“White day”: it was under these unattractive weather conditions that I started my ski season. The tracks were covered with a thick fog restarting the visibility a few meters, which made any distinction of the snowy relief impossible. Only a piquet by the track was visible as the descent progresses. No contrast between snow and sky. The orientation task was complex: difficult to orient yourself, estimate your speed and adopt the right tilt on the ground.
In such conditions, balanced losses have proven to be frequent. For my descent companions, they have evolved into a nausea. In my case, symptoms of fatigue and dizziness persisted several hours after this outing. We have all been victims of “skiing”, a physiological reaction that is similar to transport evil. What is it due to?
A variant of transport evil
Above all, it should be noted that the ski disease should not be confused with the “acute mountain pain”, which occurs independently of the weather and only in very high altitude (due to the low oxygen content of the air).
Ski evil is a variant of “cinetosis”, a learned word designating both seasick and transport evil. It is characterized by symptoms such as vertigo, drowsiness or pale (so -called “neurovegetative” symptoms), which can worsen in nausea and vomiting in the most severe cases.
Sensitivity to cinetosis, and therefore to skiing, as well as the reactions that characterize it can differ strongly depending on individuals.
If most of us have already paid the film price during travel, the bodily mechanisms that are originally not fully understood.
The causes of skiing
The scientific community mainly agrees on two theories to explain the problems of cinetosis.
According to the first, the cinetosis would result from a “neuronal inadequacy”. To perceive movement, the central nervous system integrates and continuously processes sensory information transmitted by the eyes, the inner ear and the contraction of certain tissues. Thanks to this data, and based on similar movement experiences kept in memory, the brain can estimate the position, orientation and movement of the body.
However, if the sensory information is poor or corresponds to a situation rarely encountered, the estimate of the movement by the brain can be inconsistent in relation to the forces actually suffered. The brain interprets this dichotomy as a conflict and attempts to improve its understanding of the forces undergone by the body. If the conflict persists, it can trigger the appearance and development of symptoms.
Cinetosis will eventually disappear once the brain has resolved the conflict, which explains why the symptoms eventually dissipate.
The second theory suggests that the cinetosis occurs in reaction to a repeated “postural instability”. By losing the balance, we carry out rapid movements by reflex – for example bringing the leg by stumbling to the ground – to find our stability. In a situation like a sea trip or a ski descent, these balance losses can occur frequently. If they are repeated, the brain considers that the different strategies used to stabilize the posture are ineffective, which then leads to the appearance of symptoms.
Although few scientific studies have looked into ski evil, these two theories constitute explanations relevant to this phenomenon. An insufficient perception of movement seems to be the main cause, which would result in difficulties in orienting itself and finding its balance.
Due to an insufficient perception, switch to skiing on a relief or in a spilled that the brain has not properly anticipated translates both in a conflict between the estimated and real forces on the body, and by an imbalance ski position.
SKIER on fields of bumps and irregular slopes is particularly conducive to this kind of experience, especially if the visual field is restricted as in the event of fog. Skiers with visual disorders such as myopia, hyperopia or astigmatism also seem more sensitive to skiing.
In addition, having your feet and ankles immobilized by ski shoes also restricts somatosensory capacities (the perception of body movements). The perception of movement by the inner ear can be altered by repeated atmospheric pressure changes following the succession of climbs and descents.
What are the aggravating factors of skiing?
Not all individuals are equal in the face of the symptoms of cinetosis. It is likely that a person vulnerable to seasickness or car sickness will be sensitive to skiing. This is also the case for people sensitive to migraines, dizziness, or who have disorders of the inner ear.
External factors can also worsen this sensation. This is for example the case of the visibility conditions of the track (relief, slope, obstacles). These play an important role, allowing the skier to orient himself and adapt his body position in order to find his balance. In addition, at high altitude, the lack of oxygen can also promote sensory perception anomalies, which can result in an attenuated sensory perception, an alteration of the perception of spaces, or poor visual assimilation of objects.
The ski style can also have an impact. Sliding situations without apparent movement of the body can be interpreted as paradoxical by the brain. Slaloms with skiing can also accentuate this effect: these movements are repeated every 0.5 to 5 seconds, which corresponds to a frequency range of 0.2 to 2 Hz, beach on which the brain is struggling to distinguish translation and rotation of the body according to the signals of the inner ear. He can then interpret these movements as an effect of Coriolis, in other words the feeling of turning on oneself when this is not the case. This effect occurs for example when you make rotations of the head while being subjected to another rotation, which can correspond to turning your head quickly while you take ski turns. In this situation, the brain cannot properly interpret the direction of rotation of the body.
The psychological dimension is also crucial in the case of cinetosis. In people little comfortable on skis, stressed, fearing to fall, or being afraid of the void, skiing can be accentuated. In such a context, it is important to keep self -confidence, to remain optimistic and to be aware that such conditions can be conducive to skiing.
Finally, according to certain hypotheses, alcohol consumption or smoking on the slopes could accentuate the skiing, because the dilation of the resulting blood vessels would disrupt the functioning of the inner ear.
What treatments?
Certain cinetosis remedies are acclaimed on the basis of a positive individual experience. However, in fact, there is no universal palliative. Everyone reacts and heals differently, according to their own receptivity. If for most people, it is possible to get used to it by dint of experience, a minority of people is not able to get used to these situations and must use effects attenuators.
It is possible to fight skiing by improving the faculties of movement perception (“sensory picking” in English). At the visual level, optical corrections to myopia, hyperopia, or astigmatism disorders, can be used. Some ski mask masks screens also make it possible to better distinguish the relief in the fog.
Regarding the perception of body movements (somatosensorial), techniques such as acupressure – for example bracelets pressing the hollow of the wrist, used for other forms of cinetosis – can act by improving proprioception. For vestibular perception, few techniques exist, although stimulation by bone conduction on the inner ear can slow the development of transport evil.
Some people use drug treatments to limit the cinetosis. Vestibulosuppressants, as scopolamine are sometimes used to limit dizziness or vestibular migraines. Finally, taking antihistamines, such as dimenhydrate or cinnarizine, makes it possible to limit nausea symptoms, but can be accompanied by side effects such as drowsiness or troubled vision.
