Well, for dynamic skidded short radius turns on steeps, we have talked about flexion-extension and fore-aft movements. Keep practicing both and increase the intensity of the movements as the terrain becomes more challenging. Additionally, experiment with your timing of these movements on different terrain. As the pitch increases, you will find that you need to initiate these movements a little earlier in your turn to account for lag time that exists between executing a movement and the board responding. This lag is not noticeable on typical resort terrain but can have a profound impact upon board performance on technical steeps.
The next concept to incorporate into your dynamic riding is "upper-lower body separation". In essence, this simply means allowing the lower body to rotate indendent of the upper body. The lower spine becomes the pivot point that allows the hips and legs to rotate under a stationary upper body.
Just as we can actively rotate our shoulders and upper body in either an anticipatory rotation to generate board pivot or a counter rotation to slow or stop board pivot, we can allow our board to generate lower body rotation while maintaining a stationary upper body. The edging movements and sidecut of the board generate these rotational forces.
So, as riders, why do we care about this? From day one, we have been told to keep our upper body aligned with our board right? Well, for 90% of resort freeriding, this remains true and is good riding habits. But, when we start riding steep terrain, moguls, steep trees, chutes, etc, we need quicker board response. In these riding environments, we want to align our shoulders with the slope or general direction of intended travel instead of aligned with the board.
The reason has a lot to do with lag time as mentioned earlier. The more mass to move, the slower it starts and stops; if you remain aligned with your board, you must start and stop your entire mass as you initiate and complete every turn. On technical steeps, this will create substantial lag time in every turn as you rotate your entire mass nearly 180 degrees every turn.
Now, if you position your shoulders inline with your direction of travel, you no longer have to start and stop your entire mass every turn. Allowing your lower spine to swivel freely, you can use twist and tilt to energetically turn your snowboard more effectively and efficiently without having to also turn your upper body along with it. Additionally, since the upper and lower body naturally want to realign, the snowboard will have a little extra rotational force upon it favoring a return to your general direction of travel down the will. In short, it initiate every turn quicker with better edge engagement and less skid. This is what is crucial on technical steeps to maintain control throuout the entire turn as well as maintain a desired speed.
So, to start practicing this, pick a nice blue run that is nice and straight. As you begin, pick an object that is straight down the run long distance; can be a tree, sign, lift tower, building, etc. Point your front arm at that object and keep it there. Place your back hand on your hip to help prevent "wagging the dog". As you ride, use your feet to twist and tilt your board through the turns allowing the sidecut to do the work. As the board turns, loosen up the lower spine to freely allow your hips and legs to move around with the board and rotate underneath your generally static, stable upper body. Some upper body rotation will still happen but your goal is eliminate all of it and keep your shoulders aligned with the slope. Every time your board is across the fall line, heelside or toeside, there will be an approximate 90 degree twist in the lower spine. Understand that at first, you may not have this range of motion and some upper body rotation may exist. With practice and stretching excercises such as Yoga, this is totally attainable.
Get the feeling of this technique which is also a huge part of doing correct "cross under turns". When ready, start incorporating this into your dynamic steeps riding and prepare to take your riding to the next level!