Footwear science posts

SCHEDULE OF POSTS

The link below will take you to a page with a link to a PDF of all 298 posts I have made since my first post of May 11, 2013.

https://wp.me/P3vZhu-2sM

The schedule lists posts in the order of newest (Jul 10, 2018) to oldest (May 11, 2013). The image below shows what the schedule looks like. The date and time of the post and the views and likes are listed below the title of each post.

 

The top 10 posts to date are shown in the graphic below.

I am in the process of reviewing and analyzing post subjects based on ranking with the objective of better directing my efforts to my readers. If there are any subjects you would like addressed please post them in the comments section.

 

WHAT’S YOUR PQ? [PERFORMANCE QUOTIENT]

After my disastrous experience in 1977 with the mythical Perfect Fit with Crazy Canuck, Dave Murray (.1); one that transformed Mur from a World Cup racer to a struggling beginner, my work on ski boots became focussed on removing instead of adding material and making room to allow a skier’s foot to assume its natural configuration in the shell of the ski boot. As I improved the accommodation of a skiers’ neurobiomechanical functional requirements in the ski boot, skier performance improved in lockstep. I was merely reducing the structures of the boot that interfered with performance to enable a skier/racer to use the performance they already had.

Fit: The Antithesis of Human Function

Fit, by it’s definition of joining or causing to join together two or more elements so as to form a whole, is the antithesis (def: the direct opposite) of enabling the function of the human foot and lower limbs as one of the most dynamic organs in the human body. Fitting a ski boot to the foot and leg of a skier, especially a racer, equates with imposing a disability on them (2.). Although I didn’t realize it until I read The Shoe in Sport and learned of the barefoot studies done at the Human Performance Laboratory at the University of Calgary, my work on ski boots had transitioned from Fitting (disabling), by adding materials to liners to fill voids between the foot and leg and shell wall, to UnFitting (abling) by removing materials from liners and expanding and grinding boot shells so as to accommodate the neurobiomechanical functional requirements of the foot and leg of a skier.

But the big breakthrough for me came when Steve Podborksi won the 1981-81 World Cup Downhill title using the dorsal constraint system (Dorthotic) I developed and later patented. The Lange boot shells the device was used in had the least constraint of any ski boot I had ever worked with. The instantaneous quantum leap in Steve’s performance compared to the same shell using a conventional liner raised the question of how could a skier’s maximum performance be achieved and was there a way to compare to a skier’s performance in different ski boot/liner configurations to an optimal reference standard?

A reliable indicator that my un-fitting was trending in the right direction was that skiers consistently found that skiing became easier. For racers, coaches would typically report that the racer was skiing better. Improved race results served as further confirmation of my efforts. But these indicators were subjective. I wanted a way to not just measure performance with quantifiable metrics generated from data specific to the activity, I wanted to be able to compare the same metrics to a reference or baseline standard that represented the optimal performance of a skier or racer at a given moment in time. Without a way to measure and compare performance there is no way of knowing how a ski boot is affecting a skier or racer and especially no way of knowing how close they are to skiing at their maximum level of performance. I wanted to develop a skier Performance Quotient or PQ.

Definition of Quotient

  • Mathematics: – a result obtained by dividing one quantity by another.
  • a degree or amount of a specified quality or characteristic.

A skier Performance Quotient would capture baseline metrics from a skier’s performance in a ski boot that provides the optimal functional environment for the foot and lower limbs to the skier’s peformance in different ski boots including a skier’s current ski boot. The ski boot that provides the optimal functional environment for the foot and lower limbs would be designated as 100%. If the same metrics captured in a different ski boot were 78% of the reference standard, the skier’s PQ in the ski boot would represent a PQ of 78% against a possible 100% or 78/100.

Raising the bar of skier/racer function with body work and/or conditioning will raise the PQ. But it cannot close the PQ gap created by the performance limitations of the interference with neurobiomechanical function caused by their ski boot. Nor can trying harder or training more intensely overcome the limitations of a ski boot. Assuming 2 ski racers of equal athletic ability and mental strength, the racer with the ski boot that enables a higher PQ will dominate in competition. The only way to improve a skier’s PQ when it is less than 100% is to improve the functional environment of the ski boot.

In current ski boot design process, manufacturing and aesthetic considerations override skier functional requirements. An innovative approach to the design of the ski boot is needed. This is the subject of my next post.


  1. IN THE BEGINNING: HOW I GOT STARTED IN SKI BOOT MODIFICATIONS, May 12, 2013 – https://wp.me/p3vZhu-y
  2. LESS REALLY IS MORE, May 13, 2013 – https://wp.me/p3vZhu-N

 

SKI BOOTS: WHY LESS IS MORE

At the time I filed an application for my second patent in April of 1989 , I had some ideas of what a ski boot should do for the user from what I had learned from the dorsal containment system I was granted a patent for in 1983. But I was still a long way from being able to answer the question.

A watershed moment came for me in 1990 when I read a medical textbook published in 1989 called The Shoe in Sport on what is referred to in the text as ‘the shoe problem’.

The Shoe in Sport, supported by the Orthopedic/Traumatologic Society for Sports Medicine, was originally published in German in 1987 as Der Schuh im Sport. The textbook is a compilation of the collective efforts of 44 international experts, including Professor Peter Cavanagh, Director of the Center for Locomotion Studies at Penn State University, biomechanics experts from the Biomechanical Laboratories at ETH Zurich and the University of Calgary, Professor Dr. M. Pfeiffer of the Institute for Athletic Sciences at the University of Salzburg, Dr. A. Vogel of the Ski Research Syndicate, Dr. W. Hauser and P. Schaff of the Technical Surveillance Association Munich and many other experts in orthopedic and sportsmedicine on  ‘the shoe problem’.

The buyers of athletic shoes are always looking for the “ideal shoe”. They encounter a bewildering variety of options and are largely dependent for information on the more or less aggressive sales pitches that directed at all athletes in all possible ways. (1.)

This volume should assist in defining the role and the contributions of science in the further development of the athletic shoe and in the recognizing of the contributions made by the various research groups, who are all interested in the problems of the athletic shoe. (1.)

Dazzled by the fancy names, the buyers believe that they can match the athletic performance of the champion who wears “that shoe,” or after whom the shoe is named. The choice is not made easier by the plethora of promises and a roster of specific advantages, most of which the merchant cannot even explain. (2.)

When The Shoe in Sport was first published in 1987, the field of biomechanics was in its infancy as was the associated terminology. This created an opportunity for a new marketing narrative of techno buzzwords. Since the consumer had no way to understand, let alone assess, the validity of any claims,  the only limits to claims made for performance was the imagination of the marketers. Consumers were increasingly bombarded with features that far from recognising the human foot as a masterpiece of engineering and a work of art as espoused by Leonardo da Vinci, suggested the human foot is seriously flawed and in need of support even for mundane day-to-day activities. These marketing messages distract attention away from the real problem, the design and construction of shoes and their negative effect on the function of the user; the modern ski boot being one of the worst examples.

The Shoe Problem

For this reason, the “shoe problem”as it exists in the various fields of athletic endeavour, will be studied with respect to the biomechanical, medical , and technical aspects of shoemaking. The findings (criteria) should enable the interested reader to distinguish between hucksterism and humbug on the one side and the scientifically sound improvements in the athletic shoe on the other. (1.)

Form follows Human Function

The Shoe in Sport focusses on the medical orthopedic criteria in offering guidelines for the design of shoes for specific athletic activities including skiing and ice skating.

Less attention will be paid to the technical and material aspects of the running surface and shoe, and more to the medical and orthopedic criteria for the (design of) athletic shoe. For this reason, the “shoe problem”as it exists in the various fields of athletic endeavour, will be studied with respect to the biomechanical, medical , and technical aspects of shoemaking. 

This volume should assist in defining the role and the contributions of science in the further development of the athletic shoe and in the recognizing of the contributions made by the various research groups, who are all interested in the problems of the athletic shoe.

Barefoot as the Reference Standard

Research done at the Human Performance Laboratory at the University of Calgary found that optimal human performance is produced with the unshod foot and that human performance is compromised by the degree of interference; the greater the interference caused by any structure appended to the foot, the greater the compromise of performance. This is true even for a thin sock.

The authors of The Shoe in Sport ask:

Is there really a need for shoes? The examples of athletes like Zola Budd and Abebe Bikila suggest in a technologic environment the evolution of the athletic shoe parallels the decline of our organs of locomotion. (1.)

The Future of the Ski Boot

The shoe affects the athlete’s performance and serves to support the foot as a tool, as a shock absorber, and as a launching pad. Giving serious consideration to our organs of locomotion opens up an enormous area of activity to the athletic shoe industry. (1.)

This is especially true of the ski boot. The questions that needs to be asked is how does the structure of the ski boot affect the human performance of skier and what is the minimal combination of structure that will enable maximum skier performance.

Few forms of athletics place as high demands on the footwear used in their performance as alpine skiing. It (the ski boot) functions as a connecting link between the binding and the body and performs a series of difficult complex tasks. (3.)

Before the question of what structure of a ski boot will maximize skier performance can be answered, the functional mode of the human system in the complex physical environment associated with skiing must be known. The first and most important and fundamantal component of this question is explaining the mechanism by which the human system is able to achieve a state of balance on the outside ski characterized by neuromuscular control of torques in all 3 planes across the joints of the lower limb and pelvis.


  1. Introduction by Dr. med. B. Segesser, Prof. Dr. med. W. Pforringer
  2. 2. Specific Running Injuries and Complaints Related to Excessive Loads – Medical Criteria of the Running Shoe by Dr. med. N. L. Becker – Orthopedic Surgeon
  3. Ski-Specific Injuries and Overload Problems – Orthopedic Design of the Ski Boot –  Dr. med. H.W. Bar, Orthopedics-Sportsmedicine, member of GOTS, Murnau, West Germany

WHAT SHOULD A SKI BOOT DO?

After Steve Podborski won the 1981-82 World Cup Downhill title using a revolutionary dorsal fit technology I developed for his ski boots in June of 1980, he proposed that we become partners in a venture to develop a new ski boot that would do for every skier what the dorsal fit system had done for him. In exchange for my creative efforts, Podborski would fund the venture up to a point after which we would try to raise funds from investors for the project.

If I accepted Podborski’s proposal (which I eventually did), I knew the we faced significant hurdles. After giving the proposal a lot of thought, I accepted Steve’s offer. Steve and I became partners in a company called MACPOD Enterprises Ltd. While I had identified some of the pieces of the puzzle, I didn’t yet know the answer to the question what a ski boot should do. But I knew that when the time came to raise money I would need to provide investors with convincing evidence that I knew the answer to this question.

Podborski’s success lent credibility to the project. But his credibility was based on his subjective assessment supported by his race results. To be credible, a ski boot design based on principles of science would need to be supported with data from actual skiing maneuvers that could generate meaningful, quantifiable metrics for such things as balance and ski control. When the metrics were compared to the same metrics from data captured from the same skiers using conventional ski boots, they would need to unequivocally demonstrate superior performance of the MACPOD ski boot. I had to come up with a format that would satisfy potential investors that the new ski boot MACPOD would develop would be at least as good, if not better, than the system Podborski used to win the 1981-81 World Cup Downhill title. Whatever format I came up with had to be capable of allowing investors who skied to ski in it.

In 1992, MACPOD raised money from investors to fund the first phase of the venture. The pressure was on.

The single variable assessment protocol

The factor that convinced Podborski of the merits of my dorsal fit system was the comparison test he did against identical Lange boot shells fit with conventional Lange liners.

After rupturing his ACL testing skis at the end of July in 1980 Steve went to France 2 weeks before the opening downhill race of the 1980-81 World Cup season at Val d’isere to be with the team to support them. He had not planned on skiing, let alone racing, because he had been told by his doctors he was out of commission for the 1980-81 World Cup Downhill season. But Podborski had brought 2 pair of identical Lange boot shells to France with him just in case. One pair had the untested dorsal fit system with only the upper cuff of a Lange liner mounted on the boot shaft. The other pair had conventional Lange liners.  The only difference between the boots was the fit system; the classic single variable assessment protocol.

The graphic below from my US Patent shows a conventional tongue format (20) in FIG 3 (prior art) compared to my dorsal fit system (30) in FIG 5. The shin component (31) is like a conventional tongue.

On a whim, Podborski decided to see if he could ski in the boots with the dorsal fit system. He was amazed to find that he could ski well with little pain in his partially healed, reconstructed ACL. But when he tried to ski in the boots with the conventional liner he could barely ski.  I found this interesting because the impetus for the new fit system was my hypothesis that dorsal loading of the bones of the midfoot might reduce strain on the knee by dampening decompression of the arches resulting from perturbations in ground reaction force due to asperities and undulating terrain. A conventional liner could not be used because it would have interfered with the interface of the lower shell overlap closure on the upper surface of the dorsal fit system required to apply force to it. Fig 9 below from the patent shows how the overlap of the shell applies force to the upper surface of the dorsal fit system. The buckle closures allow the force, which should be minimal, to be regulated.

The ability to compare the dorsal fit system against a conventional liner system on the same day and in same conditions made the superiority of the dorsal fit system apparent. The unprecedented improvement in performance with no run-in period or special training program strongly suggested that the improvement resulted from reducing factors in conventional ski boots that limit or degrade human performance. This experience caused me to undertake a critical analysis of the functional requirements of the human system for skiing. This exercise opened the door to the possibility of technologies that would integrate external appendages such as skis and skate blades with the human system, what I later came to term Bio-Integration.

Bio-Engineering

If structures of ski boots, ice skates and cycling shoes can limit or degrade the human performance of the user it also became apparent to me that it might be possible to modify the function of the feet and lower limbs that would make it specific to activities such as skiing, skating or cycling and even potentiate neuromuscular function. I termed this concept Bio-Engineering. I didn’t realize until 1991 that the dorsal fit system used principles of Bio-Engineering.

The graphic below is the pressure image of the right foot of an elite cyclist showing the forces applied by the foot to the sole of the shoe on the pedal spindle at 3 o’clock in the stroke sequence at a low cadence with a moderate to high load on the crank. The cyclist is wearing a conventional rigid sole cycling shoe with no arch supports, wedges or other accessories.

Red is highest force. Dark blue is the lowest force. Forces were recorded with a Tekscan F Scan system fit to the shoe.

The highest force is applied under the ball of the great toe and the great toe and to a lesser extent, the second, third and fourth toes. The dashed line shows the approximate location of the pedal spindle which is the source of resistance/reaction  force. This pressure pattern is typical of elite cyclists. Ideally, the highest force should be applied across the width of the pedal spindle by the heads of all five metatarsals. Note that aside from the high pressure patterns on the ball of the foot and toes 1 through 4 the pattern is diffuse across the heads of metatarsals 2 through 5 and under the heel.


In my next post, I will show a pressure pattern of the same foot in the same position with a technology that Bio Engineers the foot and lower limbs and discuss the significant differences.

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

ZEPPA-DELTA ANGLE EXTENDER

The problem associated with measuring boot board (zeppa) and/or binding (delta) ramp angle as individual components is that the resulting angle may not accurately reflect the actual angle between the plane of the base of the upper surface of the boot board and the base of the ski in the boot/binding/ski system. Boot boards of the same zeppa angle may not necessarily have the same zeppa angle with the base of the boot shell due to design and/or manufacturing variances.

A level inserted into a ski boot shell with the boot board in place can be difficult to read. With the liner in place, this is not a viable option. A better option is to extend the angle of the boot board up above the top of the shaft of the boot so it can be accurately and easily read.

A simple device for this purpose can be made for about $25 with basic hand tools and a few screws using 2 – 8 in (20 cm) x 12 in (30 cm) x 1/8 in (3 mm) thick steel carpenter’s squares.

Place the long arms of the squares over each other as shown in the photo below and clamp them securely together. Two-sided tape can be used to help secure the alignment. Then drill a hole  at one point on the vertical leg and screw the 2 squares together.

Check the parallelness of the 2 opposite arms on a level surface with a digital level. If good, secure the 2 levels together with a second screw. Then affix a section of 3/4 in (2 cm) x 3/4 in (2 cm) square or L-bar bar on the top of the extender to rest the level on.

To use the extender, place a boot shell on a hard, flat, level surface. If the surface is not level it should be leveled before the extender is used.

The photo below shows the extender being used to measure the zeppa angle of an old Salomon SX-90 shell. I didn’t have the electronic level for the photo. So I used a small torpedo level.

Insert the lower arm of the device into the shell as shown in the right hand image and place the lower arm firmly on the boot board. Place the level on the top arm and read the angle.

The photo below shows the same process as above. But in this example, the liner is in place. If an insole is in the liner, it should be flat with no arch form. I highlighted the square bar with pink to make it easily visible.

A check of the zeppa-delta angle of the boot-binding-ski system can be done by mounting the boot in the binding of the ski that is part of the system and clamping the ski to a flat surface with sufficient force to ensure the camber is removed and the running surface of the base is in full contact with the supporting surface. A strap wrapped over the front of the boot shell and under and around the supporting surface then tensioned will help ensure that the toe plate of the binding is loaded.

The Zeppa-Delta Angle Extender provides the user with a fast accurate way to know their total number. What’s yours?

 

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.