Ng J K, Richardson C A, Jull G A
Department of Rehabilitation Sciences, Hong Kong Polytechnic University, Hung Hom, Hong Kong.
Phys Ther. 1997 Sep;77(9):954-61. doi: 10.1093/ptj/77.9.954.
Muscle endurance is an important variable to measure in the assessment of back muscle function. This study investigated the electromyographic (EMG) activity and fatigue patterns of iliocostalis lumborum and multifidus muscles during a trunk holding test.
Sixteen male subjects (mean age = 24.2 years, SD = 4.2, range = 20.6-31.9) without low back pain or known pathology were recruited in the study.
Surface EMG electrodes were used to record the activity of iliocostalis lumborum and mutifidus muscles during a 60-second isometric contraction. To reflect the activity level and fatigue rate of the muscles. EMG amplitude (root mean square [RMS] values) and a frequency variable (median frequency [MF]) were measured.
The multifidus muscle displayed a higher level of activity, initial MF, and normalized MF slope than did the iliocostalis lumborum muscle. There was no difference, however, in the normalized RMS slope between the two muscles. The correlations between the normalized MF slope and the RMS slope of the two muscles were nonsignificant.
This study shows that monitoring frequency changes of the EMG signals may enable therapists to quantify the fatigue changes of individual muscles during the trunk holding test. The higher fatigue rate shown in the multifidus muscle compared with the iliocostalis lumborum muscle may be due to the higher activity level of the multifidus muscle during te trunk holding contraction. This greater activity of the multifidus muscle during the contraction might be explained by the functional differences between these two muscles.
肌肉耐力是评估背部肌肉功能时需要测量的一个重要变量。本研究调查了在躯干保持测试期间，腰髂肋肌和多裂肌的肌电图（EMG）活动及疲劳模式。
本研究招募了16名无腰痛或已知病理状况的男性受试者（平均年龄 = 24.2岁，标准差 = 4.2，范围 = 20.6 - 31.9岁）。
使用表面肌电图电极记录腰髂肋肌和多裂肌在60秒等长收缩期间的活动。为反映肌肉的活动水平和疲劳率，测量了肌电图幅度（均方根[RMS]值）和一个频率变量（中位频率[MF]）。
多裂肌比腰髂肋肌表现出更高的活动水平、初始MF和标准化MF斜率。然而，两块肌肉之间的标准化RMS斜率没有差异。两块肌肉的标准化MF斜率与RMS斜率之间的相关性不显著。
本研究表明，监测肌电图信号的频率变化可能使治疗师能够量化躯干保持测试期间单个肌肉的疲劳变化。与腰髂肋肌相比，多裂肌显示出更高的疲劳率，这可能是由于在躯干保持收缩期间多裂肌的活动水平较高。收缩期间多裂肌的这种更大活动可能由这两块肌肉之间的功能差异来解释。
