What do you mean by mediated by the engine? In snowboarding the board really is an engine. You can define how much friction you give to the slope or your angle

What do you mean by mediated by the engine? In snowboarding the board really is an engine. You can define how much friction you give to the slope or your angle to it and therefore throttle. You also engage the board in a carve and get energy out of the carve in transition and this can be controlled by the length of the carve or how you shift your weight or engage your legs. Not to mention the route you decide to take on the mountain and the effect of that topology and snow conditions. This is true for skis as well.