Kumar S, Narayan Y
Department of Physical Therapy, University of Alberta, Edmonton, Canada.
Ergonomics. 2001 Jun 20;44(8):795-813. doi: 10.1080/00140130110045802.
The main objective of the study was to measure the magnitude and pattern of electromyographic (EMG) activity of the trunk muscles in combined motions of flexion-rotation and extension-rotation. Another objective of the study was to determine the torque-EMG Root Mean Square (RMS) relationship in these activities for predictive purposes. Nineteen normal young adult subjects who met the inclusion criteria were fitted with 12 pairs of surface electrodes on their external and internal oblique, rectus abdominis, latissimus dorsi, and erector spinae muscles at T10 and L3 levels bilaterally. Using a Posture Stabilizing Platform (PSP) they were fixed in 40 degrees flexed and 40 degrees right rotated trunk postures. From this posture subjects attempted an isometric extension-rotation and flexion-rotation in the plane defined by the asymmetrical postural axis in the plane of rotation of the assumed posture. Contractions of 25, 50 and 75% of the previously measured maximal voluntary contraction (MVC) were attempted using a Static Dynamic Strength Tester (SDST) and force monitor attached by a steel cable to a rigid thoracic harness worn by the subjects. The data were acquired at 1 kHz. Descriptive statistics were calculated and ANOVA, correlation and regression analyses were carried out. With linear increase in flexion-rotation and extension-rotation torque, the magnitude of total EMG output increased exponentially. In flexion-rotation the EMG magnitude of all muscles increased with increasing grades of contraction (% of MVC). However, in proportional terms, the magnitude of erector spinae EMG declined. In extension-rotation there was a reversal of roles between the ventral and dorsal muscles compared to the flexion-rotation. For the two genders, all muscles and grades of contractions were significantly different from each other (p<0.01). There was a significant but modest correlation between EMG and torque (r = 0.25 to 0.54; p<0.01). The regressions were significant (p<0.01) and explained up to 74% of the variance in torque. The flexion-rotation and extension-rotation torques can be predicted with only a moderate accuracy.
该研究的主要目的是测量在屈曲-旋转和伸展-旋转联合运动中躯干肌肉的肌电图（EMG）活动的幅度和模式。该研究的另一个目的是确定这些活动中扭矩-EMG均方根（RMS）关系，以用于预测目的。19名符合纳入标准的正常年轻成年受试者在其双侧T10和L3水平的腹外斜肌、腹内斜肌、腹直肌、背阔肌和竖脊肌上安装了12对表面电极。使用姿势稳定平台（PSP），他们被固定在躯干40度屈曲和40度右旋的姿势。从这个姿势开始，受试者在由假定姿势旋转平面中的不对称姿势轴所定义的平面内尝试进行等长伸展-旋转和屈曲-旋转。使用静态动态力量测试仪（SDST）和通过钢缆连接到受试者佩戴的刚性胸背带的力监测器，尝试进行先前测量的最大自主收缩（MVC）的25%、50%和75%的收缩。数据以1kHz采集。计算描述性统计量，并进行方差分析、相关性和回归分析。随着屈曲-旋转和伸展-旋转扭矩的线性增加，总EMG输出幅度呈指数增加。在屈曲-旋转中，所有肌肉的EMG幅度随着收缩等级（MVC的百分比）的增加而增加。然而，按比例而言，竖脊肌EMG的幅度下降。与屈曲-旋转相比，在伸展-旋转中腹侧和背侧肌肉之间的作用发生了逆转。对于两种性别，所有肌肉和收缩等级彼此之间均存在显著差异（p<0.01）。EMG与扭矩之间存在显著但适度的相关性（r = 0.25至0.54；p<0.01）。回归具有显著性（p<0.01），并解释了高达74%的扭矩方差。屈曲-旋转和伸展-旋转扭矩只能以中等精度进行预测。
