Application d'une approche transversale de l'appareil locomoteur au confort siège

The risks to be wounded when wearing heavy load are well-known. On the opposite, the sitting position, assimilated with the concept of rest and comfort, may appear riskless. However, the sitting position may generate musculoskeletal disorders. Recent studies in biomechanics make it possible to better understand the parameters of discomfort related to the sitting position. The articulations of the human body must respect physiological positions, allowing a muscular economic posture. The musculoskeletal disorders originate from an imbalance of the muscular tone. The muscular contractions, which are repeated or constant, even with a low amplitude, are harmful. This results into pain due to the spasms of the muscle. If the spinal curves are too much or too less accentuated in sitting position, or if the articulations of the body are in a position far from their neutral position, important stresses and strains are exerted on articular tissues. These strains will generate articular information responsible for the abnormal modification of tonicity. However, a posture, even if ideal, cannot be maintained during a too much time. This one will have noxious effects on the metabolism of articular tissues and on muscular fatigue. A relative mobility between certain parts of the seat may decrease these effects by supporting an alternation of strains on articular tissues. It is necessary to address the problems of seats' comfort by taking into account the morphological diversity of the users and while considering the biomechanical and mecanobiologic constraints.