I have put my foot in my mouth again haven't I? You see, I've never really thought about riding that way (indoor drills to learn turn finishing movements). And this question (turn finishes) messes my head up with respect to the last question (turn starts). Still, since turn finishes should really be the same thing as turn starts, I won't let myself weasel out of this that easily. However, we do need a caveat that the following drills are for regular snowboarding. Alpine riders on carving boards with high stance angles use different movements. Another caveat is that I'm making this up as I type. So expect this to be long winded, overly complicated and ripe for picking apart by the peanut gallery. There's a difference between a forum post and an article, ok?
Next, we need to understand that in the linked tip above, the drills are much simpler because in skiing there is no distinction between the movements required for left or right turns and there is little distinction between the movements required for different types of turns.
Snowboarding has two basic variables that make for distinctly different types of turns and therefore movements required to execute those turns: which direction (toe or heel) and whether the turn is a basic or dynamic turn (AASI terminology). So, instead of one movement pattern to cover, we've got four.
For a toe side turn, there are movements of weight from the toes/balls of the feet to the heels, the ankles go from closed to open, the back goes from rounded to arched and rotary movement of the foot/knees/hips/shoulders (if used) is to the big toe direction of the front foot. For heel side turns, these movements are "opposites". For both toe and heel basic turns, the legs generally start the turns rising from a bent (or flexed) position and finish the turns sinking back into the flexed position. It's possible to make turns using reversed leg flexing movements, but this is not relevant to the discussion at hand.
Dynamic turns are defined by having the center of mass travel a distinctly different path than the path of the board. It may be easier to think of this as extending the legs/boards out away from the body as one is riding. Most beginner riders use basic turns where the upper body stays within a few inches of being directly over the board. For the purpose of this discussion, I'm going to redefine the difference between basic and dynamic turns as basic turns using simultaneous foot/leg movement and dynamic turns using sequential foot/leg movement. Unlike basic turns, where both legs bend and straighten at the same time, in dynamic turns the front foot will pass underneath the body (front leg short) while the back foot is still extended away from the body (back leg long). As the front foot starts to extend away from the body (front leg long), the back leg passes underneath the body (back leg short). In basic turns, the body passes over the board. In dynamic turns, it's more of the board passing underneath the body. Another aspect of dynamic turns is board twist (different foot angles to the slope that causes the board to twist along its length). It's helpful to think of the board as being flat when underneath the body and on edge when its away from the body. At the point where the front foot is directly underneath the body, the front part of the board is flat where the back part of the board is still on edge from the old turn. This is the sequential movement of the feet from toe to heel. The front foot transitions first, then the back foot. Although it's possible to do basic turns using board twist, dynamic turns are rarely done without it. That's why, for the purpose of this discussion, I'm going to say basic=simultaneous, dynamic=sequential.
Now, let's look at three common inefficient movement patterns and some drills to introduce some more efficient movements: upper body rotary, stiff legs and back foot pivoting.
Many riders use a turning of the shoulders and hips as their first initiating movement. This is great for doing airborne 360s but not so good for turning on snow. At home, you can test this out with your socks on standing on the kitchen floor. Fling your arms around and see if it causes your feet to turn. If you do it hard enough, your feet will move a little bit at the end of the rotation. Now try tucking your chin to a shoulder (to "freeze" the shoulder movement) then turning only your feet. The movement is more immediate and greater. On snow, try riding holding your hands together in front of you. When you get comfortable, try riding holding your hand behind your back. If you feel the need to break the hold, you're not turning your feet enough.
Karate punches involve arm rotation in addition to the extension of the arm as a means to add power to the punch. We can use the same principle in reverse to add power to our foot steering. At home, sitting in a chair, extend one arm straight out away from your body and lift up your hand so that it is vertical (at a 90 degree angle to your arm). Now wave your hand by rotating it left and right. Think of this as pulling your hand with your thumb or pinky. Make a note of how far your hand turns. Do you feel the tension in your arm at the elbow? Now bend your elbow to bring your palm back close to your shoulder. From this position, rotate your hand while you simultaneously extend your arm out. You should feel less tension in the elbows and easily get more rotation of the hand. Try it a few times rotate your hand as you extend and retract your arm. We can do the same thing when riding by substituting our foot for our hand and our leg for our arm. We need to bend our legs more when we finish our turns and extend them more when we start our turns and we need to initiate rotation with our big and little toes. On snow, a drill to help develop these movements is to touch our hand to various body parts. I usually start with touching the hands to the top of the shoulders to start a turn and touching the knees to finish a turn. To increase the range of movement, try finishing the turn touching the shins at the top of the boots or touching your toes if you're really brave. That will really get you out of the stiff legged habit.
Riders who don't take lessons quickly discover the effectiveness of steering with the back foot. To start a turn, they rise up slightly, kick the foot around, then skid until the new edge engages. If these riders would learn how to twist the board, they could carve turns instead. A drill to
do at home is the dance move. Stand up. Lift both toes off the floor. Now transition the front from heel to toe. Get your balance, then move your back foot to toe side. Now repeat this moving going from toe to heel front foot first. Shorten the delay time, then change it so that you are simultaneously on toes on foot while on heel with the other. You'll notice that you have to rotate your hips to do this. On snow, the turning of the board can accomplish the same results, but knee or hip turning can help. The important part of this drill though is to get that thick head to understand that the feet can work independently going from toe to heel. The final step of this drill adds movement of the weight from centered to forward as the front foot transitions to toe or heel. The on snow version of this drill involves reversing the direction of the back foot kick out at the start of the turn. You actually kick the back foot down the hill at the end of the previous turn. If you do this and then set the edge without coming to a complete stop, you should get some "rebound" upunweighting. Use this to step hard on the front foot while simultaneously going to the new edge on the front foot only. After that, the back foot just goes for the ride around the new turn. This drill is great for introducing riders to the sequential movements used for dynamic turns.
So there you have it: a framework for introducing snowboarding movements and a rough cut at some drills for "finishing" snow board turns. Yeah I know video and graphics would be nice. But the day job is calling...