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Effet de la variation des paramètres ergonomiques du siège d'avion sur les phénomènes biomécaniques et les actions musculaires associés au transfert assis-debout

Abstract : Sit-to-stand transfer (STS) is a task executed multiple times a day. It is a prerequisite for walking and is fundamental for independence. This task requires fine coordination between the linked body segments and a precise muscular pattern. Although it has been studied by different means (dynamics, kinematics, EMG), there is still a lack of standardization regarding its determinants. STS transfer can be separated into two main phases, a postural phase where trunk flexion occurs and a focal phase when lower limb extension takes place. STS is affected by seat parameters, some of which (e. g. height and armrests) have been studied, but most of them have to our knowledge not been given attention. In particular, ergonomic parameters related to sitting seem to enter into duality with STS. The aim of this thesis was to evaluate the influence of backrest reclination, covering foam density and the presence of a row of seats at the front on STS biomechanical (ground reaction forces) and electromyographic parameters. Reclining the backrest led to modifications in the muscular activity in the postural phase, mainly trunk muscles, with limited effect on the focal phase. Higher cushion foam density shortened the postural phase duration and modified the activity levels of the upper trunk muscles and knee extensor during this phase. It also allowed for a higher vertical velocity peak in the focal phase. Adding a row of seats which limited the free space at the front caused a modification of the STS strategy, with lower leg muscles and thoracic extensors more active in the postural phase, suggesting a more controlled movement, and anterior muscles of the lower limbs more active in the focal phase. This costly strategy allowed for a higher vertical velocity at seat-off, to compensate for the weaker forward velocity reached. Those results highlight the adaptations to various constraints of the postural phase parameters for a successful STS transfer. The ergonomic parameters studied are mostly associated with known static considerations while maintaining a sitting posture. Thus, optimal characteristics considering the dynamic aspect of STS as well and allowing for a balance between those 2 aspects can be deducted. This work sheds a new light on STS control and has direct implications for seat design, in particular for air travel.
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Submitted on : Tuesday, October 26, 2021 - 3:27:10 PM
Last modification on : Wednesday, November 3, 2021 - 10:02:00 AM

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2018TOU30374a.pdf
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  • HAL Id : tel-03404272, version 1

Citation

Nadège Tebbache. Effet de la variation des paramètres ergonomiques du siège d'avion sur les phénomènes biomécaniques et les actions musculaires associés au transfert assis-debout. Génie mécanique [physics.class-ph]. Université Paul Sabatier - Toulouse III, 2018. Français. ⟨NNT : 2018TOU30374⟩. ⟨tel-03404272⟩

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