BOOT FLEX CAN BE A REAL TURN OFF


The title refers to the ability of the shaft of a ski boot to disrupt and contaminate the neuromuscular processes of balance and, in particular, to diminish or extinguish the contraction of muscles that would normally act to oppose forces that tend to disturb balance. As a prelude to discussing the measures that I use in my ski boots to mitigate these effects I will address the widespread perception among ski professionals and coaches that the ski boot does not signficantly affect skier performance.

Although the design of the modern rigid plastic ski boot has some serious shortcomings, the fact of the matter is that some skiers can ski reasonably well in these boots. It is also a fact that many World Cup and Olympic medals have been won on them. This has spawned the erroneous assumption that if a skier is having problems with their skiing skills the problem lies with them, not their equipment and especially not their ski boots. The reasoning of many ski professionals and coaches is that if they can  ski without apparent difficulty in stock ski boots then acquiring skill in skiing is a simple matter of technical training and practice.  Unless one regressed, as I did after switching from low-cut leather boots in which I was an expert skier to higher, rigid plastic boots in which I was reduced to the level of a beginner, they would not have the benefit of the perspective of the ski boot as the problem. Further, until one gets very close to the optimal ski boot configuration any interference with the function of the feet and lower limbs, in particular the processes of balance, caused by the ski boot is unlikely to be perceived.

My experience with my spouses’ ski boots serves an example of how fine the line is that separates performance from dysfunction. This season I made what I thought were minor changes to her boots. But these minor changes had negative effects on her skiing far in excess of anything I could have expected. I replaced the soft fabric Lange liners in her 10 year old Head boot shells with identical new Lange liners. The reason for this change was that the old liners were disintegrating. I removed the stock Lange tongue from the new liners so she could use the tongue fit system from her old liners. But I did not cut away the seams along the sides in the front of her liner as I had done with her old liners. The reason I do this is to ensure that the metatarsals can spread under load. One significant change that I did make was to use a stock Lange insole in place of the much thinner insole in her old liners. The special tongue fit system I invented in her boots is the principal fit component. This did not change.

What happened on snow was startling.  In the first few meters of her first run my spouse went from an expert to a struggling beginner. She appeared to have little balance or control. She told me her boots felt completely wrong and that she was disoriented and could not find her balance. Her situation was so bad that we left the ski hill after one run and went home to assess the situation. After we got home I cut away most of the front of her liners. I also heated the Lange insoles and pressed them dead flat because she complained they were digging into her arch. This seemed incredible to me because the Lange insoles have almost no arch form.

The photos below show the new unmodified Lange liner on the left with the same liner modified after her skiing experience on the right. I left a small amount of the toe box of the liner to help keep the insole from creeping forward. On the left liner I also cut away some of the plastic backing of the cuff to allow her calf muscle to sit properly.

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When we went back on the ski hill the change in her skiing was dramatic and instantaneous. A similar thing happened to me with interference with the arch of my left foot. When I am in a moderate to high speed GS turn the tension in the sole  of my outside foot is so great that it feels as if my foot is made of steel and the base of support on my ski feels as if I am standing on a concrete surface. With this amount of tension anything that impinges on my arch feels like a sharp stone in my shoe. I had an interference problem in the arch of my left foot that was not addressed by shaving down an already flat insole. I eventually traced the problem to the detail of the sole of the liner that rises up along the inner aspect. Cutting away this section of the sole resolved the problem. The photo below shows the portion of the liner that was causing the problem.

Arch int

The ability of the ski boot to significantly affect skier performance was described in The Shoe in Sport 1989 – Published in Germany in 1987 as Der Schuh im Sport. ISNB 0-8151-7814-X (27 years ago). Despite the call by scientists for a ski boot based on a design that from a functional point of view that takes into consideration the realities of functional anatomy (axes etc.) a significant component of the design of ski equipment and the formulation of ski teaching and coaching methodologies continues to be influenced by opinion and subjective observation. Ski pros and coaches tend to interpret what they see in the context of what they know or what they believe they know. Although athletic prowess is arguably a factor, a significant but unrecognized factor confounding the analysis of technical faults is that the ski boot acts as a selective filter that literally determines how well someone can ski based on the physical characteristics of their feet and legs. Those who are able to ski with reasonable efficiency within the constraints of a ski boot become ski instructors. Those who ski really well become racers. The remainder languish as terminal intermediates. Levels of competition act as selective filters that eliminate those more compromised by the constraints imposed by their ski boots. Ski pros and coaches tend to view their charges based on a paradigm in which the ski boot has no effect on skier performance. Even today some coaches continue to argue that the in-boot technology that I invented and that Podborski used to compete and win on a partially healed knee was not a factor in this success, that it was training or some other factor.

A  book that I just finished reading, one  that substantiates my position that with rare exceptions ski teaching methods tend to overlook the effect of the boot on the skier, is Ski Simply Well by Ken Chaddock (http://www.skiwellsimply.com/). Chaddock is a local Ski Pro who teaches on Whistler-Blackcomb. With the exception of a few omissions, Ski Well Simply is simply one of the best books I have ever read on ski teaching, bar none. But while Chaddock raises the issue of cuff cant angle which is important, he appears to make the common assumption that those who read his book will be able to ski the same way he does. What Chaddock gets right, and he really gets it right, is his description of how he develops plantar tension in the soles of his feet and skis with minimal use of the cuff of the boot. Chaddock gets so much right that in a future post I will fill in the missing pieces and connect the dots he missed.

In my next post I will describe how I build a tongue that lets me ski in a minimal boot shell.

 

 

 

 

2 comments

  1. My impression of the Lange liner is that it is already very thin up in the region of the forefoot, like around the first metatarsal head. Do you really gain much by cutting it away there? As the foot flattens and spreads under pronation load, it would push into the medial padding, and compress it a little. In that case, you’d probably only gain an eighth of an inch or so by cutting it away. ???

    1. There are couple of issues which you reminded me that I should do posts on. First off, I try to position the head of the first metatarsal as close to the medial wall of the inner aspect of the shell as possible. So yes, even a mm or two counts. On hard pistes, most skiers need skis with a width underfoot (waist of the ski) of 67 mm or less. Some females with small feet need skis with waists around 60 mm. Second, boot makers make liners as much as 2 full sizes smaller than the shell length they are installed in to avoid the possibly of the liner buckling and forming a wrinkle that will dig into the user’s foot and result in a callback. There is also a marketing pitch that claims competition boots need a width of 93 mm to optimize steering of the ski and that All Mountains boots need a width of 103 mm. Total BS. There are reams of solid studies that found any restriction of width across the met heads has a significant impact on physiologic function. When we did tests with the Birdcage where we intentionally restricted width across the met heads we could turn a World class skier into a struggling beginner. In the case of my spouse’s boots, the stock Head liners were so bad that the best place I could and did find to fit them was in the nearest trash can. My spouse has what is termed a peasant’s foot, a chunky foot with squared-off toes and wide across the met heads. I can’t recall whether I had to stretch her Head boot at the met heads. I had to make so many extensive modifications that I can’t recall what I did. But the Lange boot and the Lange liner were much narrower and smaller in volume than the Head boot shell. The only opportunity to get the foot to pronate is in the very brief interval (about 1/10 second) when the ski and foot is flat on the snow during the transition from the old edge to the new edge. Like the song New York, New York, if you don’t pronate here, you can’t pronate anywhere. When I built Lange boots for National Team racers I had a stock of parts including liners. I often upsized the liner to the shell. Even then I still used a knife a lot.

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