Edited
>btw, you are interpreting the jump scoring correctly
Watching the recent Grand Prix performances, I see that the body does stay fairly well aligned with the foot. I don't think they take foot rotation relative to the torso to anything close to 90 degrees. It has to be much more subtle to look good.
As an example at a much lower athletic level, I can't imagine anyone appreciating a half-rotation jump (like a waltz jump) in which no torso rotation occurs in the air, but the rotation is simply obtained by hopping from foot-to-foot in 180 degree turn-out (spread eagle-like position, torso facing sideways). Just as many people don't appreciate Mohawks that depend entirely on 180 degree turn-out in place of on-ice rotation.
>Why do you say that too much stabilizing muscle could interfere with the angular momentum?
Basic physics. Stabilizing muscles, by definition, interfere with motion. For example, if you contract muscles next to the skin, they press down on the inner layers of body tissue, creating friction between them. That eliminates excess vibration, but the body's muscular-skeletal system isn't isolated enough to control vibration without slowing down desired motions, wasting energy and momentum.
It's called "moving with resistance".
And the extra friction also creates abrasion. The teacher of a Dance Kinesiology class I took at the University Of Maryland emphasized that "over-control" (what we are talking about) increases wear and tear on the body, and reduces range of motion (flexibility).
>Do you think that costumes can cause levels of vibration that could interfere with jumps?
If you had heavy rope tassels, they must absorb some momentum, but I've never worn that sort of thing and don't know whether it is important.
If I wear a heavy jacket, or a loose jacket, it adds a lot of angular momentum that slows down my spins. But I guess "real" figure skaters wear less, and this might not be so much of an issue.
Anyway, like a lot of things, it is a compromise:
Heavy boots store angular momentum, but also require more energy to lift and move.
A retired master said that Evan Lysacek said that he wanted heavy boots to store more angular momentum for jumps. Yet many skaters tell me they get less tired skating with much lighter boots.
In any event, the motions of the foot are better controlled than uncontrolled motions of the body and loose attachments.
I'm sure that long hair is involved in angular momentum transfer too - but it too can perhaps be controlled, and it adds a beautiful artistic effect. I love the way many ladies spin out their ponytails during fast spins.