Hodges P W, Gurfinkel V S, Brumagne S, Smith T C, Cordo P C
Prince of Wales Medical Research Institute and University of New South Wales, Sydney, Australia.
Exp Brain Res. 2002 Jun;144(3):293-302. doi: 10.1007/s00221-002-1040-x. Epub 2002 Apr 13.
This study evaluated the extent to which movement of the lower limbs and pelvis may compensate for the disturbance to posture that results from respiratory movement of the thorax and abdomen. Motion of the neck, pelvis, leg and centre of pressure (COP) were recorded with high resolution in conjunction with electromyographic activity (EMG) of flexor and extensor muscles of the trunk and hip. Respiration was measured from ribcage motion. Subjects breathed quietly, and with increased volume due to hypercapnoea (as a result of breathing with increased dead-space) and a voluntary increase in respiration. Additional recordings were made during apnoea. The relationship between respiration and other parameters was measured from the correlation between data in the frequency domain (i.e. coherence) and from time-locked averages triggered from respiration. In quiet standing, small angular displacements ( approximately 0.5 degrees ) of the trunk and leg were identified in raw data. Correspondingly, there were peaks in the power spectra of the angular movements and EMG. While body movement and EMG were coherent with respiration (>0.5), the coherence between respiration and COP displacement was low (<0.2). The amplitude of movement and coherence was increased when respiration was increased. The present data suggest that the postural disturbance that results from respiratory movement is matched, at least partly, and counteracted by small angular displacements of the lower trunk and lower limbs. Thus, stability in quiet stance is dependent on movement of multiple body segments and control of equilibrium cannot be reduced to control of a single joint.
本研究评估了下肢和骨盆的运动在多大程度上可以补偿由胸部和腹部呼吸运动引起的姿势干扰。使用高分辨率记录颈部、骨盆、腿部和压力中心(COP)的运动,并结合躯干和髋部屈伸肌的肌电图活动(EMG)。通过胸廓运动测量呼吸。受试者安静呼吸,以及因高碳酸血症(由于死腔增加呼吸导致)和呼吸的自主增加而使呼吸量增加时进行测量。在呼吸暂停期间进行额外记录。通过频域数据之间的相关性(即相干性)以及由呼吸触发的时间锁定平均值来测量呼吸与其他参数之间的关系。在安静站立时,在原始数据中识别出躯干和腿部的小角度位移(约0.5度)。相应地,角度运动和肌电图的功率谱出现峰值。虽然身体运动和肌电图与呼吸相干(>0.5),但呼吸与COP位移之间的相干性较低(<0.2)。当呼吸增加时,运动幅度和相干性增加。目前的数据表明,呼吸运动引起的姿势干扰至少部分地被下躯干和下肢的小角度位移所匹配和抵消。因此,安静站立时的稳定性取决于多个身体节段的运动,并且平衡控制不能简化为单个关节的控制。