Biomechanics Research Laboratory, Department of Kinesiology, PED 107, 3560 Watt Way, University Park Campus, University of Southern California, Los Angeles, CA 90089, United States.
Hum Mov Sci. 2012 Apr;31(2):397-407. doi: 10.1016/j.humov.2011.05.006. Epub 2011 Jul 22.
Repetitive loading of the upper extremity musculature during activities like wheelchair propulsion can lead to fatigue of surrounding musculature causing irregular segment kinematics. The goal of this study was to determine the effect of increase in load on the kinematics of the scapula in users with paraplegia and tetraplegia. Data were collected on 18 participants (11 with paraplegia and 7 with tetraplegia) using an electromagnetic motion tracking system (100Hz) and force sensing pushrim (200Hz). The participants propelled under no load and loaded conditions at their customary propulsion velocity. On average a 60N increase in force was elicited with the experimental protocol. Users with tetraplegia showed significant increases (p<.05) in the rate of change of scapular angles in the upward/downward rotation and the retraction/protraction direction under the loaded conditions, whereas users with paraplegia only showed difference in the retraction/protraction rotation direction. Overall both user populations moved towards position of increased downward rotation, anterior tilt and protraction with increase in load hence increasing the risk of impingement. This experiment adds depth to our understanding of dynamic scapular kinematics during wheelchair propulsion under different loading conditions and differences in scapular control between users with paraplegia and tetraplegia.
在上肢肌肉进行重复性负荷活动，如轮椅推进时，周围肌肉会疲劳，导致节段运动出现不规则。本研究的目的是确定增加负荷对截瘫和四肢瘫患者肩胛骨运动学的影响。通过电磁运动跟踪系统（100Hz）和力感应推把（200Hz），对 18 名参与者（11 名截瘫和 7 名四肢瘫）进行了数据收集。参与者在无负荷和常规推进速度的负荷条件下进行推进。平均而言，实验方案会产生 60N 的力增加。四肢瘫患者在负荷条件下，肩胛骨的上/下旋转和回缩/前伸方向的角度变化率显著增加（p<.05），而截瘫患者仅在回缩/前伸旋转方向上存在差异。总体而言，随着负荷的增加，两个患者群体都向增加的下旋转、前倾斜和前伸位置移动，从而增加了撞击的风险。本实验加深了我们对不同负荷条件下轮椅推进过程中肩胛骨动力学以及截瘫和四肢瘫患者肩胛骨控制差异的理解。
