on ski boots. But while I was helping a lot of skiers ski better, none of what I was learning or doing was helping my own skiing. I was still struggling after switching from low-cut leather boots to the new stiff, all plastic boots.

The (Un)Holy Grail

Despite the inability to solve my own problems, my thinking remained aligned with conventional thinking right up until my experience with Mur and the ‘Holy Grail’ of ski boots; the perfect fit of the boot with the foot and leg of the skier.

In 1977, Roger McCarthy (head of the Whistler Ski Patrol), whose boots I had worked, on introduced me to Nancy Greene Raine in the Roundhouse on top of Whistler Mountain. The timing was perfect. Racers on our National Ski Team were having boot problems. They needed help. It was a classic case of me being in the right place at the right time. Nancy recruited me, flew me to Calgary at her expense and introduced me to the National Team and Dave Murray. She set up a working arrangement with the team, one in which I was completely independent. Nancy also introduced me to Glen Wurtele, head coach of the BC Ski Team. At Wurtele’s request, I began working on the boots of members of the team.

I started working on the boots of NAST (National Alpine Ski Team) racers with Dave Murray; ‘Mur’ as he was affectionately known. My thinking at that time vis-a-vis the need to immobilize the foot and achieve a ‘perfect fit’ of the boot with the foot was aligned with the approach of the  ‘experts’ in the  field. Mur didn’t live far from me. When I was working on his boots, he seemed to spend more time at our home than his. Because of my ready access to Mur, I saw an opportunity to achieve the Holy Grail of skiing with a fit of the boot with the foot so perfect that the foot was for all intents and purposes rendered rigid and immobile and united with the structures of the ski boot.

To achieve this lofty goal I spent the better part of 2 weeks working for hours every night carefully crafting a matrix of heat formable 1 mm thick vinyl around Mur’s foot and leg and the shells of his boots with my inserts inside the liners of the boot. When Mur finally confirmed he was ‘loaded, locked and ready’ he went skiing to test the results. I waited for the inevitable confirmation of success and certain celebration that would follow. But after what seemed like an eternity, instead of the expected good news, Mur called to tell me that he could barely ski with my perfect fit. He had little or no balance or control. The Holy Grail had reduced a world class skier to a struggling beginner. I didn’t need to be a rocket scientist to know that the industry had to be way off track especially in view of the recent publication of Professor Verne T. Inman’s seminal book, The Joints of the Ankle.

After this experience I knew that there was way more going on than I understood. I started learning about human physiology, in particular, about the mechanics, neuralbiomechanics and physics of skiing. I started asking hard questions that no one in the industry seemed to have answers for. And I started going off in a very different direction from the one the industry was acquiring increasing momentum in. If the perfect fit could impose what amounts to a severe disability on one of the world’s best skiers I could only imagine what such indiscriminate constraint was doing to the average recreational skier. It could not be good. For me it certainly wasn’t.

A major turning point came for me in 1988 when a husband and wife radiology team who had heard about my efforts to try and develop a ski boot based on anatomical principles presented me with a copy of a medical text called The Shoe in Sport published in German in 1987. This seminal work contains an entire chapter dedicated to The Ski Boot. I discuss the issues raised about the design and fabrication of ski boots by international experts in the articles in chapter on The Ski Boot in my most viewed post to date; THE SHOCKING TRUTH ABOUT POWER STRAPS (1.)

The Root of Misinformation

Unfortunately for skiing, the relevance and significance of the knowledge contained in The Shoe in Sport was overshadowed by the publication in 1971 of the book, the Biomechanical Examination of the Foot, Volume 1 by Drs. Merton Root, William Orien, John Weed and Robert Hughes. The book lists what the authors call their “Eight Biophysical Criteria for Normalcy”. These criteria, which have since been challenged and shown to be largely invalid,  were claimed to represent the “ideal physical relationship of the boney segments of the foot and leg for the production of maximum efficiency during static stance or locomotion”.

A key component of the biophysical criteria was that a bisection  of the lower third of the leg be perpendicular to the ground and the subtalar joint rest in neutral. Root described neutral as occuring when the subtalar joint was neither supinated or pronated.

In order to be considered normal, a foot had to meet all eight biophysical criteria. The effect of this criteria, which was arbitrary, was to render the majority of the feet of the world’s population abnormal and candidates for corrective interventions. Although Root never stated, implied or suggested it, his neutral sub-talar theory appears to have been misinterpretated in the ski industry to mean that the foot functions best in static ski stance when its joints are immobilized in neutral (sub talar).

In recent years, Root’s Sub-Talar Neutral Theory has come under increasing challenge with calls to discontinue its use (2.).

Conclusions
Taken as part of a wider body of evidence, the results of this study have profound implications for clinical foot health practice. We believe that the assessment protocol advocated by the Root model is no longer a suitable basis for professional practice. We recommend that clinicians stop using sub-talar neutral position during clinical assessments and stop assessing the non-weight bearing range of ankle dorsiflexion, first ray position and forefoot alignments and movement as a means of defining the associated foot deformities. The results question the relevance of the Root assessments in the prescription of foot orthoses.

The results of the wider body of evidence have the potential to have profound implications for skiing in terms of the application of Root’s Subtalar Neutral Theory as putting the foot in the most functional position for skiing by supporting and immobilizing it in neutral (subtalar).


  1. https://wp.me/p3vZhu-UB
  2. https://jfootankleres.biomedcentral.com/articles/10.1186/s13047-017-0189-2

SKI BOOT ASSESSMENT PROTOCOL

Step 1 of the synergy 5 Step performance Program described in my last post is a Footbed Check using the Novel Pedar insole pressure analysis system.

Step 3 of the program is the Ski Boot Assessment detailed below. As with the 5 Step performance Program, the Ski Boot Assessment protocol and report were intended to serve as a template to base future programs on. The assessment report was intended to provide clients with information on the effects of their ski boots on their performance and/or as a work order for them to take to a boot-fitter to have any necessary issues identified in the report addressed.  Synergy Sports Performance Consultants Ltd. did not sell products or perform boot modifications.

 



My next post will be called FOOTBEDS: THE GOOD, BAD AND THE UGLY.

 

 

 

 

THE SKI BOOT FLEX INDEX INSTABILITY PROBLEM

It has been known for decades that an unbalanced moment of force or torque will be present on the outside ski when the center of pressure of the load applied to the ski by a skier is acting along the center of the transverse axis of the ski where it is offset from GRF acting along the inside edge. Ron LeMaster acknowledges the existence of an unbalanced moment of force on the ouside ski in both The Skier’s Edge and Ultimate Skiing (Edging the skis). LeMaster states in Ultimate Skiing;

The force on the snow is offset from the center of the skier’s and creates a torque on it that tries to flatten the ski.

Ron didn’t get the mechanics right. But he correctly shows the unbalanced torque acting on the ankle joint. LeMaster tries to rationalize that ice skates are easy to cut clean arcs into ice with because the blade is located under the center of the ankle. While this is correct, ice skaters and especially hockey players employ the Two Stage Heel-Forefoot Rocker to impulse load the skate for acceleration. Hockey players refer to this as kick.

In his comment to my post, OUTSIDE SKI BALANCE BASICS: STEP-BY-STEP, Robert Colborne said:

…..In the absence of this internal rotation movement, the center of pressure remains somewhere in the middle of the forefoot, which is some distance from the medial edge of the ski, where it is needed.

The load or weight of COM is transferred to distal tibia that forms the ankle joint. This is the lower aspect of the central load-bearing axis that transfers the load W from COM to the foot. What happens after that depends on the biomechanics. But the force will tend to be applied on the proximate center of the stance foot. This is a significant problem in skiing, (one that LeMaster doesn’t offer a solution for) when the ski is on edge and there is air under the body of the ski. The unbalanced torques will move up the vertical column where they will manifest at the knee against a well stabilized femur.

But this unbalanced torque creates another problem, one that is described in a paper published in 2005 by two Italian engineers (1.) that describes how this load deforms the base of the boot shell.

The Italian study found large amounts of deformation at mean loads of up to 164% body weight were measured on the outer ski during turning. The paper suggests that the ski boot flex index is really a distortion index for the boot shell. The lower the flex index, the greater the distortion potential.

For the ski-boot – sole joint the main problem is not material failure, but large amounts of local deformation that can affect the efficiency of the locking system and the stiffness of the overall system.

Values of drift angle of some degree (>2-3°) cannot be accepted, even for a small period of time, because it results in a direct decrease of the incidence of the ski with the ground.

My post GS AND KNEE INJURIES – CONNECTING THE DOTS (2.) cites studies that found that knee injuries are highest in GS in the shortest radius turns where peak transient forces are highest.

As shown in Figure 2a FR (sum of centrifugal and weight forces) and F GROUND (ground reaction force) are not acting on the same axis thus generating a moment MGR that causes a deformation of the ski-boot-sole system (Figure 2b) leading to a rotation of the ground reaction force direction. The final effect is to reduce the centripetal reaction force of the ground, causing the skier to drift to the outside of the turn (R decreases, causing the drift event).

An imperfect condition of the ski slope will emphasize this problem, leading to difficulties maintaining constant turning radius and optimal trajectory. The use of SGS ski-boot in competitions requires a particular focus on this aspect due to the larger loads that can be produced during races.

I have added a sketch showing that the moment arm M R created by the offset between the F Ground and F R is in the plane of the base of the ski where it results in an Inversion-lateral rotation torque.

The importance of sole stiffness is demonstrated with a simplified skier model…..…ski boot torsional stiffness with respect to ski longitudinal axis in particular is very important as it deeply influences the performance of the skier during turning…. A passage over a bump or a hollow may generate a sudden change in ground reaction force that may lead to a rapid change in the drift angle delta. The ski boot must be as stiff as possible going from the lower part of the boot to the ski (i.e. lower shell-joint-sole system)

As explained in the method section using the simplified model, values of some degree cannot be accepted, even for a small period of time, because the skier stability and equilibrium could be seriously compromised especially when the radius of curvature is small. A non perfect condition of the ski slope will emphasize the problem, leading to big difficulties for maintaining constant turning radius and optimal trajectory.

This excellent paper by the two Italian engineers concludes with the following statements:

Authors pushed forward the integration of experiments and modeling on ski-boots that will lead to a design environment in which the optimal compromise between stiffness and comfort can be reached.

The possibility of measuring accurately the skier kinematics on the ski slope, not addressed in the presented study, could represent a further step in the understanding of skiing dynamics and thus could provide even more insightful ideas for the ski-boot design process.

I first recognized the shell deformation, boot board instability issue in 1980, at which time I started integrating rigid structural boot boots into the bases of boot shells I prepared for racers. The improvement in ski control and balance was significant. The instability of  boot boards associated with shell/sole deformation with 2 to 3 degrees of drift at modest loads of up to 164% body weight has significant implications for footbeds.


  1. AN INNOVATIVE SKI-BOOT: DESIGN, NUMERICAL SIMULATIONS AND TESTING – Stefano Corazza 􀀍 and Claudio Cobelli Department of Information Engineering – University of Padova, Italy – Published (online): 01 September 2005 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3887325/
  2. http://wp.me/p3vZhu-zx

SHOE/LINER HACKS

There is no point in continuing my discussion of the mechanics of balance on the outside ski because the odds are great that ski boots are preventing most skiers from engaging the mechanics required to apply the torsional forces to a ski with which to establish a balance platform under the outside foot.

In the scheme of things, an essential first step is to adapt the ski boots to functional needs of the skier as opposed to forcing the skier to adapt to the limitations imposed on them by the ski boots. Tightly fitting, supportive ski boots and most conventional constricting, cushioned, supportive footwear actually makes the feet weaker while compromising postural alignment and balance. There is an emerging global movement that is recognizing conventional footwear as THE problem behind compromised foot function while creating a ‘perceived need’ for cushioned soles  and artificial support in the form of custom insoles and orthotics which, instead of solving functional issues in the feet, lower limbs and entire body, further weaken the biokinetic chain.

The links below are to 3 articles that speak to this subject.

ORTHOTICS OR NOT => OUR LIMITING FOOT BELIEFS ARE HURTING US – http://kristinmarvinfitness.com/orthotics-or-not-our-limiting-foot-beliefs-are-hurting-us/

YOU WERE BORN WITH PERFECT FEET – https://www.correcttoes.com/foot-help/feet-101/

STRENGTHENING VS. SUPPORTING: THE COMPETING LOGIC OF FOOT HEALTH – https://www.correcttoes.com/foot-help/strengthening-vs-supporting-competing-logic-foot-health/

There is currently a whole series of Foot-Cast Episodes on The Foot Collective site at – http://www.thefootcollective.com

see – THE HUMAN GUIDEBOOK FOR SWITCHING TO BAREFOOT FOOTWEAR


A good starting point is to acquire a sense of how day-to-day footwear compromises foot and lower limb function and the modifications or ‘hacks’  necessary to adapt the footwear to the functional needs of the user.

A recent post on the Correct Toes blog called ‘How to Modify Your Shoes to Better Fit Your Feet’ (1.), comments on a runner who was experiencing distracting numbness and tingling in her feet, but balked at allowing her coach to make a few cuts in the upper material of her shoes to relieve the tension that was causing her problem. Most people are uneasy with the idea of modifying footwear. They tend to readily accept standard, off the shelf shoe size fit and assume that the way a shoe fits (or doesn’t) fit their foot is the way it is supposed to fit.

I recently had a similar experience with a young ski racer whose toes were crunched up in her ski boots that were both too short and too narrow. The liners were especially bad. Like many of today’s young racers, early in her racing career, she had probably grown accustomed to the constraint imposed on her feet by her ski boots and had unconsciously learned to make her feet comfortable by standing with most of her weight on her heels. After a time, her body had come to accept this as ‘normal’. Once this happened, she became reluctant to make changes.

A ex-racer, who I worked with back in the 1970s, loaned the young racer a pair of her boots. The improvement in the racer’s skiing was immediate and remarkable. Her coach commented that she had made 6 months improvement in one day! Unfortunately, stories of skiers and racers whose foot function, balance and even the function of their entire body has been compromised by tightly fitting, supportive ski boots is common. But happy outcomes, such as this young racer experienced, are exceedingly rare.

The Correct Toes post offers some good suggestions on footwear modifications that are remarkably similar to those I have used for decades in both ski boot liners and in my own footwear. The reason the modifications are similar is that the end objective; creating a functional environment for the user by minimizing the negative impact of the footwear on foot function, is the same.

The series of photos that follow illustrate examples of modifications that can improve the functional fit of footwear. An easy modification is to reconfigure the lacing pattern. Just because a shoe has a specific set of lace eyelets does not mean they all are necessary. The 2 photos below are from the Correct Toes article.

Photo with permission of Correct Toes

The photos below are the lace hacks I made on my Xero Prio (left) and Lems Primal 2 (R).

One modification that the Correct Toes article does not mention is the use of lace locks. Lace locks allow lace tension to be regulated and maintained without the need to over tighten laces to prevent them from coming undone.

This is one form of lace locks on my Xero Prio.

This is another form of lace locks on my Lems Primal 2.

I also use Correct Toes to improve foot function.

Correct Toes, The Foot Collective, EBFA, Feet Freex, EM Sports and many others are advancing on a uniform front in lock-step with the makers of minimal shoes in recognizing the damage caused to feet by conventional footwear while moving towards a uniform standard for the design and construction of footwear that creates a functional environment for the foot, while minimizing the negative impacts associated with structures placed on the human foot. Technologies such as NABOSO hold the promise of advancing on barefoot function in what I like to call ‘Beyond Barefoot’.

It has long been my experience that liners are the most problematic aspect of most ski boots. When I worked exclusively with Langes, I often made extensive modifications to liners that included using a liner a size larger than the shell size and re-sectioning and/or re-sewing the forefoot to allow proper alignment of the big toe and adequate width for the forefoot to fully splay.

The biggest problem in ski boot liners is in the toe box, especially the shape of the toe end in that it forces the big toe inwards, towards the center of the foot.

A modification that the Correct Toes article suggests is to make small slits on the side of the footwear opposite the point where the foot needs more room to splay.

Photo with permission of Correct Toes

Cutting small slits along the base of a ski boot liner is the first hack I usually try. But in many cases, I find more drastic modifactions are necessary in order to obtain the width required for the foot to fully splay and the big toe to align properly.

The photos below are before (L) and after (R) modifications that were necessary to accommodate my wife’s feet. These are older race stock Lange liners which I fit to her extensively modified Head boot shells.

The photo below is of the modified liner from my Head World Cup boot.

For ‘shallow’ feet or feet with a low instep the Correct Toes article suggests adding tongue depressors along the top of the foot or under the laces to help fill the void and prevent the foot from lifting or sliding around.Photo with permission of Correct Toes

The photo is of forefoot/instep retention pad that applies a constraining load to the foot that is substantially perpendicular to the transverse plane of the boot board. This device is similar to the one that powered Steve Podborksi to the podium in World Cup Downhill races. Today, Steve remains the only non-European to have ever won the World Cup Downhill title.

I devoted a large portion of my US Patent 5,265,350 to laying the groundwork for a functional standard that could evolve and eventually be applied to all forms of footwear, but especially ski boots. There are encouraging signs that the ski industry has finally started to take baby steps in this direction. I will discuss this in my next post.


  1. https://www.correcttoes.com/foot-help/modify-shoes-better-fit-feet/ 

SYNERGY: A MULTI-DISCIPLINARY APPROACH TO SKIING

Introduction

In 1991, when I designed the research vehicle called the Birdcage and sometimes simply The Gadget, with Alex Sochaniwskyj, P. Eng., a biomedical engineer, we employed a multi-disciplinary approach; one that encompassed as many factors as possible. In his letter of support for my nomination for the Gold Medal in Applied Science and Engineering in 1995 British Columbia Science & Engineering Awards, Alex said:

During 1991 and 1992, I had the opportunity of working with David MacPhail in the realization and testing of conceptually innovative sports footwear. Design of this type requires, knowledge, understanding and experience in a combination of disciplines including anatomy, physiology, biomechanics, sports dynamics, physical mechanics and design. David MacPhail exhibited this unique combination throughout all aspects of the project, and continues to research and explore developments in: influences of footwear on the kinematics and kinetics of human movement; the design of athletic footwear; and the etiology, occurence, frequency and prevention of athletic injuries.

Alex Sochaniwskyj, P. Eng.

Synergy

In 2000, I formed a partnership with Joanne Younker, a CSIA Level IV ski pro and coach at WhistlerBlackcomb and Sophie Cox, a podiatrist from London who was trained by Novel Germany in the use of their Pedar insole pressure analysis system. Our collective efforts and expertise formed a complimentary multi-disciplinary core that we augmented with other expertise such as physiotherapy, chiropractic and myofascial release therapy.

 

 


Originally published in Whistler’s Pique Newsmagazine on February 18, 2000 under the title DIGITAL SALVATION FOR THE SOLE [BACK TO THE FUTURE]

“Any sufficiently advanced technology is indistinguishable from magic.”  – Clarke’s Third Law

Conspicuous hardly begins to describe what I was feeling.  In the early morning rush of skiers grabbing a quick caffeine rush at the Wizard Grill, amid tables full of Ski School twinks waiting to see whether they were going to have any work for the day, an attractive woman was carefully stringing computer cables up the inside legs of my ski pants.  Things like that draw attention even at the base of Blackcomb on a Monday morning.

One end of the cables were attached to pressure sensing insoles in my ski boots, the other to a data recording box I was trying to figure out exactly were to attach.  About the size of an epic Michener paperback, it was just too big to slip into any of my pockets.  Finally clipped to the waist of my pants, it was, in turn, coupled to a high-powered flash unit strapped to my arm, both of which were fired by a button left dangling pretty much nowhere.

Robocop.  I couldn’t get the image out of my head, although at least one person who asked what all the hardware was about accepted my answer that it was a control mechanism to power my artificial leg.

David MacPhail grabbed the digital video camera and we headed up Blackcomb to take some measurements.  Dave — who I’d been working with to document some background on the Rise boot he’s been developing — had only recently launched Synergy Sports Consultants.

I wasn’t clear where exactly he was taking me or what we were going to accomplish, but a more willing guinea pig would have been hard to find.  In the nether world of ski theory, and more particularly in the areas of skiing biomechanics and modeling, Dave MacPhail is riding the cutting edge.  His work with National Team skiers and his understanding of exactly happens to the human body when it straps on a pair of skis has brought him an international reputation as an authority in the field.

On a clear slope under the Solar Coaster, Dave skied ahead to set up the video shot.  Sophie — who’d wired me up — rechecked the cable connections, set a baseline measurement for each of my unloaded feet and told me to point the flash unit down the hill at the camera.

As they signaled their readiness to each other, Sophie fired the flash and told me to ski down toward Dave.

Making my best ski school turns, I skied for the camera.  We repeated the process a few times and then we went back down to the Daylodge to…well, I wasn’t sure to do exactly what.

What, turned out to be mind blowing.  The unit strapped to my waist was a Pedar foot pressure data recorder from the Novel company of Munich, a techy little piece of equipment that, until last year, was the size of a small desk.  On a PCMCIA flash card, the unit was capable of recording about 10 minutes worth of data.  Fed by 80 pressure sensors arrayed throughout the insoles in my boots that each took 50 measurements per second, the Pedar tracked pressure across time as my feet worked to move me like a skier.

Downloaded onto a laptop computer and run through the company’s software, the data could be displayed as images of my left and right foot, colour-coded across the sensing mechanisms to display the changes in foot pressure as I made turns.  With lower pressure readings showing up as black squares and higher pressure lighting up bright pink, the readout was a moving kaleidoscope of colour as it played back my runs down the mountain.


On each colourful foot profile, a small dot traced a red line showing my centre of pressure at any moment in time.  A good skier using foot pressure the way they’re supposed to, would, over the course of a run, track a red line from the ball of their foot back toward their heel.  The track would be true and relatively straight with few variations.  That’s what the tracing on my right foot looked like.  The track of pressure of my left foot looked like someone who had never seen an Etch-A-Sketch grabbed both knobs and started twisting them randomly.

The difficulties showing up in my left foot readout were verified when Sophie explained the graphic display at the top of the screen.  “This line graph shows change in pressure over time for each foot.  When you make a good turn, like you’re doing with your right foot, the graph of pressure shoots up dramatically at the start of the turn, drops down slightly to a plateau, then falls away as you unweight the foot at the beginning of the next turn.  Your left foot comes on very gradually.  Something’s blocking your foot function,” she explained.

The final diagnostic piece of the puzzle — at least as far as the technology end of things went —was put in place when Sophie downloaded the images from the digital video camera and synchronized them with the Pedar display.  There I was, making graceful turns and there was the readout of what my feet were doing — or not doing, as it turned out.

“Neat,” I said.  “Now what?”
“Now you find out what Synergy is all about,” said Dave.

Synergy — small “s” — is about joint action of different substances producing an effect greater than the sum of the effects of all the substances acting separately.

The whole being greater than the sum of the parts. 

In a theological context, synergy is a doctrine that human effort cooperates with divine grace in the salvation of the soul.  I’ve often thought of skiing as a salvation of the frozen Canadian soul and certainly a day in the high alpine making perfect turns in all conditions is as close to divine grace as most of us will ever come.  But it was the more secular meaning of the word Dave had in mind in naming the company.

“The whole concept of Synergy probably came into my mind 25 years ago.  I started thinking about something called bio-integration, bringing people with different important skills together to work holistically on making your body work right.  Five years ago, we couldn’t have launched Synergy because the technology wasn’t quite there.  We needed more sophisticated software and I could see the time coming closer to when we’d reach a point where a lot of things in athletics that are mysteries now were going to be revealed by being able to plug in sensors at key points of interface.  Now, we’re starting to get there.”

But data is just data without something to make it sing.  And that’s where the principals of Synergy begin to make the concept work.  Joanne Younker is Synergy’s president. She’s been working with Dave for 12 years on both the Rise boot and putting together a biomechanical model of how people ski, how joints and muscles and nerves and bones work together to overcome our natural tendency to fall down when the earth starts to slide out from under our feet at an accelerating rate.

Joanne’s a level IV CSIA instructor and a level II CSCF coach and a personal trainer when she’s not on skis.

Sophie Cox and Joanne Younker

She’s been a keen skier since she was fourteen and a student of kinaesthetics since 1989 when she blew her back out squatting improperly in the weight room, an injury leading to temporarily paralysis and a burning desire understand how her body works.

“Working with David, and studying the biomechanics of skiing, I can look at someone skiing and understand what they’re doing wrong and, more importantly, probably why they’re doing it.  That is, what muscles aren’t functioning right or what functions are blocked.  Working with this technology, I can validate my diagnosis with hard data.”

Using a set of dry-land kinaesthetic exercises, Joanne led me through a session designed to help me experience the “feel” of having the right muscles firing and applying pressure with the correct area of my feet.  Once I’d managed to do these correctly, she had me stand on the Pedar’s insoles outside my ski boots.  Connected to the computer, they gave me a real time display of where, in turn, I was applying pressure with each foot. Running me through the exercises again, I could use the display to associate that “feel” with a visual representation of correct pressuring.  There was no guesswork.  When I lit up the right area of the pressure pads, I was having my feet do exactly what they should do to initiate a good turn.

The final step of the exercises was to slip the insoles back into my ski boots and repeat the exercises again.  Within the confines of my boots, I could watch as I pressured the ball of my foot and got my bulk into the right plane of alignment.  I was surprised — as is virtually everyone else who has gone through this exercise — at how far forward I really needed to bring my centre of mass to consistently apply pressure where needed.

All of this might have taken a lot longer to happen if the third member of the Synergy team hadn’t walked into town by accident.  Sophie Cox finished her B.Sc. at the University of Brighton School of Podiatry in, England, in the summer of 1998 and was working in a Podiatry clinic in London.  Her mother brought home a bottle of Whistler spring water  — the same water that gets flushed down toilets in Function Junction, ironically — and she was taken with the idea of goofing off for a year in Whistler.  After some web surfing, she decided to take a job as a bootfitter at Can-Ski and really learn how to ski and party, Whistler style.

A colleague in Boston mentioned the groundbreaking work Dave had been doing in biomechanics and planes of movement associated with skiing to her and she attended a presentation Dave made last March to the Congress of the Canadian Sports Medicine Association.  “After Sophie met David and explained what she’d been doing with the Pedar, he was really excited.  He called me up and said, ‘I’ve met the third person!’ and we went from there,” Joanne explained.

After a summer back in England working , Sophie returned this fall to work with David and Joanne on the biomechanics of skiing and help launch Synergy.  What she brings to the table, in addition to the technology, is an in-depth understanding of the structures and movement of the foot and ankle joints and a wealth of knowledge in diagnosing problems related to feet and lower limbs.

“I look at a skier’s mechanics, what they can and can’t do, and try to decipher why they can’t do it.  Sometimes it’s bad motor skills and that’s Joanne’s part.  But if she’s trying to teach them a skill and they just don’t have the biomechanical capability to do it, that’s where I come in.  I can determine the physiological problem and refer them on to a physio or bootfitter or local podiatrist.”

“The only way of discovering the limits of the possible is to venture a little way past them into the impossible.” 

                                                                                                                                                      – Clarke’s Second Law

For me, the proof of what Synergy was offering was back out on the slopes.  I practiced and visualized what Joanne had shown me, let Sophie make a few modifications to my left footbed and got wired up again a few days later.  Back at the computer after two or three runs, I sat in rapt amazement at the difference.

On the Pedar’s readout, the front of my feet were lighting up at the initiation of each turn.  The tracking line of the centre of force had moved inward — indicating a much stronger pronation, getting the ski on its edge — and my left trace looked like something made by a functioning foot instead of a peg leg.

I know what you’re thinking; almost anyone can help me be a better skier.  That’s like crowing about doubling your money when you only have fifty cents to start with.  But what about good skiers?  What can all this do for them?
Funny you should ask.

In the fall of 1991, during dry-land training in Banff, Rob Boyd blew a disc at the L-5, S-1 joint in his back.  An ensuing laminectomy restricted his mobility and left some nerve damage on his right side— although not enough to keep him off the podium from time to time for the next six years.  “I learned to compensate using different muscle patterns,” he said.

Screen Shot 2017-05-14 at 2.11.09 PM

Three years off the World Cup Circuit now, and away from the daily coaching, Rob wasn’t happy with the way he was skiing this season, nor was he happy with his finishes in the early Ford Pro Series downhill races.  “I saw Jim DeMarco, M.D. wired up to this thing one day and started thinking maybe Dave — who had done a lot of boot work for Rob in the past — could do some testing on me and help me find some answers.”

Sophie and Joanne ran Rob through a gait test, using the pressure pads inside his running shoes while he walked the treadmill at Meadow Park.  “What we saw,” Sophie related, “was Rob had some blockage in the way his foot was functioning.  He wasn’t pushing off the ball of his foot with any force at all but compensating through other muscle patterns.”

Screen Shot 2017-05-14 at 2.10.31 PM

“Right away, from what we saw on the data, my suspicions were confirmed that my right side wasn’t working well,” Rob added.

What they saw when Rob was hooked up to the Pedar for the first time on the slopes was even more surprising.  His heels lit up like a Christmas tree and he was almost never pressuring the front of his boot.  His left turns were strong and crisp but his right turns were nowhere near the same intensity.  “Yeah, that was surprising to see.  It felt like I was skiing alright and using the balls of my feet but I wasn’t even close,” Rob said.

Dave went to work on Rob’s boots, Sophie made some modifications to his footbeds and Joanne got him started on a series of patterning exercises and visualization techniques.  “I could really feel the difference when I started concentrating on using my foot more.  That and the changes in my boot environment made a big difference.  I could feel it right away at Sugarbush (Vermont).  My skis were gliding on the flats; just floating,” Rob said.  He could also see the results in his times: second on his first run and fourth on his second.

Sophie Cox, making adjustments to the Pedar system on Whistler’s Rob Boyd.

Rob Boyd on the Pedar screen.

“The next step will be to set Rob up with a physiotherapy regimen with Allison MacLean,” Joanne said.

And that’s where the remaining synergy of Synergy comes into play.  The company’s goal is to actively work with bootfitters, physiotherapists, chiropractors and other specialists in the community who can treat the whole person.

Allison is just beginning to work with the Synergy people and is excited about the “integrated approach” they’re trying to bring to problem solving.  “The data gathering and testing they’re doing is interesting,” she told me.  “It’s hard sometimes to know exactly what’s not functioning in the case of lower limb injuries and whether what your treatment is as effective as it could be.  When they send someone to me, we’ve got a pre-treatment set of data we can compare to post-treatment performance to really know whether what we’re doing is effective.”

“Every other person you bring into this adds something to the mix and produces even more beneficial results,” Dave explained.  “Sophie and Joanne and I, working together, have a much greater impact than any one of us could have on our own.  That’s the genesis behind Synergy.  But we want to bring the best resources we can to bear and make it so everybody looks like a hero.”

This obviously includes some of the best bootfitters in town.  George McConkey is sold on the idea.  “What Synergy is doing validates a lot of my own ideas about foot function and bootfitting,” he said.  “I still believe 99% of most peoples’ problems are in their boot and with any luck, what we’re starting to see in the way of data coming out of this will get the manufacturers interested in designing boots that work.”

Scott Humby, one of the owners of Fanatyk Co., isn’t so sure what’s going on is going to shake up the industry, but he sees potential benefit.  “I think what they’re doing can help you by really proving what’s going on in your boots.  If it make you feel better about your skiing; you’ll ski better.  If, as bootfitters, we’ve done all we can for someone and they’re still struggling, we’ll definitely send them on to Synergy because there may be something we’re just not seeing.  There’s a huge benefit in being able to refer someone on to a team of specialists.”

It seems axiomatic that what Synergy is doing is the way sports will go in the future.

The advances in sports in the last 25 years have largely come about because of a refinement in coaching techniques and technological innovations in equipment.  But most of what’s being done on the coaching front still relies on what a coach can see and how he or she interprets that visual data.  The advances in coaching and teaching in the next 25 years will probably be realized through the application of measurement technologies only now being brought into the field.

Some people in town and on the mountains think what Dave’s up to is another bit of high-tech quackery, other’s are true believers.  But whether coaches and instructors and others who guide athletes embrace the kinds of tools is probably more a matter of when, not if.  Elite athletes will demand it; the wired generation coming up will assume its presence. And guys like me who just want to get better and shorten the distance between muscle pattern and muscle memory will embrace it the same way we embraced those shapely new skis we can’t live without.

In the meantime, Arthur C. Clarke’s Law of Revolutionary Ideas is probably apropos:

Every revolutionary idea — in science, politics, art or whatever — evokes three stages of reaction. They may be summed up by the three phrases:

1. “It is completely impossible — don’t waste my time.”

2. “It is possible, but it is not worth doing.”

3. “I said it was a good idea all along.”

Watch out for number three.

author- J.D. Maxwell


reprinted with the permission of Whistler Piquenewsmagazine – published on February 18, 2000


Epitaph

For a brief moment in history, skiing stepped out of the shadows of the dark ages into the brilliant sunlight of knowledge. For a brief moment, it was all about the skier. For a brief moment, the skier counted. Then, as if blinded by the light, skiing slipped back into the comfort of orthodoxy and uninformed opinion where eminence trumps evidence.