BACKGROUND Muscle synergies analysis can provide a deep understanding of motor impairment after stroke and of changes after rehabilitation. In this study, the neuro-mechanical analysis of leg cycling was used to longitudinally investigate the motor recovery process coupled with cycling training augmented by Functional Electrical Stimulation (FES) in subacute stroke survivors. METHODS Subjects with ischemic subacute stroke participated in a 3-week training of FES-cycling with visual biofeedback plus usual care. Participants were evaluated before and after the intervention through clinical scales, gait spatio-temporal parameters derived from an instrumented mat, and a voluntary pedaling test. Biomechanical metrics (work produced by the two legs, mechanical effectiveness and symmetry indexes) and bilateral electromyography from 9 leg muscles were acquired during the voluntary pedaling test. To extract muscles synergies, the Weighted Nonnegative Matrix Factorization algorithm was applied to the normalized EMG envelopes. Synergy complexity was measured by the number of synergies required to explain more than 90% of the total variance of the normalized EMG envelopes and variance accounted for by one synergy. Regardless the inter-subject differences in the number of extracted synergies, 4 synergies were extracted from each patient and the cosine-similarity between patients and healthy weight vectors was computed. RESULTS Nine patients (median age of 75 years and median time post-stroke of 2 weeks) were recruited. Significant improvements in terms of clinical scales, gait parameters and work produced by the affected leg were obtained after training. Synergy complexity well correlated to the level of motor impairment at baseline, but it did not change after training. We found a significant improvement in the similarity of the synergy responsible of the knee flexion during the pulling phase of the pedaling cycle, which was the mostly compromised at baseline. This improvement may indicate the re-learning of a more physiological motor strategy. CONCLUSIONS Our findings support the use of the neuro-mechanical analysis of cycling as a method to assess motor recovery after stroke, mainly in an early phase, when gait evaluation is not yet possible. The improvement in the modular coordination of pedaling correlated with the improvement in motor functions and walking ability achieved at the end of the intervention support the role of FES-cycling in enhancing motor re-learning after stroke but need to be confirmed in a controlled study with a larger sample size. TRIAL REGISTRATION ClinicalTrial.gov, NCT02439515. Registered on May 8, 2015, .

中文翻译：

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亚急性中风幸存者进行功能性电刺激增强训练后腿部循环肌肉协同作用的变化：一项试点研究。


背景技术肌肉协同分析可以深入了解中风后的运动障碍和康复后的变化。在这项研究中，利用腿部自行车的神经力学分析来纵向研究亚急性中风幸存者的运动恢复过程以及通过功能性电刺激（FES）增强的自行车训练。方法 患有缺血性亚急性中风的受试者参加了为期 3 周的 FES 循环训练，包括视觉生物反馈加常规护理。通过临床量表、来自仪表垫的步态时空参数以及自愿踩踏测试，对参与者在干预前后进行了评估。在自愿踩踏测试期间获得了生物力学指标（两条腿产生的功、机械效率和对称性指数）和 9 条腿部肌肉的双侧肌电图。为了提取肌肉协同作用，将加权非负矩阵分解算法应用于归一化的肌电图包络。协同复杂性通过解释标准化肌电图包络总方差的 90% 以上所需的协同数量以及由一个协同作用解释的方差来衡量。无论提取的协同效应数量存在受试者间差异，从每位患者中提取 4 个协同效应，并计算患者和健康体重向量之间的余弦相似度。结果 招募了 9 名患者（中位年龄 75 岁，中风后中位时间为 2 周）。训练后，受影响腿的临床尺度、步态参数和做功得到了显着改善。协同复杂性与基线时的运动障碍水平密切相关，但训练后并没有改变。 我们发现，在蹬车周期的拉动阶段，负责膝关节屈曲的协同作用的相似性有了显着改善，而这在基线时受到了最大程度的损害。这种改进可能表明重新学习更符合生理学的运动策略。结论我们的研究结果支持使用自行车的神经力学分析作为评估中风后运动恢复的方法，主要是在早期阶段，当时还无法进行步态评估。踩踏模块协调性的改善与干预结束时运动功能和步行能力的改善相关，支持 FES 循环在中风后增强运动再学习中的作用，但需要在对照研究中得到证实更大的样本量。试验注册 ClinicalTrial.gov，NCT02439515。注册时间：2015年5月8日。