“The support system allows proper flexion of the ankle joint while providing firm support for the bones of the mid-foot. When used in ski boots, the system gives the skier good balance and control of the boot even during fast downhill skiing.” United States Patent Number 4,534,122 – Inventor: David MacPhail
Thirty-four years ago, Steve Podborski won a Bronze medal for Canada in the downhill race at the Lake Placid Olympics. When he did, he was wearing a pair of Dynafit ski boots that I had modified. While it was also a great day for me, I was not satisfied that Steve was performing to his full potential. In my perspective on human performance, it is the often the limits of the equipment, not the limits of the athlete, that is the decisive factor in winning or losing.
In Putting the Boot to the Europeans – Part 3: A New Direction, I told how I had recommended to Steve that he change to Lange ski boots. I also had a new idea that I wanted to try. The plan was to put my new idea together when Steve came to my Whistler shop in June of 1980, then test the it against a pair of boots without the new idea and see if my new idea worked as expected. It was a good plan except that it didn’t work out. Before he could test my new idea Steve tore his ACL in Austria in July while testing new skis. After thinking he was out for the season, Pod went to France to be with the team for the opening race of the 1980-81 World Cup season. Although he had not been on snow since he tore his ACL, he decided to try the new boots to see if he could ski. The rest is, as they say, ‘history’. Steve was third in the opening race at Val D’ Isere. He would have won the World Cup Downhill title that season had he not come down with the flu before Aspen. The unusual characteristics of Steve’s style was his incredible smoothness on course and his ability to stay in a tuck in perfect balance and especially to absorb terrain changes. On course, he looked more like a Formula One driver driving a race car than a typical on-the-edge downhiller.
In the 1980-81 World Cup Downhill season, Steve was using an innovative in-boot technology that I invented and was granted a patent for. Excerpted pages from the patent document follow below. Dave Murray was the impetus for this invention.
Mur was the first National team racer I worked with. Since we lived close to each other he often ended up acting as a Guinea pig testing my new ideas. In 1978 I tried building a custom tongue for Mur by laminating thin layers of heat formable foam together and then shaping the assembly into a conventional tongue form. The finished tongue was a perfect fit to Mur’s shin and the instep of his foot. But it caused huge balance issues in that Mur had no balance on his skis. Since this made no sense to me I started reading books on the anatomy and biomechanics of the human lower limbs in an attempt to find out why. I eventually figured out what the problem was. The ankle is a gliding hinge with the centre of rotation well below the ankle bones. When the ankle joint flexes forward, the base of the shin is blocked by the static shape of a conventional boot tongue. In a future post I will describe all the problems this causes. But the main problem is that when the shin encounters a strong source of resistance, the muscles in the back of the leg turn off. This has the effect of disconnecting the foot from the leg and turning off the muscles that cross the knee joint, exposing it to stress and worse, exposing it to injury. Here is another excerpt from my patent:
Designers of ski boots intended for downhill (alpine) skiing have recognized the need to provide support for the leg, ankle and foot, but have tended to produce boots that are uncomfortable, that do not give the skier proper control, and that restrict those movements of the ankle joint that are necessary during skiing. Fore and aft movements of the leg at the ankle joint (i.e. plantarflexion and dorsiflexion of the foot) are often restricted or prevented in prior art ski boot by the boot tongue or other structure designed to restrain movements of the foot. Typically, a boot tongue extends from near the toes to the lower shin and, in order to provide good padding and support, is relatively inflexible. Such a tongue presents considerable resistance to dorsiflexion of the foot. Rather than concentrating on providing a new boot design, the inventor has studied ways of overcoming the above problems by providing a fit and support system which can find application in many ski boots of current design, as well as in other types of sports footwear.
The solution was a two component system joined by a flexible link. The forefoot component secures the foot in the ski boot in a manner that doesn’t interfere with ankle flexion. The shin portion ensures that the force applied to the boot cuff is consistent. Because the foot is secure in the boot shell, the cuff does not need to be tightened securely about the leg. This allows for correct and adequate ankle flexion to absorb the shocks of downhill skiing without disrupting skier balance.
Here are some photos of a version of the in-boot system I made for another skier. It is not exactly the same as the system Podborski used. But the concept is the same.