custom orthotics


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.






Almost 40 years ago to the day, the head of the Whistler Pro Patrol, whose boots I had worked on, introduced me to Nancy Greene in the Roundhouse restaurant on top of Whistler Mountain. The rest is, as they say, history. Nancy asked me if I would work on her ski boots. She was so impressed by the results of my work that she approached the National Ski Team to make arrangements for me to work with some of Canada’s best racers.

Recently, while going through some archived files, I found copies of Nancy’s communication with the Program Director of the National Ski Team, Andrzej Kozbial. When Nancy approached me about working with our National Team, I stressed to her that I did not see any potential arrangement with the team as a job opportunity but instead as a vehicle where I could gain further experience and knowledge while providing a crucial service to the team and furthering the sport of skiing.

The graphic below is an excerpt copied from Nancy’s first letter of April 26, 1978 to the National Ski Team Program Director.

At the time that I wrote my US Patent 5,265,350 in early 1992, the intent and purpose of the detailed and lengthy specification was to provide a repository of the knowledge I had acquired to date to serve as a legacy for skiers and skiing to help advance the sport. While this information was in support of the inventions disclosed in the patent, the majority of the information was not subject to protection under the terms of the patent. The information was open access to the world. This was my intent.

In spring of 2000, I formed a company with 2 partners for the 2000-2001 ski season called Synergy Sports Performance Consultants Ltd. The objective of the venture was to gain further experience and knowledge and create a model that could be used as a template for future skier performance programs.

The following series of graphics are from Power Point presentations synergy made to ski schools.

The following graphic is the poster that described the synergy 5 Step Performance Program.

5 Step Performance Program description

The synergy Analysis Program looks at how your body interfaces with your ski equipment; primarily your footbeds and boots because this is the connection to your equipment and through it to the snow.

Synergy offers the program as a package made up of 5 components. They can either be taken as the complete package [recommended], several components or steps at once, or one component at time. Synergy recommends that you begin at step 1 and follow the sequence in numerical order. But the order can be arranged however you wish to suit your needs. The choice is yours.

1.Biomechanical Assessment

Good foot function is the key to control. That’s why the first thing we thing we assess is your biomechanical function. What that means is that we look at how well your foot and lower limb works. The examination is done by a podiatrist who looks at how your foot functions and how the lower limbs all connect.  Then we see how effectively your feet interface with the ground by putting you on insoles that read the pressures under your feet. We coach you through some balance movements while we watch how your foot functions while our computer records the results

2. Footbed Assessment

Footbeds can have a positive, neutral or negative effect on the function of your feet.

That’s why the next thing we check is how your foot interfaces with your footbed or orthotic.  We make sure that it allows your foot to function as well as it should without one.  And if your foot needs some assistance for optimal function we make sure the footbed is helping your foot do what it needs to do.

3. Ski Boot Assessment

Now that your foot is functioning optimally we make sure your ski boot lets it keep functioning. We conduct a thorough examination of your boot and provide you with a report that tells you how your boot is affecting your performance. Most important, we tell you what has to be done to fix the problem.

4. Kinesthetic Training

Skiing is about making the right moves. Kinesthetic Training is next. It teaches you how to tell when your body is making those moves. What is Kinesthetic Training? In simple terms it means to train your body to associate a feeling or sense with the right movements made at the right time. It is feeling and bringing about an awareness so you know when you are doing it right because we have taken you there and you have felt it. A picture may be worth a thousand words, but in skiing a feeling is worth a thousand pictures. We bring you to understand what you should feel in your foot at the start of the turn and then what it feels like to settle and balance onto the foot that drives the ski. By acquiring this sense you become more aware of how to allow your foot to transfer energy directly to the edge of the ski by using the body the way it was designed to be used. Remember, your body was not made to be a lever.

5. On-Hill Data Collection

This is where everything comes together. We move to the ski hill for this part of the package. We meet up top on Whistler or Blackcomb Mountain. We put our pressure insoles in your ski boots.  A pair of cables from the insoles goes up your ski pants where it connects to the data box [a kind of mini computer] we attached to your waistband.  Then we go out for a run on moderate, groomed terrain.  We record data in three takes in medium radius turns at a speed you are most comfortable with. While this is happening we videotape your skiing. Then we head into the lodge and synchronize the video with your foot pressure data. When this is done we watch your foot function in your boots on the computer screen on one side while we study your ski video on the other side of the screen. This way we confirm that your foot is functioning optimally as confirmed by analyzing your movement patterns and the timing of your skills.

My next post will be on the synergy Boot Assessment program.



There are some who can benefit from footbeds or orthotics and some who do actually need them. But these groups are the rare exception. And they are unlikely to be skiers.

Orthotics. The pros / cons of orthotics in today’s society!

In a recent YouTube video (1.), Podiatrist & Human Movement Specialist, Dr Emily Splichal, explores the concept of orthotics and their role in today’s society. Dr. Splichal doesn’t pull any punches when she says:

“…..I have been through the conventional podiatric school and been fed pretty much the bullshit from podiatry of how every single person needs to be in orthotics, that our foot is not able to support itself without orthotics……if we do not use orthotics our foot is going to completely collapse  and you are going to lose your arch…….”

“……Our foot is designed to support itself. If we actually needed orthotics, we would be born…..we would come out of the womb, with orthotics on our feet.”

Meantime, The Foot Collective  asks (2.) Are you promoting weak feet?

  • Anything you use for artificial support at the feet (footwear with arch support & orthotics) your brain takes into account and accommodates for it.
  • That means if you provide your foot support your brain shuts down the natural arch supporters to reduce un-necessary energy expenditure.
  • Stop using support to help with pronation and understand why your feet pronate in the first place – because they are weak.
  • Strong feet = strong foundation = strong body.

The Real Source of Support for the Arch

Ray McClanahan, D.P.M. offers a perspective on the issue of Arch Support in his post on the CorrectToes blog (3.)

Are Custom Footbeds and Orthotics better than stock insoles?

In his post of August 20, 2017, Custom Foot Orthotics; No Better Than Stock Insoles (4.), Rick Merriam, of Engaging Muscles, explores the issue of orthotics in depth.

Prior to being told that supportive insoles are the way to go, I think it’s safe to say that all of those people didn’t know what they didn’t know.

The erroneous assumption that every skier needs footbeds or orthotics was made at a time when little  was known about the function of the foot and lower limb, especially in late stance. I was one of those who didn’t know what I didn’t know when initially when down the ‘the foot needs to be supported in skiing’ road up until I realized what I didn’t know and took steps to acquire the requisite knowledge.

Footbeds; is anyone checking what they do?

In 2000, I formed a company called Synergy Sports Performance Consultants (5). Synergys’ product was high quality information. One of my partners, UK Podiatrist, Sophie Cox, was trained by Novel of Germany and was one of the few experts in the world at that time on the Pedar system. Synergy did not make and/or sell footbeds or orthotics. Instead, we checked the effect of footbeds on skier performance. We performed a quick footbed check for a minimal fee of $20 using the sophisticated Novel Pedar pressure analysis technology.

Synergy was one of the first companies in the world to use the Novel Pedar pressure analysis system synchronized to video to acquire data on skier performance and analyze the captured data.  The Synergy team with diverse expertise studied the effect of ski boots and custom insoles on skier performance and identified functional issues in the body that needed to be addressed. It was a common finding that custom footbeds were significantly compromising skier performance, especially the ability to create the necessary platform under the foot on which to stand and balance on the outside ski.

Synergy offered a comprehensive 5 Step Performance Program that started with a footbed check. A key component was item 2., the Biomechanical Check.

With increasing recognition of the negative effect of most footwear on the user and criticism of the unproven claims made for footbeds and orthotics coming hard and fast, credibility in skiing is rapidly going downhill. It is time for proponents of custom insoles for ski boots to support their claims with solid evidence, especially evidence supported with data acquired during actual ski maneuvers. The technology to do this has existed since at least the year 2000.



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.




There is currently a whole series of Foot-Cast Episodes on The Foot Collective site at –


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.



Two factors can prevent a skier from being able to develop a platform under the body of the outside ski on which to stand and balance on during a turn using the same processes used to balance on one foot on solid ground:

  1. The biomechanics of the foot and leg have been compromised by traditional footwear and,
  2. The structures of the ski boot, especially insoles, footbeds, orthotics and form fit liners, are interfering with the foot to pelvic core tensioning of the biokinetic chain that starts in the forefoot.

The torsional stiffening of the ankle and knee joints resulting from fascial tensioning of the biokinetic chain is fundamental to the ability to create a platform under the body of the outside ski by internally rotating the outside leg from the pelvis. It may sound complicated. But it is actually quite simple. Once learned, it can become as intuitive as walking.

The best method I have found to appreciate how ski boots, custom insoles and form fitting liners can affect the function of the feet and even the entire body, is do a series of exercises starting with the short foot. The short foot helps to assess the ability to harness the Windlass Power associated with the big toe. Once proper function has been acquired in the foot and leg, a skier can go through a methodical, step-by-step process to assess the effect of each component of the ski boot on the function of the feet and legs.

The latest edition of Runner’s World (1.) reports on a study done by a team at Brigham Young University that compared the size and strength of the foot’s “instrinsic” muscles in 21 female runners and 13 female gymnasts. Gymnasts train and compete in bare feet.

The researchers found:

Of the four muscles measured with ultrasound, the gymnasts were significantly bigger on average in two of them, with no difference in the other two. The gymnasts were stronger in their ability to flex their big toe, with no difference in the strength of the second, third, and fourth toes.

Although balance is important in all sports, it is especially critical in gymnastics. So it is significant that study found that the big toes of the gymnasts were stronger than the big toes of the runners.

Until recently, I found it much easier to balance on my left leg than my right leg. The big toe on my left foot was noticeably larger than the big toe on my right foot and the big toe on my left foot was aligned straight ahead whereas the big toe on my right foot was angled outward towards my small toes. This misalignment had pushed the ball of my foot towards the inside of my foot causing a bunion to form on the side, a condition known as hallux valgus. I now understand why I could balance better on my left foot than my right foot.

The muscle that presses the big toe down is called the Flexor Hallucis Longis (FHL). It is inserted into the last joint of the big toe where it exerts a pull that is linear with the big toe and ball of the foot. When the arch is maximally compressed in late stance, the Flexor Hallucis Longis is stretched and tensioned causing the big toe to press down. It’s insertion on the upper third of the fibula causes the lower leg to rotate externally (to the outside). When stretched, the FHL acts in combination with the Posterior Tibialis to support the arch. Footwear that prevents the correct alignment of the hallux weakens the arch making it more difficult to balance on one foot; the foot pronates unnaturally.

Going mostly barefoot for the past 10 years and wearing minimal type shoes for the past 6 years, made my feet stronger.  But it had minimal effect in correcting the hallux valgus in my right foot. It was only after doing the exercises in the links that follow, such as the short foot, that the big toe on my right foot became properly aligned and grew in size. It is now the same size as my left toe and I am able to balance equally well on both feet. The problem with ski boots and most footwear, is that they can force the big toe into a hallux valgus position while preventing the forefoot from splaying and spreading naturally weakening the arch and significantly impairing natural balance.

In the early 1970’s, when the then new plastic ski boots were making a presence in skiing, research on human locomotion was in its infancy. Studies of the effects of sports shoes on human performance were virtually nonexistent. The only technology available back then with which to study the biomechanics of athletes was high speed (film) movies. Ski boot design and modification was a process of trial and error. Many of the positions that predominate even today were formed back then.

As methodologies began to develop that enabled the study of the effect of sports shoes on users, biomechanists and medical specialists became convinced that excessive impact forces and excessive pronation were the most important issues affecting performance and causing or contributing to injury. I suspect that biomechanists and medical specialists arrived at this conclusion even though there was little evidence to support it because it seemed logical. Soon, the term, excessive pronation became a household word. The perceived solution? Arch supports, cushioned soles, motion control shoes and a global market for arch supports.  This appears to have precipitated an assumption within the ski industry that the feet of all skiers needed to be supported in ski boots and pronation, greatly restricted, or even prevented altogether. Even though no studies were ever done that I am aware of that demonstrated that pronation was a problem in skiing, support and immobilization became the defacto standard. Custom footbeds, orthotics and form fitted liners became a lucrative market.

As the support and immobilize paradigm was becoming entrenched in skiing, studies were increasingly concluding that, with rare exceptions, excessive pronation, is a non-existent condition with no pathologies associated with it and that the role of impact forces was mis-read. Today, it is increasingly being recognized that interference to natural foot splay and joint alignment of the big toe by the structures of footwear, causes weakness in the foot and lower limbs through interference with the natural processes of sequential fascial tensioning that occurs in the late stance phase. But the makers of footwear and interventions such as arch supports, have been slow to recognize and embrace these findings.

A key indicator of whether a skier has successfully developed a platform under the outside ski with which stand and balance on, is the position and alignment of the knee in relation to the foot and pelvis as the skier enters the fall line from the top of a turn. I discuss this in my post, MIKAELA SHIFFRIN AND THE SIDECUT FACTOR.

Best Surfaces for Training

A good starting point for the short foot and other exercises is Dr.Emily Splichal’s YouTube video, Best Surfaces for Training

Although it may seem logical to conclude that soft, cushioned surfaces are best for the feet, the reality is very different. The best surfaces to balance on are hard, textured surfaces. Dr. Splichal has recently introduced the world’s first surface science insoles and yoga mats using a technology she developed called NABOSO which means without shoes in Czech.

The skin on the bottom of the foot plays a critical role in balance, posture, motor control and human locomotion. All footwear – including minimal footwear – to some degree blocks the necessary stimulation of these plantar proprioceptors resulting in a delay in the response of the nervous system which can contribute to joint pain, compensations, loss of balance and inefficient movement patterns. I’ve been testing NABOSO insoles for about a month. I will discuss NABOSO insoles in a future post. In the meantime, you can read about NABOSO at

Short Foot Activation


Short Foot Single Leg Progressions

  1. Here’s the Latest Research on Running Form – May 30, 2017
  2. Biomechanics of Sports Shoes – Benno M. Nigg


In this post, I am going to discuss the process I follow to assess what I call the essential foot to shell clearances. This is a 2-step process.

Step 1 – Establish the clearances between the structures of the foot and the inner wall of the boot shell required for the foot to function.

Step 2 – Establish the physical connections between discrete restraint force transfer areas of the foot and the inner walls of the boot shell required for the effective force transfer to the ski, for containment of the foot required to support the processes of balance and for the coupling of the foot to specific mechanical references in the boot shell related to the running surface of the ski.

As a prelude to discussing shell fit, it is necessary to point out that a major shift is occuring in the area of focus on the human foot.

Until recently, most discussions on the human foot have focussed almost exclusively on the rearfoot; the ankle complex, the tibial-talar and sub-talar joints, ankle dorsiflexion and plantarflexion, ankle mobility, inversion, eversion, etc. This limited focus has been at the expense of an appreciation and understanding of the role of the forefoot and the complex lever mechanism that enables the first MTP joint to apply large forces to the ground. A study (1) published in 2004 commented:

The plantar aponeurosis (plantar fascia) is known to be a major contributor to arch support, but its role in transferring Achilles tendon loads to the forefoot remains poorly understood.

 Fascia is a sheet or band of fibrous tissue such as lies deep to the skin or invests muscles or various body organs.

The most plausible reason why the role of the  plantar aponeurosis in transferring Achilles tendon loads to the forefoot is poorly understood is that it has not been given much attention until recently.  

The above cited study concluded:

Plantar aponeurosis forces gradually increased during stance and peaked in late stance.

The almost exclusive focus of attention on the rearfoot has led to assumptions about the function of the foot as a system which are only now being called into question and found to be erroneous or invalid. One result is the erroneous assumption that the arch of the human foot is weak and collapses under the weight of the body. This has spawned a lucrative market for custom made arch supports intended to provide what is perceived as needed support for the arch of the foot.

In boot-fitting, the process of fascial tensioning, in which the height of the arch decreases and the forefoot splays, has been misinterpreted as an indication of a collapsing (implied failure) of the arch due to its inability to support the weight of the superincumbent body during skiing maneuvers. This has led to an almost universal perception and acceptance in skiing of custom arch supports as essential foundations for the foot and the most important part of a ski boot.

The Fascial Tension/SR Stance Connection

Plantar aponeurosis forces peak in late stance in the process of fascial tensioning where they act to maximally stiffen the foot in preparation for the application of propulsive force to the ground. When fascial tensioning of the plantar aponeurosis peaks, forward rotation of the shank is arrested by isometric contraction of the Achilles tendon. This is the shank angle associated with the SR Stance.

Immobilize – Support – Stabilize

Discussions of foot function in the context of the foot to shell clearances necessary for foot function and especially fascial tensioning, tend to be obscured by a consistent, persistent narrative in the ski industry spanning decades that the foot should be supported, stabilized and immobilized in a ski boot. Foot splay, associated with fascial arch tensioning, is viewed as a bad thing. Efforts are made to prevent foot splay with arch supports and custom formed liners in order to the fit the foot in the smallest possible boot size in the name of optimizing support.

In the new paradigm that exists today, the foot is increasingly viewed in the context of a deeply-rooted structure. In the design and fabrication of footwear, attention is now being directed to the accommodation of the  fascial architecture  and the importance of fascial tensioning as it pertains to the science of the human lever mechanism of the foot.

Fascial Tensioning and the Human Foot Lever

Fascial tensioning is critical to the stiffening of the foot for effective force transmission and to foot to core sequencing.

The body perceives impact forces that tend to disturb equilibrium as vibrations. It damps vibration by creating fascial tension in the arches of the foot and the lower limb. Supporting the structures of the foot, especially the arch, diminishes both the degree and speed of fascial tensioning to the detriment of the processes of balance and the ability to protect the tissues of the lower limbs through the process of damping of impact forces.

Dr. Emily Splichal has an excellent webinar on The Science of the Human Lever – Internal Fascial Architecture of the Foot as it pertains to foot to core sequencing –

The DIN Standard is Not a Foot Standard

A major problem for the human foot in a ski boot is the DIN standard toe shape. DIN stands for ‘Deutsches Institut für Normung’ which means ‘German Institute of Standardization’.

The DIN toe shape creates a standard interface for bindings. In a strong, healthy foot, the big toe or hallux should be aligned straight ahead on the center axis of the boot/ski. But as an interface for the human foot, the DIN standard toe shape of a ski boot is the equivalent of a round hole for a wedge-shaped peg.

The graphic below shows a photograph of a foot overlaid over a photograph of the ski boot for the same foot. The outline of the wall of the boot is shown in red. Even though the length of the boot shell is greater than the length of the foot, the big toe will be bent inward by the wall of the shell using the one finger space behind the heel shell length check.


The Importance of Foot Splay

The progressive fascial tensioning that occurs as CoM advances over the foot transforms foot into a rigid lever that enables the plantar foot to apply force the ground or to a structure underneath the plantar foot such as a ski or skate blade. Forefoot splay is important to the stiffening of the forefoot required for effective plantar to ground force transfer.

Ski boot performance is typically equated with shell last width. Performance boots are classified as narrow. Such boots typically have lasts ranging from 96 mm to 99 mm. Narrow boots are claimed to provide superior sensitivity and quick response, implying superior control of the ski.

The outside bone-to-bone width shown in the photo below is not quite 109 mm. The boot shell has been expanded. The 2 red arrows show the 5th and 1st toe joints (metatarsophalangeal joint or MTP joint). A prime hot spot in less than adequate shell width in the forefoot, is the 5th MTP joint. Even a minimal liner will narrow the boot shell width by 3 to 4 mm.


Shell Check: Start Point 

I start with a skier standing in both boot shells with the insole in place from the liner then have them claw each foot forward in the shells using their toes until they can just feel the wall of the shell with the outside (medial) aspect of the big toe when they wiggle the toe up and down. If there is a finger space behind the heel, the shell is in the ball park.

A second check is made with the skier standing on one foot. Some allowance for the correct alignment of the big toe  can be made by grinding the inside of the shell where it is forcing the big toe inward. When fully weighted, a fascially tensioned forefoot will splay approximately 3 mm for a female and 5 mm for a male.  The ball shaped protrusion of the 5th MTP joint is typically almost directly below the toe buckle of a 4 – buckle boot.

Once a skier can stand on one foot in each shell with adequate space for normal foot splay, the rear foot can be checked for clearance. The usual sources of problems are the inside ankle bone (medial malleolus) and the navicular and/or the medial tarsal bone. A good way to locate the prime areas of contact is to apply a thick face cream or even toothpaste to the inside ankle bones then carefully insert the foot into the boot shell, stand on it to make contact with the shell, then carefully remove the foot. The cream will leave tell tale smears on the boot shell which can then be marked with a felt pen.

Getting Step 1 successfully completed can involve alternating back and forth between forefoot and rearfoot clearance. Until, both areas are right, full normal foot splay may not occur. Step 2 is done in conjunction with liner modifications which can be a process in itself and is often the most problematic aspect of creating an environment in a ski boot that accommodates and supports foot function especially fascial tensioning.

  1. Dynamic loading of the plantar aponeurosis in walking – Erdemir A1, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA  – J Bone Joint Surg Am. 2004 Mar;86-A(3):546-52.


The big epiphany I had about 1975, was that the foot needed to be supported in the new plastic ski boots and that it was a lack of support that was causing my difficulties skiing after switching from low cut leather boots to the new higher, rigid plastic boots.

Back then, I was an avid runner. As best I can  recall, it was an article in Runner’s World on running injuries caused by over-pronation that served as a catalyst for my conclusion that the foot needed to be supported in a ski boot. I assumed that what was being reported in running magazines was both factual and derived from science-based investigations. While I had not found anything in the literature that suggested that the foot needed to be supported in a ski boot, it seemed logical to me that if runners needed support in their shoes, the need for support in a ski boot was many times greater. But my conclusion was based on the assumption that over-pronation was a pathology and that it was a proven cause of injuries in running. Therefor, it was also a problem in skiing.

Pronation and over-pronation was a new concept to me in 1975. My running partners and I all ran in flats with no arch support. None of us had ever heard of, let alone experienced, knee pain or the myriad of other problems that were fast becoming an integral part of running and were claimed to be caused by overpronation.

Soon after I read the article on overpronation, I made an appointment with a podiatrist in Vancouver to have my feet examined. I was hopeful that he would find the defect(s) in my foot that were causing me difficulties in skiing in the new plastic boots. But after a thorough examination, he pronounced my feet healthy and normal. Undeterred, I made an appointment for my wife and I with a well known sports podiatrist in Seattle, Washington, almost 800 miles round trip to and from Whistler. We made a special trip to Seattle to have prescription orthotics made for our ski boots. But far from helping, they made both of our skiing worse, much worse. Still, I remained convinced that the foot needed support in a ski boot.

Between 1977 and about 1983, I made a lot of footbeds for ski boots. From the first pair of footbeds I made, I received positive feedback. Skiers loved them. Some skiers told me they would never ski again without the footbeds I made for them. Even today, I encounter skiers who are still using the same footbeds I made for them 40 years ago. Did this subjective feedback serve as evidence that my footbeds made skiers ski better? No.

By about 1989, I was still unable to understand why I was continuing to experience difficulty skiing even after trying numerous pair of plastic ski boots. At that time, I was struggling to invent and patent a ski boot based on sound principles of functional anatomy

I finally came to the realization that the only way to arrive at meaningful conclusions about how the human system should ideally function in skiing was to design and fabricate an open-architecture research vehicle, one that minimized any neural noise that was unavoidably caused by interference with the physiologic function of the user by structures of the conventional ski boot. It had become apparent to me that it is the level of ‘neural noise’ and interference to physiologic function caused by a tightly fitting ski boot that prevents anyone from proving how a ski boot affects a skier.

The Birdcage allowed the capture of data during actual ski maneuvers that showed how some of the world’s best skiers skied and especially what happened when specific joint actions were interfered with.

It was was also about 1989 that I was starting to question how an insole or orthotic fit to one ski boot could produce the same result in a different ski boot or with skis with different sidecuts, especially width underfoot and different lift heights of the sole of the foot above the surface of the snow. I was also starting to question how the same stock or custom insole or orthotic could produce the same effect when used in different shoes. A custom insole for a female might be used in casual shoes, flats, running shoes, walking shoes, hiking boots and even spiked, high heel shoes. And what happens to the effects produced by an insole or orthotic when the sole of the shoe it is used in wears unevenly?

It was obvious to me, and should be obvious to anyone, that it is impossible for an insole or orthotic to consistently produce the same effect in widely varying footwear that each affect the foot in a different way. 

Despite the many questions I was having about insoles and orthotics, I continued to believe that they had value in some applications. In the years following the Birdcage tests of 1991, my wife had two different pairs of prescription orthotics made, both by reputable labs, for issues with hip and back pain. Neither pair provided any perceivable benefit. Both pairs were eventually discarded.

The best skiing experience today for my wife and I is with perfectly flat insoles and boot boards that provide no perceivable interference with the dynamics of the arches of our feet. Even the slightest impingement is immediately perceived. All of the shoes I wear have either flat insoles or no insoles. If I purchase a shoe with an insole with arch support, I modify it to remove the support.