Hay Dean C, Wachowiak Mark P, Graham Ryan B
1 Nipissing University.
2 University of Ottawa.
J Appl Biomech. 2016 Oct;32(5):526-31. doi: 10.1123/jab.2015-0334. Epub 2016 Aug 19.
Advances in time-frequency analysis can provide new insights into the important, yet complex relationship between muscle activation (ie, electromyography [EMG]) and motion during dynamic tasks. We use wavelet coherence to compare a fundamental cyclical movement (lumbar spine flexion and extension) to the surface EMG linear envelope of 2 trunk muscles (lumbar erector spinae and internal oblique). Both muscles cohere to the spine kinematics at the main cyclic frequency, but lumbar erector spinae exhibits significantly greater coherence than internal oblique to kinematics at 0.25, 0.5, and 1.0 Hz. Coherence phase plots of the 2 muscles exhibit different characteristics. The lumbar erector spinae precedes trunk extension at 0.25 Hz, whereas internal oblique is in phase with spine kinematics. These differences may be due to their proposed contrasting functions as a primary spine mover (lumbar erector spinae) versus a spine stabilizer (internal oblique). We believe that this method will be useful in evaluating how a variety of factors (eg, pain, dysfunction, pathology, fatigue) affect the relationship between muscles' motor inputs (ie, activation measured using EMG) and outputs (ie, the resulting joint motion patterns).
时频分析的进展能够为动态任务期间肌肉激活（即肌电图[EMG]）与运动之间重要但复杂的关系提供新的见解。我们使用小波相干分析，将一种基本的周期性运动（腰椎屈伸）与两块躯干肌肉（竖脊肌和腹内斜肌）的表面肌电图线性包络进行比较。在主要循环频率下，两块肌肉均与脊柱运动学具有相干性，但在0.25、0.5和1.0赫兹时，竖脊肌与运动学的相干性显著高于腹内斜肌。两块肌肉的相干相位图呈现出不同特征。在0.25赫兹时，竖脊肌先于躯干伸展，而腹内斜肌与脊柱运动学同相位。这些差异可能归因于它们作为主要脊柱运动肌（竖脊肌）与脊柱稳定肌（腹内斜肌）所假定的不同功能。我们认为，这种方法将有助于评估多种因素（如疼痛、功能障碍、病理、疲劳）如何影响肌肉的运动输入（即使用肌电图测量的激活）与输出（即产生的关节运动模式）之间的关系。
