The purpose of this study was to clarify the coordination between the trunk and lower limb muscles during sidestep and to compare this coordination before and after fatigue intervention. The intervention was lateral jump until exhaustion. Nonnegative matrix factorization (NMF) was used to extract muscle synergies from electromyography. Subsequently, to compare the muscle synergies, a scalar product that evaluates the coincidence of synergies was calculated. Three muscle synergies were extracted before and after the intervention from the NMF analysis. In accordance with the evaluation of the scalar product, these synergies were the same before and after the intervention. One of these synergies that engaged the internal oblique/transversus abdominis, rectus femoris, and adductor muscle was activated from before landing to midstance during sidestep motion; therefore, this synergy is thought to suppress excessive hip abduction. However, the activation timing of this synergy was delayed after the intervention (, effect size: 0.54, Wilcoxon test). This delay is considered to decrease hip stability. Thus, this change may induce a reduction in hip control function.

中文翻译：

---

疲劳前后侧切过程中模块化控制的比较

这项研究的目的是阐明在进行步伐过程中躯干和下肢肌肉之间的协调性，并比较疲劳干预前后的协调性。干预是横向跳跃直到筋疲力尽。非负矩阵分解（NMF）用于从肌电图提取肌肉协同作用。随后，为了比较肌肉协同作用，计算了评估协同作用一致性的标量积。在NMF分析干预之前和之后，提取了三种肌肉协同作用。根据标量产品的评估，干预前后这些协同作用是相同的。这些与内斜肌/腹横肌，股直肌，内收肌在侧身运动中从着陆前到中位被激活；因此，这种协同作用被认为可以抑制过度的髋关节外展。但是，在干预之后，这种协同作用的激活时间有所延迟（，效果大小：0.54，Wilcoxon测试）。这种延迟被认为降低了髋关节的稳定性。因此，这种变化可能导致髋关节控制功能降低。