Originally Posted by chad
Ken, by hips do mean ilia/pelvis? While the movement above the ball joint is subtle, it is critical to allow for 1. to be possible. I think leaving it at "all sorts" is mean :), how about some reasons? Regarding 4., the head holds major receptors, it is the foundation for our sensation and proprioception, whether we want to or not, it is all about performance, all the time.
What is the benefit to lengthening the spine as it pertains to the use of the hip joints?
It feels to me that the major difference in slalom/GS turns is how the spine/trunk separates, one being more active/concentric the other more controlled/eccentric due to the differences in force management required. The separation is very similar though.
The part with the red highlights is what I'm calling hips. Forget all the other stuff in the image. I just snagged something from Mr. Google. Also, I said it is an intent to keep them facing down the hill and not that they don't move. They do and it is to accommodate all the other movement.
The legs turn in the hip socket (1)
The hips mostly face down the fall line (2)
I'm not saying they are locked to the fall line. But in general terms you want them facing down the fall line as much as possible. They will go side to side but I think this should be based on your anatomy, turn shape and how much ROM your femurs have. The intensity of the turn will come into play to. Through the turn, they have to move to accommodate for things like your inside leg at least fairly close in length to your outside leg. Watch someone do pivot slips properly and you'll see them point straight down hill at transition, and as far downhill as they can during the rest of the turn. Same thing on a short radius carved turn. There is more angle to them but that is to accommodate for you legs and upper body.
The upper body (above the hips to shoulders) moves as required above the hips for all sorts of reasons but these should be subtle (3)
I wasn't trying to be mean but I was trying to be on time for work. That didn't happen either . Above the hip movement I'm talking about is primarily the spine. It twists, bends, extends and flexes. Some of the reasons are the arms are moving, you need to stay in balance, you need to make sure you positioning your CoM appropriately for the turn at hand, you need to keep pressure on your skis, you have to accommodate for terrain, to name
Head moves as required but for tactics and not performance (4)
What you described is what I meant. It tells the rest of the body what to do for performance but the head doesn't edge, pressure or rotate the ski; it tells something else to do that. You could argue that it contributes to balance, but as long as it is connected in the normal fashion, and you aren't depriving any of your senses of input (i.e. look up so you can't see terrain or it makes you dizzy). the head doesn't contribute much. It's kind of fixed and usually just turns side to side to receive the data it needs.