8th in a multi-part series on skiing/snowboarding on hard snow.
Truth In Ice: Line Change 1 presented productive skidding as a means of generating friction and changing direction with ‘simple’ sequential movements.
To rapidly change direction without disrupting glide and grip, a rider needs command over the complexity of edge change, net pressure, and fore-aft pressure simultaneously. The amount of time and area consumed in changing direction at a given rate of travel is dependent on which body parts are involved in the sequence, how far each needs to move to do the job, how long it takes to move them, and the nature of COM displacement throughout the process. The faster the rate of travel, the greater the need for accuracy in all areas, so as not to over/undershoot each ‘movement target’.
That said, best to be mindful of what gets moved, and how.
If you have two objects of different mass moving at the same speed, it’s going to be easier to affect the path of the lighter object. The heavier object will have more momentum, and momentum tends to keep things moving as they are. The lighter object has less momentum, so ‘moving it’ will take less physical effort/energy, require less time, and the disruption created can be more accurate. In the context of alpine sport, the ‘objects of different mass’ are the torso/upper extremities, and base of support.
When a rider can alter their path by moving the lighter parts (lower legs, feet) the greater distance, and the heavier body parts (torso, COM) the lesser distance from one turn to the next, that rider can get more done in a smaller area in less time.
For the most part, a time-sensitive edge change will involve the base of support (feet on platform) moving relative to the COM, rather than the COM passing over the base of support. Rebound is used to propel the base of support from one arc to the next, rather than lifting the COM across the board from turn to turn. COM ‘crossing over’ works fine when there’s both ample time and a lot of unobstructed trail width available, but becomes problematic when the trails get narrow and time is short.
Truth In Ice: Net Pressure discussed flexion and extension of the legs as a means of controlling generalized pressure application in a turn. That same range of movement combined with accurate fore-aft pressure redistribution and time-effective edge change can be used to make a rapid transition of the platform from one turn to the next. Flexion-extension through the turn transition can thereby shorten the path taken by the COM. The shorter path takes less time, and consumes less area for each turn.
When a rider can use flexion-extension while also countersteering, they will see even more gains through economy of motion.
Most movement options discussed in this series are significantly affected by joint mobility. Joint mobility also plays a part in whether or not the dominant state of equilibrium is fluid or fixed. Fixed equilibrium often results when one or more limb segments are tasked with maintaining system stability, which means they are not available for the discretionary movements that characterize fluid equilibrium.
It’s possible to have full range of movement at one or more joints while stationary, but have very little once in motion. If you find that you can’t make the movement(s) you want to make, (or think you should make), when you want to make them, you are probably in a state of ‘fixed’ equilibrium.
Increased range of movement and combination of joint articulation can both complicate, and simplify riding on difficult surfaces. Initially, the greater range presents more opportunity to make mistakes and entrench ineffective movement patterns. With diligence, however, increased range can allow an athlete to channel rather than fight or resist the energy encountered in each turn, meanwhile fine tuning pressure and edge inputs so as to maintain harmonious contact between the platform and supportive surface. Harmonious interaction is going to be less conflicted, and therefore will require less physical effort.
With reduced baseline effort, there’s more physical and cerebral power available to rapidly change direction on a demanding surface without skidding.
It follows that riding difficult snow will become easier when the right things move in the right direction at the right time to the right extent. The hard part is taking the time needed to identify, filter and remove the excess.
In time, you may reach that particular level of technical refinement where the practice is not so much to make movements that assure grip, but to avoid making movements that disrupt grip.
In effect, “Accomplishing just about everything, by doing practically nothing”.