Bode vs. ydnar
Originally Posted by ydnar
I totally agree that the CoM has to be in front of the feet as far as our motion forward is concerned. But I am not constantly moving the CoM to be there. My skiing stance puts the CoM in front of my ankles and keeps it there. Even in the fore/aft plane I could argue that the only way to move the CoM forward and keep it there is by dorsiflexing the ankle. What I thought we were talking about was the process used to move the CoM from one side of the feet to the other (or allow the CoM to move from one side to the other) so that the force generated by my skis can be used to propel my body back and forth across the hill. It is this directing of the CoM that I am asking questions about.
My answer to your questions turns out to be a little complex. First I don't release a turn and engage a new turn. I release my CoM to move along a more balistic path which crosses the path that my skis are taking but if I am sking well the engagement of my skis with the snow never stops so my core is always activated. Even when I do become disengaged my core stays activated to provide the stablity that I need to prepare for and then actually re-engage with the snow. If anything when I am in the air preparing to land my core is working it hardest to provide the blocking I need to get my body into the position I want it in when I land. This is most true if I want to land the air in a turn. So, for me to release my CoM the core stays strong and the muscles of the outside leg relax. Those times when I am re-engaging it is again the muscles of the new outside leg that activate first or I will collapse, the core was strong when I left the ground (disengaged) stayed strong during the disengagement and was strong and ready to deal with the forces when I re-engaged the snow.
1. ydnar--wow, great post, and a wonderful explanation.
2. I think Bode Miller has a somewhat different approach to transition, which I'd like to explore here. Check out the final frame from Ron LeMaster's latest Miller montage:http://www.ronlemaster.com/images/la...c-2004-gs.html
What I see after blue gate clear at the bottom is that Bode is flexing his outside leg to release his CoM as ydnar describes, but he has also actually dropped his hips a little back (a characteristic Bode Miller move which is quite distinct from the other World Cup racers--you can watch the USSA DVD of 2003 winning World Cup runs with the sound off and immediately spot Bode Miller from how far back he is with the hips at the end of the turns.) As ydnar points out, he's letting inertia carry his CM to the outside. Unlike ydnar, by dropping the hips back and deeply flexing, he's also shortened, making his CM travel a shorter distance (the arc is shorter because he's closer to the feet) for a very fast transition.
I think this is one of the keys to Bode Miller's technique--in GS, SG, and DH he typically generates higher edge angles than his competitors (and--especially in the speed events--can therefore ski and carve a tighter line) while still managing a very fast transition to be able to displace the skis and CM to the opposite side for the next turn. Bode Miller's technique imposes greater dynamic balance demands (where Bode Miller is exceptionally skilled, even among top World Cup racers) and the fore-and-aft balance demands become riskier on today's short slalom skis (where Bode Miller has run into trouble this year.)
As a result, Bode Miller says "I like to feel like I'm changing edges with my knees". (Which, I believe, is how it would feel if you were in this position with the hips back and knees flexed.) (Quote in Ron LeMaster's online slide show "Alpine Racing Technique".)
This (if it actually can be replicated by other skiers with less extraordinary dynamic balance skills--you don't see it in the other World Cup racers today) may be the technique of the future on the World Cup. After Miller's GS win at Soelden to kick off this year, one of the Austrians (Karl Schranz?) sniffed "if he keeps winning, soon all the young Austrians will be skiing like a snowboarder." (Which I took to mean (A) with the inside hand skimming the snow, and (B) with this hips back position at the end of the turn, reminiscent of a snowboarder in a carved turn.)