Makhsous Mohsen, Lin Fang, Hendrix Ronald W, Hepler Matthew, Zhang Li-Qun
Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois 60611, USA.
Spine (Phila Pa 1976). 2003 Jun 1;28(11):1113-21; discussion 1121-2. doi: 10.1097/01.BRS.0000068243.63203.A8.
The seat and back contact force, pressure distribution, lumbar lordosis, and low back muscle activities associated with a new seat design with adjustable ischial support and backrest were investigated using kinematic, kinetic, electromyographic, and radiographic measurements.
To investigate the biomechanical effects of adjusting ischial and backrest supports during sitting.
Sitting may induce posterior rotation of the pelvis, reduction of lumbar lordosis, and increases in muscle tension, disc pressure, and pressure on the ischium and coccyx, which may be associated with low back pain. A device that reduces the ischial load and maintains lumbar lordosis may help increase seating comfort and reduce low back pain.
Fifteen office workers with no known low back pain history were tested. Contact pressure distributions, reaction forces between the buttock-thighs and seat and between the back and backrest, load carried by the seat pan and backrest, sacral inclination, lumbar lordosis, intervertebral space of lumbar spine, and muscular activity in stabilizing the trunk were measured for sitting with and without ischial support and with adjustable back support.
When the ischial support was relieved, the center of the force on the seat and on the legs of the chair, and the peak center of pressure on the seat, were significantly (P < 0.002) shifted forward toward the thighs. The total contact area on the seat pan and on the backrest was significantly decreased and increased, respectively (P < 0.001). The sacral inclination, total and segmental lumbar lordosis, and lumbar spine disc height were significantly increased for sitting upright with backrest, with the lumbar curve close to that during standing.
Sitting with reduced ischial support and fitted backrest to the lower spine altered the contact area, reduced peak pressure under the ischia, reduced muscular activity, maintained total and segmental lumbar lordosis, rotated the sacrum forward, and increased lumbar intervertebral disc heights, which could potentially reduce low back pain.
采用运动学、动力学、肌电图和影像学测量方法,对一种具有可调节坐骨支撑和靠背的新型座椅设计相关的座椅与背部接触力、压力分布、腰椎前凸以及下背部肌肉活动进行了研究。
研究坐姿时调节坐骨和靠背支撑的生物力学效应。
坐姿可能会导致骨盆后倾、腰椎前凸减小,以及肌肉张力、椎间盘压力、坐骨和尾骨压力增加,这些可能与下背痛有关。一种能减轻坐骨负荷并维持腰椎前凸的装置可能有助于提高坐姿舒适度并减轻下背痛。
对十五名无已知下背痛病史的办公室工作人员进行测试。测量了有无坐骨支撑以及靠背可调节时坐姿的接触压力分布、臀部 - 大腿与座椅之间以及背部与靠背之间的反作用力、座板和靠背上的负荷、骶骨倾斜度、腰椎前凸、腰椎间隙以及稳定躯干时的肌肉活动。
当坐骨支撑减轻时,座椅和椅腿上的力中心以及座椅上的压力峰值中心显著(P < 0.002)向前向大腿方向移动。座板和靠背上的总接触面积分别显著减小和增加(P < 0.001)。使用靠背直立坐姿时,骶骨倾斜度、腰椎总前凸和节段性前凸以及腰椎间盘高度显著增加,腰椎曲线接近站立时的曲线。
采用减少坐骨支撑并使靠背贴合下脊柱的坐姿可改变接触面积,降低坐骨下方的峰值压力,减少肌肉活动,维持腰椎总前凸和节段性前凸,使骶骨向前旋转,并增加腰椎间盘高度,这有可能减轻下背痛。