A key issue is where does Shiffrin, or any skier in her class, start and end a turn? I have marked the video clips in my last post with the start of the transition and the point at which Shiffrin has established a dynamically balanced base of support on her new outside foot (left ski). From my perspective, the start of the transition marks the end of a turn; in Shiffrin’s case the end of a left turn. The establishment of a dynamically tensioned base of support marks the start of a turn.
In the transition phase, Shiffrin’s skis run straight. This is one reason she is fast. She is accelerating. But more than simply accelerating, it is necessary to square the hips so Shiffrin can move her CoM forward onto the new outside foot (ski) and over the ball of the foot. This require letting the skis run straight. I will explain how and why in a future post. For now, it is important to know that Shiffrin’s left foot must be able to assume the architecture associated with a dynamically tensioned base of support in a fraction of a second.
I have never met Shiffrin, let alone seen her other that in videos. But judging by the fine features in her face and what appears to be a small boned skeleton I am confident that she has moderate width or even moderate to narrow width feet and small calve muscles in combination with structurally stiff feet. Structurally stiff feet require a small 3-dimensional envelope in which to function compared to a looser foot structure. In other words, Shiffrin has the kind of foot structure that can function reasonably well within the constraints of a tightly fit ski boot that would render someone with a looser foot structure all but dysfunctional. Having the right stuff in the feet and legs enables a skier to start to make the Ski Move in their formative skiing years and continue to refine it.
Here’s a superimposed view of the end and start of Shiffrin’s left hand turn as shown in the second turn clip.