Tsai Wei-Chi, Lien Hen-Yu, Liu Wen-Yu, Guo Siang-Lan, Lin Yang-Hua, Yang Tsui-Fen
School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Physical Medicine and Rehabilitation, Taipei Veterans General Hospital, Taipei, Taiwan.
School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
J Electromyogr Kinesiol. 2018 Dec;43:21-27. doi: 10.1016/j.jelekin.2018.08.005. Epub 2018 Aug 27.
Clinicians frequently incorporate unstable sitting devices into training plans for improving proximal postural muscle control; however, the effect of unstable sitting conditions on postural adjustments during dynamic activities has not been fully explored. The aim of this study was to characterize early postural adjustments (EPAs) and anticipatory postural adjustments (APAs) under stable and unstable sitting conditions. Using a cross-sectional laboratory study design, 13 healthy college student volunteers used their dominant hand to reach forward and push a target under stable and unstable sitting conditions; subjects sat on an air-filled rubber cushion for the unstable condition. EPAs and APAs were quantified by recording muscle activation of the trunk and lower extremity muscles using electromyography (EMG). The center of pressure (COP) was measured using a force plate. The resulting EMG integral of the ipsilateral gastrocnemius muscle was larger during the EPA phase and smaller during the APA phase under unstable conditions (p = 0.014 and p = 0.041, respectively). COP amplitude in the anterior-posterior direction, path length, and velocity, was larger during the APA phase (p = 0.035, p = 0.023, and 0.023, respectively). This suggests greater distal muscle activation during EPAs in unstable sitting conditions, specifically in the ipsilateral gastrocnemius muscle. In addition, APAs adjusted by reducing the activity of the ipsilateral gastrocnemius muscle and increasing the anterior-posterior shift in the COP to compensate for the expected additional perturbation due to an unstable surface.
临床医生经常将不稳定坐姿装置纳入训练计划，以改善近端姿势肌肉控制；然而，不稳定坐姿条件对动态活动中姿势调整的影响尚未得到充分研究。本研究的目的是描述稳定和不稳定坐姿条件下的早期姿势调整（EPA）和预期姿势调整（APA）。采用横断面实验室研究设计，13名健康大学生志愿者在稳定和不稳定坐姿条件下用优势手向前伸展并推动目标；在不稳定条件下，受试者坐在充气橡胶垫上。通过使用肌电图（EMG）记录躯干和下肢肌肉的肌肉激活来量化EPA和APA。使用测力板测量压力中心（COP）。在不稳定条件下，同侧腓肠肌的EMG积分在EPA阶段较大，在APA阶段较小（分别为p = 0.014和p = 0.041）。在APA阶段，COP在前后方向上的幅度、路径长度和速度较大（分别为p = 0.035、p = 0.023和0.023）。这表明在不稳定坐姿条件下的EPA期间，特别是同侧腓肠肌中，远端肌肉激活更大。此外，APA通过降低同侧腓肠肌的活动并增加COP在前后方向上的移动来进行调整，以补偿由于表面不稳定而预期的额外扰动。
