Nishida Koji, Hagio Shota, Kibushi Benio, Moritani Toshio, Kouzaki Motoki
Laboratory of Neurophysiology, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto, Japan.
Research Fellow of the Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo, Japan.
PLoS One. 2017 Feb 3;12(2):e0171535. doi: 10.1371/journal.pone.0171535. eCollection 2017.
It is well known that humans run with a fore-foot strike (FFS), a mid-foot strike (MFS) or a rear-foot strike (RFS). A modular neural control mechanism of human walking and running has been discussed in terms of muscle synergies. However, the neural control mechanisms for different foot strike patterns during running have been overlooked even though kinetic and kinematic differences between different foot strike patterns have been reported. Thus, we examined the differences in the neural control mechanisms of human running between FFS and RFS by comparing the muscle synergies extracted from each foot strike pattern during running. Muscle synergies were extracted using non-negative matrix factorization with electromyogram activity recorded bilaterally from 12 limb and trunk muscles in ten male subjects during FFS and RFS running at different speeds (5-15 km/h). Six muscle synergies were extracted from all conditions, and each synergy had a specific function and a single main peak of activity in a cycle. The six muscle synergies were similar between FFS and RFS as well as across subjects and speeds. However, some muscle weightings showed significant differences between FFS and RFS, especially the weightings of the tibialis anterior of the landing leg in synergies activated just before touchdown. The activation patterns of the synergies were also different for each foot strike pattern in terms of the timing, duration, and magnitude of the main peak of activity. These results suggest that the central nervous system controls running by sending a sequence of signals to six muscle synergies. Furthermore, a change in the foot strike pattern is accomplished by modulating the timing, duration and magnitude of the muscle synergy activity and by selectively activating other muscle synergies or subsets of the muscle synergies.
众所周知，人类跑步时会采用前脚掌着地（FFS）、中脚掌着地（MFS）或后脚掌着地（RFS）的方式。关于人类行走和跑步的模块化神经控制机制，已从肌肉协同作用的角度进行了讨论。然而，尽管已经报道了不同着地方式之间的动力学和运动学差异，但跑步过程中不同着地方式的神经控制机制却一直被忽视。因此，我们通过比较跑步过程中从每种着地方式提取的肌肉协同作用，研究了FFS和RFS之间人类跑步神经控制机制的差异。使用非负矩阵分解法从10名男性受试者双侧记录的12块肢体和躯干肌肉在FFS和RFS以不同速度（5 - 15公里/小时）跑步时的肌电图活动中提取肌肉协同作用。在所有条件下均提取出六种肌肉协同作用，并且每种协同作用在一个周期内都有特定的功能和单一的主要活动峰值。FFS和RFS之间、不同受试者之间以及不同速度下的六种肌肉协同作用相似。然而，一些肌肉权重在FFS和RFS之间存在显著差异，特别是在触地前激活的协同作用中，着地腿胫骨前肌的权重。就活动主峰的时间、持续时间和幅度而言，每种着地方式的协同作用激活模式也不同。这些结果表明，中枢神经系统通过向六种肌肉协同作用发送一系列信号来控制跑步。此外，着地方式的改变是通过调节肌肉协同作用活动的时间、持续时间和幅度，以及选择性地激活其他肌肉协同作用或肌肉协同作用的子集来实现的。
