In order to know what to look for, one has to first have a theory that explains what is happening. In order to see what I see, one needs to know something about my theory and how I validated it. With all due to respect to Ted Ligety, in order to fully leverage the potential of the technique he is using, it is necessary to know the basic theory and especially the working principles behind it. Although I could wrong, based on the NY Times video, it is questionable whether Ligety fully understands all the relevant issues associated with the technique he using. Here is one thing that he gets full marks for.
Ligety: “I step on the new (uphill) ski while it is still on the edge it was currently on in that turn (ergo the uphill edge).”
The question is why is this so important? The answer is that Ligety needs to initiate what I call the pronation flow when his uphill ski is still on its uphill edge. In addition, he needs to initiate a movement sequence that rotates his uphill foot into a foot flat position on the slope. In other words, Ligety (and Shiffrin) need to momentarily literally stand on the slope of the hill. Three things make this possible, 1) extension, 2) pronation and, 3) momentum. Momentum is tending to keep Ligety’s C0M travelling along a fixed path. Gravity is tending to pull Ligety’s CoM down towards the centre of the earth. Ligety and Shiffrin both push back against momentum and gravity by extending their uphill leg with muscle force. While it may not be obvious from the camera angle of the photo below, Shiffrin is literally standing on the slope of the hill. Although the photo is blurry, you can see that she has started to pivot her left ski across her trajectory. Shiffrin is approaching maximum extension of her left leg. She will extend it further in conjunction with the pivoting of her foot in order to maximize the loading of forces into the turn. Ligety loads his ski more than Shiffrin through the timing of his extension.
There are several reasons why no one has figured out what Hess, Ligety Shiffrin and in fact all the world’s best skiers have been doing for decadeas. The main reason for the inability to see is that everyone has been focussing their attention on where the action is, at the apex of the turn where the outside ski is maximally loaded. Once the prevailing wisdom saw the downhill ski of the turn as the outside ski they were blinded in terms of the ability to see what the best skiers were doing. The prevailing mentality became to maximize the loading of the outside ski at the apex of the turn. The video below of Guenther Mader in 1987 shows the maximum loading technique. Mader literally pounces on his outside ski and uses the reaction force to catapult him into the next turn.
Loading the outside ski of a turn was the right idea. But the mechanism was wrong. It could not possibly work because the Centre of Pressure under the sole of the foot in the technique Mader is using is on the outside turn aspect of the inside edge of the outside ski. In this configuration, loading the outside ski will tend to push to foot to the outside of the turn and rotate it and the leg (more on this later) away from the turn. These issues led to further serious errors. Trying to fix the foot in neutral and attempts to use the leg as a lever to hold the ski on edge. Today, a whole industry is working 24/7 trying to make it impossible for skiers make the same Ski Move that Ligety and Shiffrin make.
By the time I saw Hess in 1987, I knew that the world’s best skiers were making a move that pushed the Centre of Pressure on their uphill foot from under the heel to under the ball of their foot and kept it there through the apex of the turn. The only mechanism with which to move Centre of Pressure to the ball of the foot is pronation. The pronated configuration associated with the Ski Move allows the leg to absorb energy while enabling the injury defence mechanism to be active.
By 1990, I had formulated a hypothetical model of the mechanics, biomechanics and physics of skiing that predicated that, among other things, the world’s best skiers would move Centre of Pressure to the ball of the foot of their outside ski prior to pivoting the ski and that if the associated movements were impeded technique would be degraded. In order to test this hypothesis we did studies in 1991 using the instrumented data capture device shown in the photos below. The device replaced the conventional ski boot. It recorded the 3-dimensional internal forces applied by the foot and leg of the skier to the interfaces of the device during actual ski maneuvers as well as degrees of cuff movement. Data was acquired through 17 data channels. After only a few runs, a technician in a tent could assess the quality of the turns of a skier was making based purely on real-time, unfiltered data flow. In a future post, I will present and discuss the data. For now, it is suffice to say that the studies confirmed my Ski Move hypothesis.
That is Steve Podborski’s foot in the device in the lower right hand photo. Testers, who ranged from World Cup Champions and Olympic medallists to neophytes, reported that the device was the best ski boot they had ever skied in. US Patent No. 5,265,350, a document of almost 200 pages, was based on the results of these studies. The focus of this patent, which was granted internationally, is structures of a ski boot that permit the user to assume a dynamically balanced based of support on one foot and use it to move to a dynamically balanced based of support on the other foot. In other words, to allow the average recreational skier to make the same efficient, effective Ski Move that Hess, Ligety, Shiffrin and other elite skiers use.