So in reviving this thread I hope to delve more into the subject of the actual role of the upper body during a ski turn, how we accomplish those objectives (movements used), and the role of functional tension in creating the stable anchor so often mentioned in our advice.
So what is the role of the upper body? Is it to actively move about? Are those movements purposeful and disciplined, or simply a consequence of being passively carried about like SharpEdges once described as "a sack of potatoes"?
Said simply a stable and disciplined upper body facilitates better balance and flow. Mostly because that eliminates the need for a lot of the balance corrections we would have to use if we allowed it to just be tossed around. Another saying I've seen used is "Stay in balance and you spend less time seeking balance". But what do those saying actually mean when it comes to how we move the torso and arms?
I use the catch phrase 3D Skiing. It means use Disciplined, Deliberate, and Directionally relevent actions. Here's a brief definition of those terms as related to that 3D Skiing conceptual model.
Disciplined: Know how and how much you need to move the entire upper half. Additionally eliminate extraneous and unintended movements that may occur.
Deliberate: Know why you are moving those body parts in the first place and what you expect to accomplish with those movements.
Directionally relevent: Constantly and consistently move towards the future, decide where that is and keep your entire body moving there. When you do that the need for big jerky correction movements is almost completely eliminated. So are movements away from where you want to go. For example, leaning into the hill moves the torso back uphill and the inside hand drops back towards the tails. An uphill step /stem move the foot uphill and away from the new turn.
So what about functional tension? What is it's role? It helps us maintain a more balanced stance since the small pertubations we encounter don't toss us around as much and in turn that means we don't have to make as many balance correction moves. Of course too much tension can have the opposite effect, so excessive tension must be avoided. Static, rigid stances are the most common outcomes we see when excessive tension is present. But what is an appropriate level of tension in the upper body and how can we teach it? It's actually pretty easy. What follows is a sample progression I've used for years.
Use a two person format and have them face each other. Have one person press on their partner's shoulder like they are trying to shove that shoulder about a foot backward. Remember to express to them to press but not punch their partner's shoulder. The second person allows their partner to move the shoulder with no resistance. That established the amount of functional tension needed to keep the upper body passively involved in balancing activities. Once they can do this consistently, have the second person resist and not allow their shoulder to be moved backwards by their partner. The person doing the pressing will notice that and they will almost automatically begin pressing harder. That small amount of additional pressing isn't a bad thing. Just don't let this activity turn into a test of wills and a shoving contest. What we're trying to establish is an awareness of the level of tension it will take to produce and maintain a stable and disciplined upper half of the body. In most circumstances the feedback I get is, "REALLY? You actually want me to ski with that much core and upper body tension?" Which tells me they are in the middle of an epiphany about how little they currently use their upper body to facilitate and maintain good balance. Or it tells me how far out of balance they are when they ski because that out of balance stance requires a lot more muscle tension. Obviously getting them more centered eliminates this problem.
One final note here is that I always anticipate a short excessively rigid phase where they also carry this higher level of tension in their legs, so I don't choose steep or bumpy terrain to begin skiing with this much core and upper body tension. Eventually, this excessive tension in the legs and hips disappears as they learn how to keep them less tense while maintaining the right amount of tension in the core and upper half. If not we work on medium speed traverses in bumpy terrain.
How this relates to the OP and how we integrate upper and lower body movement? Knowing The DIRT establishes how we can get into a well balanced stance. The next level is to understand how functional tension affects our ability to maintain that well centered stance.