Skiing motor control can be defined as the registration, dominance, and regulation of the interactions between the skier, the environment, and the actions wished to be performed. It also can be explained as the process of initiating, directing, and graduating voluntary skiing movements.
When skiing, we need to coordinate and control our actions, and because of nature itself these actions are performed, we make use of distinctive capabilities as posture and balance control in motion, or visual and kinesthetic control through sensory information. In skiing movement control, sensory and motor systems constantly interact; changes in one system are manifested in the other. If we wish to improve our performance, we should keep a constant record of how we are sensing our body and the place it occupies in space.
Feedback and feedforward motor control
In feedback control (retroactive) we employ mainly vision and hearing as external information. In this type of control, actions are generally reactions; it is common to react to circumstances because of developing the ability to anticipate them. Usually, the skier responds after visual and auditory stimuli and this is a consequence of that stimulation, being a standard behavior at beginner levels.
Bernstein (1967) proposed that in feedback control, we apply a data comparison system between the information of what it ‘should be’ and what it ‘is’. This comparison serves us to regulate differences, correct inaccuracies, and guide our learning.
The feedforward control (proactive) uses proprioception and actions’ mental representation as internal information. Through mental representation, we simulate the actions that we will perform in relation to the environment, anticipate the motor response related to changes in it, and facilitate the analysis of sensory information that we will perceive during our motor execution. This type of control is applied in quick movements and in automated motor behaviors, minimizing reactive responses. Both types of control are complemented, each one in different circumstances.
We should also consider the following:
- Our performed adjustments about motor control not only depend on our body but also on the perceived external stimuli.
- Actions initial and final state are two essential references to our motor control.
- One of the causes of imprecision in skiing motor control is due, in large part, to the lack of development of feet sensory information.
Degrees of freedom
The organization of skiing movements and the coordinated control our body segments involved in the execution of those movements in three spatial dimensions is a complex problem due to the multiplicity of the degrees of freedom of these segments.
Movements used for skiing seem simple but, actually, have a complexity level presenting a motor control problem since the excess inhibits the efficiency of those movements. The degrees of freedom are used to describe the number of ways each body segment can move, which exceed those needed for skiing.
As the central nervous system controls at the same time different muscle states, Bernstein (1967) suggested the existence of motor control simplified mechanisms that reduce these degrees. Thus, for a beginner skier, there is muscle and joint initial rigidity (reduction of the degrees of segmental freedom) that will amplify while practicing, allowing more gestural fluency and overall flow in movements’ execution.
Coordination generates restrictions in the degrees of freedom. As each joint has its own degree of movement, we aim to dominate all joints, requiring a great sense of coordination since we should control four limbs that each one generates its own movement in multiple directions.
Restriction and progressive release of the degrees of freedom
The ability to control various movements’ variables is a remarkable feature, but during motor development, we face numerous segmental control problems and one solution is restricting certain degrees of freedom. This generally leads to body tensioning because of keeping joint angles that restrict movements’ freedom, as seen in beginner skiers.
After the initial rigidity process, it emerges a progressive relaxation of these degrees, assimilating a more dynamic and fluid motor performance. Movements’ amplitude of body segments rapidly develops over the course of the beginner’s first experiences, noting a progressive articular release as a result of practicing.
In short, the transition from beginner level to upper levels is characterized first by restricting and then by progressively releasing the many degrees of movement freedom, obtaining greater motor amplitude and fluidity.
Motor retention
When we learn a movement or an action on skis, the process of motor retention initiates which consolidates whenever practicing. This allows our body to ‘remember’ those movements and actions even after not practicing them for a period of time.
It starts on the basis of proper posture in which muscles are activated to contract and to relax so our body functions in a specific way. Continuous practice develops a motor memory, i.e., postural habits, movements, and actions made and evoked on the basis of previous motor experiences to be used at some point, even having spent considerable time since the last skiing practice.
This motor memory forms part of the long-term procedural memory, making remembering our capacity to return to skiing, and this is possible thanks to movements’ repetition that strengthen motor retention.
