Department of Physical Therapy - Program in Exercise & Rehabilitation Science, Marquette University, Cramer Hall 004B, 604 N. 16th St. 004B, Milwaukee, WI, 53233, USA.
School of Kinesiology, University of Michigan, CCRB 4745G, 401 Washtenaw Ave., Ann Arbor, MI, 48109-2214, USA; Orthopaedic and Rehabilitation Biomechanics Laboratory, University of Michigan, CCRB 4745G, 401 Washtenaw Ave., Ann Arbor, MI, 48109-2214, USA.
Gait Posture. 2020 Oct;82:203-208. doi: 10.1016/j.gaitpost.2020.09.006. Epub 2020 Sep 12.
People with chronic ankle instability (CAI) exhibit neuromuscular deficits. Previous studies, however, only investigated magnitudes of muscle activation and not the time-frequency domain.
Do people with CAI exhibit differences in muscle activation patterns in the time-frequency domain during landing, anticipated cutting, and unanticipated cutting compared to matched controls?
Eleven people with CAI and eleven healthy matched controls (CON) performed landing, anticipated cutting, and unanticipated cutting as surface EMG of the lateral gastrocnemius, medial gastrocnemius, fibularis longus, soleus, and tibialis anterior were recorded. The time-frequency domain of surface EMG data was analyzed with wavelet transformations and principal component analysis (PCA), PC scores were compared across group, task, and muscle with three-way ANOVAs.
The PCA extracted two PCs that captured the overall magnitude (PC1) of wavelet intensities across the time-frequency domain and a shift among the range of frequencies (PC2) where wavelet intensities were most prominent. A main effect for group indicated that people with CAI demonstrated smaller (p = 0.009) PC1 scores than people in the CON group across all muscles and tasks. An interaction between group and task indicated that people in the CAI group exhibited smaller (p = 0.041) PC2 scores than people in the CON group during only anticipated cutting.
People with CAI exhibited neuromuscular deficits in the time-frequency domain of EMG during dynamic tasks. These deficits appear to reflect a neuromuscular strategy characterized by the recruitment of fewer motor units in ankle muscles regardless of task, and an inability to scale the recruitment of motor units in the frequency domain in response to different task demands. Rehabilitation for people with CAI should consider that this population exhibits differences in neuromuscular control that exist not only in the overall magnitudes, but also in the time-frequency domain, of muscle activation patterns.
患有慢性踝关节不稳定（CAI）的人表现出神经肌肉缺陷。然而，以前的研究仅调查了肌肉激活的幅度，而没有调查时频域。
与匹配的对照组相比，患有 CAI 的人在着陆、预期切割和意外切割时的肌肉激活模式在时频域是否存在差异？
11 名 CAI 患者和 11 名健康匹配的对照组（CON）进行着陆、预期切割和意外切割，同时记录外侧腓肠肌、内侧腓肠肌、腓骨长肌、比目鱼肌和胫骨前肌的表面肌电图。使用小波变换和主成分分析（PCA）对表面肌电图数据的时频域进行分析，通过三因素方差分析比较组间、任务间和肌肉间的 PC 得分。
PCA 提取了两个 PC，分别捕获了时频域中整个小波强度（PC1）和频率范围（PC2）中最显著的强度变化。组间的主要效应表明，CAI 患者在所有肌肉和任务中，PC1 得分均显著小于 CON 组（p = 0.009）。组间和任务间的交互作用表明，CAI 患者在仅预期切割时，PC2 得分显著小于 CON 组（p = 0.041）。
患有 CAI 的人在动态任务中表现出肌肉 EMG 的时频域神经肌肉缺陷。这些缺陷似乎反映了一种神经肌肉策略，其特征是无论任务如何，踝关节肌肉募集的运动单位较少，并且无法根据不同的任务需求调整运动单位在频域的募集。CAI 患者的康复应考虑到该人群在肌肉激活模式的时频域中不仅存在整体幅度的差异，而且存在神经肌肉控制的差异。
