Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
J Electromyogr Kinesiol. 2014 Jun;24(3):430-6. doi: 10.1016/j.jelekin.2014.03.006. Epub 2014 Mar 28.
The aim of the current study was to analyze the activation characteristics and potential compartmentalization of the latissimus dorsi (LD) muscle during common maximal voluntary isometric contractions (MVICs) and functional dynamic tasks. Surface electromyography (sEMG) was used to measure activation magnitudes from four electrode sites (referenced to the T10, T12, L1 & L4 LD vertebral origins) across the fanning muscle belly of the LD. In addition, EMG waveforms were cross-correlated to study temporal activation timing between electrode sites (T10-T12, T12-L1, L1-L4 & T10-L4). The MVICs that were tested included a humeral adduction, humeral adduction with internal rotation, a chest-supported row and a humeral extension. Dynamic movements included sagittal lift/lowers from the floor to knee, knee to hip and hip to shoulder. No magnitude-based (p=0.6116) or temporal-based differences were observed between electrode sites during the MVIC trials. During dynamic movements no temporal-based, but some magnitude-based differences between electrode sites were observed to be present; these differences were small in magnitude and were observed for both the maximum (p=0.0002) and mean (p=0.0002) EMG magnitudes. No clear pattern of compartmentalization was uncovered in the contractions studied here. In addition to these findings, it was determined that the most effective MVIC technique for LD EMG normalization purposes was a chest-supported row MVIC, paired with a T12 electrode site.
本研究旨在分析背阔肌（LD）在常见最大自主等长收缩（MVIC）和功能性动态任务中的激活特征和潜在的节段化。表面肌电图（sEMG）用于测量四个电极位置（参考 T10、T12、L1 和 L4 LD 椎骨起源）在 LD 扇形肌肉腹部的激活幅度。此外，还对肌电图波形进行了互相关分析，以研究电极位置之间的时间激活定时（T10-T12、T12-L1、L1-L4 和 T10-L4）。测试的 MVIC 包括肱骨内收、肱骨内收伴内旋、胸部支撑划船和肱骨伸展。动态运动包括从地板到膝盖、膝盖到臀部和臀部到肩部的矢状面升降。在 MVIC 试验中，电极位置之间没有基于幅度（p=0.6116）或基于时间的差异。在动态运动中，虽然没有基于时间的差异，但观察到电极位置之间存在一些基于幅度的差异；这些差异的幅度很小，在最大（p=0.0002）和平均（p=0.0002）肌电图幅度上都有观察到。在研究的收缩中，没有发现明显的节段化模式。除了这些发现，还确定了用于 LD EMG 归一化目的的最有效 MVIC 技术是胸部支撑划船 MVIC，与 T12 电极位置配对。
