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http://www.epicski.com/t/7573/sequential-leg-movements
Bob 还说了啥
Good point, Nord. That simple observation actually brings out a surprising number of issues. Perhaps part of the solution lies in defining what exactly we mean by "start of the turn"--a point that we've debated well here at EpicSki in the past, and a question with many reasonable answers. In linked turns, skiing movements are cyclic and continuous. Where they "begin" or "end" is an arbitrary matter of definition. Furthermore, we have many different parts that all need to change direction, and may not all change at the same time, combined with PhysicsMan's valid point that "turning" involves either or both changing the direction something MOVES and changing the direction something POINTS (skis can "turn" without changing the direction of the skier's motion, as in a hockey stop).(Sorry, Si!) Even when both occur (most turns), these actions may not happen at the same time.
With that in mind, it is reasonable to think that a "turn" begins when a force pushes us from the side, and ends when that force ends. On skis, especially in the lower half of the turn, the force that keeps us turning results from the engagement of the edge(s) of the skis in the snow, creating a "reaction force" that causes the turn. Thus, the turn "ends" when the edge engagement ends--when the ski becomes flat enough on the snow to release its grip. And, of course, the next turn begins at the same moment (when turns are linked), as gravity can now pull the skier down the hill.
So, by this definition, the turn ends/begins when the edge of the downhill (usually) ski releases, releasing the pressure that is, literally, the force that causes the turn. But the tipping MOVEMENT that eventually results in edge release begins long before that point, just as a pole plant at the beginning of a turn represents the end of a movement that begins earlier in the previous turn as a swing. What you have observed in Maier's turns as movements toward the next turn of the hips and shoulders (obvious in frames 3 and 4) takes place clearly PRIOR to the edge release of his downhill (right) ski, although equally clearly, the edge angle of that ski decreases in these frames too. The downhill ski is still very much pressured, bent, and carving a left turn in the fourth frame, even as Maier moves out of that turn toward the next.
In the fifth frame (top of the second column), Maier's downhill leg makes an obvious move downhill, causing him to appear bowlegged, finally completely releasing the edge of the downhill ski, which he immediately steers downhill into the next turn (causing the tip divergence). That is the clearest image of the "phantom move" in this sequence. And it represents, by the definition above, the actual moment the left turn ends and the right turn begins.
HOWEVER--the "phantom move" does NOT occur only at the initiation. While it typically gets emphasized as a move to initiate a turn, it actually takes place throughout the turn. It refers to the notion that, while it is often the OUTSIDE ski that does the work--that bends under pressure and carves the turn, and that we balance on, and that must tip on edge and steer--it is more effective to focus our attention on tipping movements of the other, non-weighted ("phantom") ski. These movements initiate an often unconscious chain of movements that results in highly effective edging of the outside ski.
So in the first two frames of the sequence, Maier actively tips and steers his inside (left, uphill) ski. If he focused only on tipping the downhill ski, which bears most of his weight and does most (not all, here) of the carving, we would see a more-pronounced knock-kneed "a-frame," and his inside leg would interfere with the tipping of the outside leg. (And if he focused only on TURNING the outside ski, he would have to twist its tail out into a skid.) By the third frame, Maier has clearly started to reduce the edge angle of his skis, lead by the downhill foot and leg. The move that causes the obvious bowleggedness of frame 5, and presents the clearest image of the "phantom move"), actually BEGINS in frame 3.
To summarize, while Maier probably wasn't consciously thinking about ANY of these things, if WE want to try to duplicate his technique (at least as far as edging movements are concerned), we would focus on tipping the left ski left (toward its "little toe edge") in frames 1 and 2, then focus on tipping the right ski right (toward ITS little toe edge) in frames 3-8. That is "phantom edging" throughout the turn!
Please remember that "phantom move" is NOT a description of all the complex movements that take place, but of a simple THOUGHT that can trigger and sustain these movements! BOTH skis tip, and both skis turn, as a result of focusing on the inside ("phantom," if you must) ski.
In this great sequence, Hermann Maier clearly demonstrates the blend of both tipping and steering of the inside ski that I've referred to in the "perfect turn" thread. Whether you focus on the tipping or on the turning of that inside ski, both are involved. There is an inseparable biomechanical link between the two--tipping the lower leg (knee angulation) involves rotation of the femur. And you can't TURN the left tip left without first releasing its edge. So the very simple reminder to EITHER turn OR tip the inside ski into and through the turn can often be all it takes to make that "perfect turn."
Wow--lots of analysis to arrive where we started--the ultra simple advice to "turn the left tip left to go left, and the right tip right to go right." It works!
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雷达卡
发表于 2015-3-28 23:31:38
显身卡
发表于 2015-3-28 23:33:42
