Dolan P, Adams M A
Department of Anatomy, University of Bristol, Park Row, U.K.
J Biomech. 1993 Apr-May;26(4-5):513-22. doi: 10.1016/0021-9290(93)90013-5.
The relationship between EMG activity and extensor moment generation in the erector spinae muscles was investigated under isometric and concentric conditions. The full-wave rectified and averaged EMG signal was recorded from skin-surface electrodes located over the belly of the erector spinae at the levels of T10 and L3, and compared with measurements of extensor moment. The effects of muscle length and contraction velocity were studied by measuring the overall curvature (theta) and rate of change of curvature (d theta/dt) of the lumbar spine in the sagittal plane, using the '3-Space Isotrak' system. Isometric contractions were investigated with the subjects pulling up on a load cell attached to the floor. Hand height was varied to produce different amounts of lumbar flexion, as indicated by changes in lumbar curvature. The extensor moment was found to be linearly related to EMG activity, and the 'gradient' and 'intercept' of the relationship were themselves dependent upon the lumbar curvature at the time of testing. Concentric contractions were investigated with the subjects extending from a seated toe-touching position, at various speeds, while the torque exerted on the arm of a Cybex dynamometer was continuously measured. Under these conditions the EMG signal (E) was higher than the isometric signal (E0) associated with the same torque. E and E0 were related as follows: E0 = E/(1 + A d theta/dt), where A = 0.0014 exp (0.045P) and P = percentage lumbar flexion. This equation was used to correct the EMG data for the effect of contraction velocity. The corrected data were then used, in conjunction with the results of the isometric calibrations, to calculate the extensor moment generated by the erector spinae muscles during bending and lifting activities. The extensor moment can itself be used to calculate the compressive force acting on the lumbar spine.
在等长和向心收缩条件下，研究了竖脊肌肌电图（EMG）活动与伸肌力矩产生之间的关系。从位于T10和L3水平竖脊肌肌腹上方的皮肤表面电极记录全波整流和平均后的EMG信号，并与伸肌力矩测量值进行比较。使用“3-Space Isotrak”系统，通过测量腰椎矢状面的整体曲率（θ）和曲率变化率（dθ/dt），研究肌肉长度和收缩速度的影响。在等长收缩研究中，让受试者向上拉动连接在地板上的测力传感器。手部高度变化以产生不同程度的腰椎前屈，如腰椎曲率变化所示。发现伸肌力矩与EMG活动呈线性相关，并且这种关系的“斜率”和“截距”本身取决于测试时的腰椎曲率。在向心收缩研究中，让受试者从坐姿触趾位置以不同速度伸展，同时连续测量施加在Cybex测力计臂上的扭矩。在这些条件下，EMG信号（E）高于与相同扭矩相关的等长信号（E0）。E和E0的关系如下：E0 = E/(1 + A dθ/dt)，其中A = 0.0014 exp (0.045P)，P = 腰椎前屈百分比。该方程用于校正收缩速度对EMG数据的影响。然后，将校正后的数据与等长校准结果结合使用，以计算竖脊肌在弯曲和提起活动期间产生的伸肌力矩。伸肌力矩本身可用于计算作用在腰椎上的压缩力。
