Posture and movement
There is an interdependent relationship between posture and movement. Movement is the development of various postures interconnected, starting and ending in a specific posture. Movement could be considered as dynamic and progressive postures’ flow, and posture as a potential movement. Movement is influenced by posture and posture influenced by movement. An appropriate skiing posture allows appropriate skiing movements and vice versa.
All movements are associated with two postures: an initial and a final one. Posture changing is accomplished with movement, i.e., our posture is the necessary basis for our movement execution. Movement performance generates posture disturbance because it modifies our body’s center of gravity. Most of the time the brain is not concerned with moving the body but keeping it stable (Carpenter & Reddi, 2002).
Some studies point out the dissociation between movement control and posture control and its authors propose that posture is remembered better than movement, suggesting that posture is represented at a higher hierarchical level, as well as neurons encode body postures,and some insinuate the possibility that our brain activates neurons for posture and neurons for movement.
The mental representation of movement and posture
Movements’ goal is to carry one or more body parts to the desired posture, so these final postures should be mentally represented before visualizing the movements to perform. If we have the image of the final posture before executing a movement, we can self-correct if the course of that movement does not lead to the visualized posture. Therefore, it is essential that our mental representation of the final posture exists before the first movement is carried out. In conclusion, the skiing stances we want to adopt should be represented independently and before the movements’ execution.
Posture and vision
Our vision is an important source of information for posture control, allowing body orientation in relation to gravity and to the horizon. The importance of visual information in postural control increases with our technical level. The motion of the visual environment is detected through sliding images on the retina and this detection allows us to control our postural oscillation.
Postural control through gaze
Looking at a specific point increases our postural stability and helps a better assessment of our body oscillations by diminishing them. Our posture is influenced by horizontal and by vertical lines of the visual field. Simenov et al. (2009) demonstrated that looking at a vertical reference while being on an inclined surface increases postural stability, and that posture is more stable if this reference is located closer.
A reduction in visual acuity or insufficient contrast sensitivity, being our own or generated by environmental conditions, decrease postural stability. The visual system dependence in balance control is greater in an inclined posture than in an upright posture (Riley et al., 1997).
Reaction to horizontal viewing loss
When positioning our body laterally to the inclination of the slope, gaze horizontality is modified. Through the righting reflex, we try to recover the horizontal visual reference straightening our head over our trunk, and our trunk over our feet, but sometimes we tend to over incline our body uphill, losing support on the downhill ski.
Posture and balance
Posture and balance are the basis of our skiing motor activity, as well as the foundation in which our learning processes are settled. We achieve proper balance when assuming posture control through body positioning, concurrently with positive mental and emotional attitudes.
Posture control and balance control are often confused. Although both are interdependent, balance control is the ability to keep our center of gravity over our base of support, and postural control is dominating our body’s segments alignment, which includes orientation and stability, necessary requirements for movement performance. The way in which we maintain balance is by the necessary postural alignment and adjustments due to suffering perturbations when moving on snow.
Body differences exist between skiers. Our base of support is not the same, as well as our walking. Some people walk with their feet rotated outward while others inward, some tend to supinate rather than pronate their feet or vice versa. This affects our skiing stance and it also affects our balance. According to Mesure & Cremieux, any active or passive posture change activates mechanisms to preserve balance in the chosen stance.
Balance disturbances affect our posture control. The inevitable tensions of balance control lead to a natural structured posture. In addition, it should be considered that traumatic experiences in which accidents and injuries leave, force some skiers to protect their body posture. This defensive or protective posture consumes energy and weakens balance because the skier is striving while trying to achieve a tolerable stance.
Controlling our posture is controlling our balance. Postural fixations are ways of keeping balance. Exerting a particular stance is keeping our body segments in proper relationships among themselves so our center of gravity falls within the base of support.
Interdependence between posture and balance
If our posture is defective, we will consume energy by struggling against imbalances and potential falls. An efficient posture allows for effective balance maintenance. Our skiing stance is based on muscle tone and bone alignment, and balance relies on proprioceptive, vestibular, and visual systems. Posture is linked to our body and balance is linked to space. Posture is built from our feet and balance from our head. Balance is an action and posture is the movement to get that action.
Skiing balance depends on the postural control we can obtain and for this, the key is an appropriate posture to the current situation. If we pretend to balance by keeping a rigid posture, we will lose mobility and sensitivity. Balance is achieved by a proper posture, not by muscle force but by aligning body segments in relation to skis, terrain inclination and external forces.
Factors affecting posture
Each skier’s posture has its own characteristics and varies according to his morphology, technical, physical and motivational conditions. Generally, it is considered as internal factors those that come from the same skier to adjust or modify his posture. It is noted two types: hereditary or physiological factors such as body morphology in terms of height, weight, the center of gravity, muscle tone, flexibility, coordination, kinesthetic consciousness, and psychological factors as thoughts, feelings, preferences, attitudes, and mood states.
Our psychological state affects our skiing posture. Proper posture provides confidence to us and reduces the perception of our limitations. If we are experiencing a stressful situation, our posture will be characterized by excessive legs rigidity. When the psychological pressure becomes unbearable, then we quit stiffness and our legs give up provoking the fall. We keep this rigid stance because of fear to let go and to fall, blocking knees and pelvis. Our attitude in this situation is inflexible, revealing insecurity and the need to hold on to a rigid support. This condition of hips and knees locked counteracts grounding (tension download), rendering the proper connection between our feet and snow unattainable.
Posture also influences the way of our thinking, since poor posture creates negative thoughts that lead to poor self-evaluation. The function of our posture also affects our skiing attitude. If we have a pro-active attitude, we treat ourselves positively and with confidence, expressing it in our postures. On the other hand, a collapsed posture promotes the generation of negative memories and thoughts leading to a reactive attitude towards skiing. Emotions and thoughts affect posture and the level of energy as these affect emotions and thoughts (Peper & Lin, 2012).
The external factors that affect our skiing posture come from the environment (gravity, support surfaces, forces generated by motion, relation with the inclined plane) or gear factors like frontward tilt and boot stiffness.
