If you are like most, you probably assume that the design of ski equipment, especially ski boots, is based on sound principles of science, and that products are thoroughly tested for their effect on the user. After all, attaching a ski to the foot dramatically alters its shape and form and especially the nature of any external forces applied to it. So it would seem both logical and reasonable that products that have the potential to significantly alter the function of the foot and lower limb would be thoroughly evaluated and tested. But if you thought they were, you would be wrong. A recent paper, Materials, Designs and Standards Used in Ski-Boots for Alpine Skiing (October 21, 2013) states, “Despite the large market of ski equipment, not many scientific papers have been published on this subject in the past.” – Sports 2013, 1, 78-113; doi:10.3390/sports1040078. So how is equipment tested? According to the paper, “The development of alpine ski equipment has been done, in the beginning, mainly by trial and error, using on-snow tests.” Although materials and methods used in the design and manufacture of ski equipment have significantly advanced in recent years, the testing of new boots and skis appears to have remained largely subjective. A company comes out with a new boot or ski format or an accessory like Jet Stix and industry skiers try to come up with the best way to use it through on-snow testing. When shape skis were introduced, the pure carved turn was promoted as the new way to ski. In the order of things, the product comes first, learning how to use it follows. The latest innovation of equipment makers seems to be accepted and embraced without question.
In reviewing the history of ski boots over several decades, every possible format has been tried; low cut leather boots, low cut plastic boots, high cut plastic boots, knee high boots, lever boots, soft boots, top entry, side entry, rear entry, you name it, it has been tried (https://en.wikipedia.org/wiki/Ski_boot). Was any consideration ever given as to the effect these formats had on the end user or whether they made skiing unnecessarily difficult? As far as I can tell, the answer is no. The ski industry model appears to be based on the industrial mass production model wherein the end objective is ‘the least product for the most money’. In this model, ski equipment, ski teaching methodologies and, to a lesser extent, race coaching, are predicated on paint-by-number processes and averages, not individual skier needs.
My early attempts to improve the fit (reduce the looseness) of my own ski boots were limited to the established practice of adding foam or felt pads to liners adjacent the ankle bones and around the heel to tighten the fit. Fitting was a very general concept that mostly involved adding padding to liners, not removing it. When foamed-in-place and thermoformable liners were introduced, the narrative became focussed on the perfect fit of the ski boot with every nuance of the foot and leg. It was in the spring of 1978 that I first became aware of claims emerging within the ranks of the ski industry that the foot functions best in skiing when its joints are immobilized in neutral within a ski boot. Neutral in this context refers to the position of the subtalar joint of the ankle wherein the subtalar joint is neither pronated or supinated. As acceptance of the neutral STJ paradigm grew, claims began to emerge implying that pronation was detrimental to skiing and could result in potentially injurious stress. I made a concerted effort to find explanations based on principles of applied science and/or studies that supported these claims. But my efforts failed to turn up anything significant even with the considerable resources of the National Research Council of Canada behind me. Where did these theories (they were exactly that) come from? Was there any rationale, let alone science behind them? Not as far as I could tell.
The ability to assume what I refer to as the SR Stance on skis is the prerequisite to the development of a solid technique. The single greatest factor influencing the ability to assume the SR Stance is the ski boot and especially any interventions introduced that influence the function of the foot and lower limb. Many of the widely accepted and promoted things that are done to the foot with a ski boot appear to have little or no support in principles of science. This is particularly true of interventions whose objective is to limit pronation or immobilize the joints of the foot in neutral.
The most likely roots of the neutral theory is The Biomechanical Examination of the Foot, Volume 1 by Merton Root, DPM and associates, DPM. Published in 1971, the book describes a set of eight “Biophysical Criteria for Normalcy,” which Root and associates ‘considered’ to be ideal values for normal foot function. Although the position of what is normal does not appear to be supported by studies, a definition of normal by a prominent podiatrist like Root inferred that feet that failed to meet Root’s criteria of normal required corrective interventions such as orthotics. Many podiatrists still commonly use these criteria to determine whether a foot is normal even though scientific research has never shown the biophysical criteria for normalcy that Root and coworkers proposed over three decades ago to be either ideal or an average range of foot and lower extremity structural parameters within the healthy human population.
According to Roots standards of normal, when a subject is standing on two feet (bipedal stance) with the weight of the body evenly distributed between both feet, the distal third of the leg should vertical to the supporting surface, the subtalar joint should rest in its neutral position where it is neither pronated or supinated and the calcaneal (heel bone) bisection should be vertical. Roots’ criteria of normal was meant for assessment purposes during an examination of the foot with the subject standing in a static position. To the best of my knowledge, Root never made any statement or claims to the effect that the foot functions best when its joints are immobilized in neutral, only that in a static examination position with the subject in bipedal stance, the subtalar joint should rest in its neutral position. It appears that the static examination definition of normal somehow morphed into the best functional configuration for skiing. From a functional perspective, it is a contradiction in terms to state that human foot, as one of the most dynamic structures in the body, will become optimally functional when it is rendered completely dysfunctional. If this were true, why stop at the foot? How about total body encapsulation?
The central issue, which everyone seems to be avoiding, is the process by which the 2 principle forces acting on a skier become aligned in opposition with each other utilizing ground reaction force from the snow to generate solid support between whole sole of foot and ground (snow). Everything else is just fluff. So why hasn’t this issue been addressed? Perhaps no one has been able to figure it out.