Nairn Brian C, Chisholm Stewart R, Drake Janessa D M
School of Kinesiology & Health Science, Faculty of Health, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3.
Man Ther. 2013 Dec;18(6):498-505. doi: 10.1016/j.math.2013.03.003. Epub 2013 Apr 28.
Slumped sitting is a commonly used reference posture when comparing effects of upright sitting in both clinical and non-clinical populations alike. The exact nature of slumped sitting has not been clearly defined, including regional differences within the posture, and how the passive nature of slumped sitting compares to an active-flexion posture. Kinematic and electromyographical (EMG) data were collected from 12 males during three repeats of slumped sitting and seated maximum forward flexion. Spine angles were defined in four regions (three thoracic and lumbar) as well as for the pelvis, and EMG was collected from eight muscles bilaterally. Kinematic data were expressed as a range of motion (in degrees), and as a percent of full forward flexion while seated (%SIT-FF) and standing (%STAND-FF). EMG data were normalized to a percent maximum contraction (%MVC). Results showed that slumped sitting is characterized by 10° posterior pelvis rotation, near end-range flexion of the mid- (90%SIT-FF) and lower- (81%SIT-FF) thoracic regions, and mid-range flexion of the upper-thoracic (51%SIT-FF) and lumbar (43%SIT-FF) regions. Comparison of slumped by %STAND-FF showed the upper- and mid-thoracic regions to have high variability and large values (over 100%STAND-FF). Muscle activation showed a significant 3%MVC reduction in the lower-thoracic erector spinae muscle when moving from upright to slumped sitting. These data highlight the postural differences occurring within different spine regions, and interpretations that could be drawn, depending on which normalization (sit or stand) method is used.
在临床和非临床人群中，当比较直立坐姿的效果时， slumped sitting（瘫坐）是常用的参照姿势。瘫坐的确切性质尚未明确界定，包括该姿势下的区域差异，以及瘫坐的被动性质与主动前屈姿势的比较。在12名男性进行三次瘫坐和坐姿最大前屈重复动作期间，收集了运动学和肌电图（EMG）数据。脊柱角度在四个区域（三个胸椎和腰椎区域）以及骨盆处进行定义，并且双侧从八块肌肉收集EMG数据。运动学数据以运动范围（度数）表示，并以坐姿（%SIT-FF）和站立时（%STAND-FF）完全前屈的百分比表示。EMG数据归一化为最大收缩百分比（%MVC）。结果表明，瘫坐的特征是骨盆后倾10°，中胸段（90%SIT-FF）和下胸段（81%SIT-FF）接近终末范围的屈曲，以及上胸段（51%SIT-FF）和腰椎段（43%SIT-FF）的中间范围屈曲。通过%STAND-FF对瘫坐进行比较显示，上胸段和中胸段具有高变异性和较大值（超过100%STAND-FF）。当从直立坐姿转变为瘫坐时，下胸段竖脊肌的肌肉激活显示出显著降低3%MVC。这些数据突出了不同脊柱区域内发生的姿势差异，以及根据所使用的归一化（坐姿或站姿）方法可能得出的解释。
