Phasing of flexion/extension
Originally Posted by BigE
Watched the clips again. Have to say this:
Check out "The skiers edge". Especially the part which deals with the different phasing of flexion and extension. The ESA videos show the extension through neutral, and flexion through the turn. The HH video shows extension in the turn, and flexion through neutral..
This is an interesting subject. The pattern that you saw in HH's skiing is the general pattern that is accepted for PMTS. Within a PMTS framework, these are the reasons. Two of the most important requirements in each turn are that the skis roll through flat during the transition and that during the engagement phase of the new turn that the inversion of the new free foot lead the movemengts of the new stance foot and the rest of the body.
In PMTS, the movement of flexing the old stance leg is the single most effective and efficient movement that releases engagement of the edges and flattens the stance ski to the slope. It does this very effectively and without other negative effects. Students working to do an effective release live by the mantra "flex, flatten." This alone starts the skis seeking the fall line and this result can be enhanced by puling the free foot back. without any steering, one can go from traverse to fallline with a completely flat ski in a very, very short distance.
After inversion of the free foot, increasing flexion of the new inside/free foot works to free up greater outward rotation of the femur and therefore increase the effects of free foot tipping.
So, flex the old stance leg some to release, continue to flex the same leg more as the turn progresses to increase engagement.
However, the other side of the coin is stance leg lengthening. The stance leg must lengthen during the engagement phase for several reasons. First, stance leg flexion flattens the stance ski. If the stance leg is flexed at the same time as the free leg in an attemp to increase engagement, then the actions of each leg are creating opposite effects: the free leg is flexing to allow greater engagement and the stance leg is flexing to decrease engagement. So, the free foot is flexed while the stance leg is allowed
Lengthening the stance leg also assures that there is a long leg to flex during the next release. If both legs flex during the engagement phase, then where is the new flexion for release going to come from.
Besides these issues related to phasing release/engagement with independent flexion/extension, lengthening the stance leg during engagement and flexing during release has a number of other benefits. It allows the pressure of the turn to be taken on structural rather than muscular support. It works with counter balancing and counter acting movements to decrease steering and rotational input during engagement (steering has a ski flattening and break away effect). It provides greater sensetivity to free foot dorsiflexion for fore and aft balance adjustments. Etc.
Now If you wish to flatten the stance ski to drift a turn then of course flex of the stance ski during engagement is what you want, but in general, the opposite wil be preferred.
For PMTS extension at release starts a whole series of events in which the skier changes edges without a release (they go BTE to other BTE). The up down, the lack connection during the top of the turn, the need for upper body rotation an/or steering, etc. . . . all become a cyclical self reinforcing process. For PMTS the phasing is clearly consistent with PMTS the other is not.
The main developmental issue related to this within PMTS is whether the flexion that does happen at the effective time is an active lightgening/raising of the leg or whether it is a relaxation move that more actively moves the CM deeper into the turn.
The Skiers edge issue is interesting and I think has undergone some changes/development on the PMTS side. Originally many PMTS people thought that the skiers edge movements worked well for PMTS especially powder skiing). Harald had said so in one of his books. Then there was a disticntion that was made to tghink of the extension phase as beeing the apex of the turn. That makes the Skiers edge movements more consistyent with PMTS notions. However there is another issue. That is that the skiers edge tends to teach people to push on the stance leg during extension in order to move the CM into the turn. In PMTS, the leg lengthens BECAUSE the CM moves into the turn not the other way around. So that more recently, none of the PMTS coaches that I know endorse use of the skiers edge without question. Most don't think it reinforces the most effective/efficient movements and Harald has outright said he doesn't endorse it's use.
Originally Posted by BigE
In all fairness, what I believe is being compared is the pinnacle of PMTS vs. an acceptable point somewhere in the development stream the PSIA teaching. (Which is why I asked for real high level demo turn videos.).
Probably. For me this is not the issue though. Even if provide someone just doing the Green PMTS skiing test -- which would supposedly be a much lower general skiing level -- all of the movements that I would pick out as being worthy of contrast between the two systems would still be there. I'll think of doijng this. However, then people would complain that I'm saying that the Green test skier is "better" than the ESA examples and we are back in the same useless set of issues. I found the above post of yours to be a useful connection of the videos to issues that a skier can care about. Thanks BigE.