PhD Program in Rehabilitation Science, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA.
School of Physical Therapy, Marshall University, Huntington, WV, USA.
Exp Brain Res. 2022 Feb;240(2):481-490. doi: 10.1007/s00221-021-06270-x. Epub 2021 Nov 20.
Ability of the human body to regain balance after being externally perturbed is important in the maintenance of vertical posture. The goal of this study was to investigate trunk and leg muscle response to external perturbation while sitting on a stool with varying seat inclinations. Ten healthy subjects were required to receive a perturbation applied to the upper body while sitting on an adjustable stool with 0°, 10° forward or 10° backward inclination of the seat and without footrest and leg support. Electromyographic activities of the trunk and leg muscles and center of pressure displacements were recorded and analyzed during the anticipatory (APA) and compensatory (CPA) phases of postural control. APAs and CPAs were generated in response to an external perturbation. Delays in the onset of anticipatory muscle activity were seen when seated on the inclined seat compared to sitting on the horizontal seat (p < 0.05). To maintain balance after a perturbation, participants activated the trunk and thigh muscles, the activity of which was modulated to a greater degree than that of leg muscles. Moreover, they utilized co-contraction of muscles as the main mechanism of balance control in sitting. Furthermore, there was no effect of a seat inclination on COP displacements. The outcome provides a background for future investigations of the effect of seat inclination on control of balance in sitting.
人体在外力干扰后恢复平衡的能力对于维持垂直姿势非常重要。本研究的目的是研究在坐姿下，座椅倾斜度不同时，躯干和腿部肌肉对外力干扰的反应。10 名健康受试者被要求坐在可调节的座椅上，座椅的倾斜度分别为 0°、10°前倾或 10°后倾，不使用脚凳和腿部支撑，接受上半身的外力干扰。在姿势控制的预期（APA）和补偿（CPA）阶段，记录和分析了躯干和腿部肌肉的肌电图活动和中心压力位移。APAs 和 CPAs 是对外力干扰的反应而产生的。与坐在水平座椅相比，坐在倾斜座椅上时，预备性肌肉活动的起始延迟（p<0.05）。为了在受到干扰后保持平衡，参与者激活了躯干和大腿肌肉，其活动被调节到比腿部肌肉更大的程度。此外，他们利用肌肉的共同收缩作为坐姿平衡控制的主要机制。此外，座椅倾斜度对 COP 位移没有影响。研究结果为进一步研究座椅倾斜度对坐姿平衡控制的影响提供了背景。
