Since the end of ski season is rapidly approaching in many parts of the world, I am going to do a series of posts on the modifications that I typically make to my ski boots that allow my lower limbs to function for skiing. The best way to appreciate my position on the biomechanics of lower limb function required for effortless skiing is to experience it. But experiencing what I experience requires a functional environment for the foot and leg within the ski boot.
Contrary to what some ski magazines and boot-fitters would have people believe, ski boots do not function. They are inanimate objects. In my US Patent No. 5,265,350 I go into great detail on the structural aspects of a ski boot required to create a functional environment for the foot and leg. While it is possible to apply the information contained in the patent to a conventional ski boot, the intent was to apply it to the design of an entirely new ski boot. If you want to ski like Ligety, Shiffrin or any skier who engages the external forces to drive their outside ski into a turn you need to have ski boots that allow the same 3-dimensional movements of the elements of the foot and leg that they use. But the reality is that without a foot and leg shape that is compatible with the internal constraints typical of most rigid ski boot shells the task of finding and modifying a boot is made more difficult.
Here are some excerpts from my US Patent No. 5,265,350 on the problems with conventional ski boots aka the prior art.
The (joints of the) foot articulates in order to facilitate muscle function. Muscles respond in opposition to loads imposed upon the foot. A process ensues wherein the chain of articulations, initiated at the foot, are continuously mobilized so as to maintain a state of balance.
COMMENT: This is an immutable principle that for some reason ski boot designers and boot-fitters seem to ignore.
Existing footwear (i.e. the conventional ski boot) does not provide for the dynamic nature of the architecture of the foot by providing a fit system with dynamic and predictable qualities to substantially match those of the foot and lower leg.
Although somewhat vaguely stated, a generally accepted theme has arisen over the years, one of indiscriminate envelopment and “overall restraint” applied to the foot and leg within the footwear. The stated position of various authorities skilled in the art of the design and fabrication of footwear for skiing is that the foot functions best when movement about its articulations is substantially prevented or restricted.
To serve this end, inner ski boot liners are usually formed around inanimate lasts or, alternatively, the foot and leg are inserted into an inner liner within the ski boot shell and foam is introduced into a bladder in the liner so as to totally occupy any free space between the foot and leg and the outer ski boot shell. The outer shell of the footwear is closed around this inner envelopment forming an encasement with which to secure and substantially immobilize the foot and leg. This is considered the optimum and, therefore, ideal form of envelopment. The perspective is that the physiologic structures of the foot are inherently weak and thus, unsuited for skiing. Enveloping the foot within an enclosure which makes it more rigid is thought to add the necessary strength with which to suitably adapt it for skiing. The reasoning being, that the foot and leg now having being suitably strengthened, can form a solid connection with the ski while the leg, now made more rigid, can better serve as a lever with which to apply edging force to the ski. To some degree, the prior art has acknowledged a need for the ankle joint to articulate in flexion. However, the prior art has not differentiated exactly how articulation of the ankle joint might be separated from the object of generalized and indiscriminate envelopment and thus made possible. Therefore, the theme of prior art is inconsistent and lacks continuity.
COMMENT: The reality is that ski boot designers and boot-fitters have no definitive idea of how the function of the foot and lower limb as a whole is impacted when a skier clamps their foot inside the confines of a rigid plastic ski boot. The effect may be quite different from one skier to another and even between the left and right feet of the same skier. And it can and does change from one ski day to another. Hence the reference in my patent to indiscriminate envelopment and overall restraint. This is an important point because the tacit assumption on which most ski teaching and coaching methodologies are based is that skiing like the best skiers is a simple matter of watching and copying the best. This ‘theory’ is complicated by the fact that what expert skiers, including ski pros, coaches and even the world’s racers, say they are doing and what they are actually doing can be two very different things.
In my first year on skis in low-cut leather boots I distinctly recall watching in awe as expert skiers skied effortlessly on icy slopes, their edges gripping the slippery surface like magnets. Even though I skied with ease and could make elegant parallel turns on powdery snow, I could not hold an edge on ice. Among the explanations offered by the experts for my ineptness; my boots weren’t stiff enough, my edges weren’t sharp enough, I needed more practice or I lacked the athletic ability. None of these explanations helped. One explanation that made sense to me was that the experts, who could hold on ice, established ‘an early edge’. But no one could explain how they did this. It was considered mystical, beyond explanation. The new rigid plastic boots promised universal edge hold for all skiers. But they not only made edging harder for me, they made skiing in general harder, much harder. By about 1985 I began to observe what I came to call the Ski Move. It was subtle. But it was clear to me that the expert skiers who skied with incredible ease and finesse were making different moves than lesser skiers. If this subtle move made skiing incredibly easy for a select few why wasn’t everyone doing it? What I eventually discovered was that for most skiers it wasn’t possible for them to make the Ski Move because their ski boots would not let them.
In my next post I will talk about what Ligety, Shiffrin, Vonn and the rest of the world’s best skiers have in common; the right foot and leg shape and structure.