Kumar S, Narayan Y
Department of Physical Therapy, University of Alberta, Edmonton, Canada.
J Electromyogr Kinesiol. 1998 Aug;8(4):257-67.
Axial rotation of the trunk is commonly associated with back injury and pain. However, the behaviour of trunk muscles in axial rotation is poorly understood. The objective of this study was to measure spectral parameters from the EMG of erector spinae at T10 and L3 levels, latissimus dorsi, external and internal oblique, rectus abdominis and pectoralis major muscles bilaterally in a standardized repeatable axial rotation at 60% MVC to fatigue. Twelve young and healthy subjects were recruited after screening for musculoskeletal disorders. Surface electrodes were applied to the named seven trunk muscles bilaterally. Subjects were seated in the device called Axial Rotation Tester and stabilized such that they could rotate only their thoracolumbar spine. Other motions were prevented. Subjects held 60% of their MVC for a period of 2 min. Samples (2.1 s) were obtained at every 10 s interval at a sampling frequency of 1 KHz. Samples were subjected to FFT analysis. The total power and the median frequencies were analyzed. The median frequency for different muscles were different (p < 0.001). The slopes of decline of the median frequencies of the agonists were different for different muscles (p < 0.001). This differential fatiguing rate could conceivably create a force imbalance potentiating back injury.
躯干的轴向旋转通常与背部损伤和疼痛相关。然而，人们对躯干肌肉在轴向旋转时的行为了解甚少。本研究的目的是在以60%最大自主收缩（MVC）进行标准化可重复轴向旋转至疲劳的过程中，双侧测量T10和L3水平竖脊肌、背阔肌、腹外斜肌、腹内斜肌、腹直肌和胸大肌肌电图的频谱参数。在对肌肉骨骼疾病进行筛查后，招募了12名年轻健康的受试者。将表面电极双侧应用于上述七块躯干肌肉。受试者坐在名为轴向旋转测试仪的设备中并固定，使其只能旋转胸腰椎脊柱。防止其他运动。受试者保持60%的MVC持续2分钟。以1kHz的采样频率每隔10秒获取一次样本（2.1秒）。对样本进行快速傅里叶变换（FFT）分析。分析总功率和中位数频率。不同肌肉的中位数频率不同（p<0.001）。不同肌肉的主动肌中位数频率下降斜率不同（p<0.001）。这种不同的疲劳率可能会导致力量失衡，增加背部受伤的可能性。
