Department of Training and Movement Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
Berlin School of Movement Science, Humboldt-Universität zu Berlin, Berlin, Germany.
PLoS One. 2022 Jun 3;17(6):e0269417. doi: 10.1371/journal.pone.0269417. eCollection 2022.
There is increasing evidence that including sex as a biological variable is of crucial importance to promote rigorous, repeatable and reproducible science. In spite of this, the body of literature that accounts for the sex of participants in human locomotion studies is small and often produces controversial results. Here, we investigated the modular organization of muscle activation patterns for human locomotion using the concept of muscle synergies with a double purpose: i) uncover possible sex-specific characteristics of motor control and ii) assess whether these are maintained in older age. We recorded electromyographic activities from 13 ipsilateral muscles of the lower limb in young and older adults of both sexes walking (young and old) and running (young) on a treadmill. The data set obtained from the 215 participants was elaborated through non-negative matrix factorization to extract the time-independent (i.e., motor modules) and time-dependent (i.e., motor primitives) coefficients of muscle synergies. We found sparse sex-specific modulations of motor control. Motor modules showed a different contribution of hip extensors, knee extensors and foot dorsiflexors in various synergies. Motor primitives were wider (i.e., lasted longer) in males in the propulsion synergy for walking (but only in young and not in older adults) and in the weight acceptance synergy for running. Moreover, the complexity of motor primitives was similar in younger adults of both sexes, but lower in older females as compared to older males. In essence, our results revealed the existence of small but defined sex-specific differences in the way humans control locomotion and that these are not entirely maintained in older age.
越来越多的证据表明，将性别作为生物学变量纳入其中对于促进严谨、可重复和可复制的科学研究至关重要。尽管如此，关于人类运动研究中参与者性别的文献数量很少，并且经常产生有争议的结果。在这里，我们使用肌肉协同的概念研究了人类运动的肌肉激活模式的模块化组织，目的有二：i）揭示运动控制的可能性别特异性特征，ii）评估这些特征是否在老年时保持。我们记录了 13 名年轻和老年男女参与者在跑步机上行走（年轻和老年）和跑步（年轻）时的下肢 13 对同侧肌肉的肌电活动。从 215 名参与者获得的数据通过非负矩阵分解进行了详细分析，以提取肌肉协同的时间独立（即运动模块）和时间依赖（即运动原语）系数。我们发现运动控制存在稀疏的性别特异性调节。运动模块显示出不同的协同作用中髋伸肌、膝伸肌和足背屈肌的贡献不同。在行走的推进协同作用中（但仅在年轻成年人中，而不在老年成年人中）和跑步的承重协同作用中，男性的运动原语更宽（即持续时间更长）。此外，男女年轻成年人的运动原语复杂性相似，但老年女性的复杂性低于老年男性。从本质上讲，我们的研究结果表明，人类控制运动的方式存在微小但明确的性别特异性差异，而这些差异在老年时并非完全保持。
