Coordination of functionally coupled muscles is a key aspect of movement execution. Demands on coordinative control increase with the number of involved muscles and joints, as well as with differing movement periods within a given motor sequence. While previous research has provided evidence concerning inter- and intramuscular synchrony in isolated movements, compound movements remain largely unexplored. With this study, we aimed to uncover intermuscular synchrony between homologous muscles during bipedal squatting (BpS) at multiple frequency bands (alpha, beta, and gamma) utilizing intermuscular coherence (IMC) analyses. For this purpose, participants performed bipedal squats without additional load, which were divided into three distinct movement periods. Surface electromyography (EMG) was recorded from 4 homologous muscle pairs representing prime movers during bipedal squatting. We found significant IMC at all frequency bands for all homologous muscles. Importantly, we provide novel evidence that IMC magnitudes differ between movement periods in beta and gamma bands, as well as between homologous muscle pairs across all frequency bands. Here, beta and gamma IMC magnitudes were highest during eccentric movement periods, whereas we did not find movement related modulations for alpha IMC magnitudes. This finding thus indicates increased integration of afferent integration during eccentric movement periods. Collectively, our results shed light on intermuscular synchronization during bipedal squatting, as we provide evidence that central nervous processing of intermuscular functioning is achieved through task-dependent modulations of common neural input to homologous muscles.

中文翻译：

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双足蹲动和静态运动期间同源肌肉之间的肌间连贯性。

功能耦合肌肉的协调是运动执行的一个关键方面。对协调控制的要求随着涉及的肌肉和关节的数量增加，以及在给定运动序列内的不同运动周期而增加。虽然之前的研究提供了关于孤立运动中肌肉间和肌肉内同步的证据，但复合运动在很大程度上仍未得到探索。通过这项研究，我们旨在利用肌间相干 (IMC) 分析，在多个频段（α、β 和 γ）下发现双足蹲下 (BpS) 期间同源肌肉之间的肌间同步。为此，参与者在没有额外负荷的情况下进行双足深蹲，分为三个不同的运动阶段。表面肌电图 (EMG) 是从代表双足蹲下原动机的 4 对同源肌肉中记录下来的。我们发现所有同源肌肉在所有频段都有显着的 IMC。重要的是，我们提供了新的证据表明 IMC 幅度在 beta 和 gamma 波段的运动周期之间以及所有频段的同源肌肉对之间存在差异。在这里，β 和伽马 IMC 幅度在偏心运动期间最高，而我们没有发现 α IMC 幅度的运动相关调制。因此，这一发现表明在离心运动期间传入整合的整合增加。总的来说，我们的结果揭示了双足下蹲期间的肌间同步，