Department of Mechanical Engineering and Intelligent Systems, Graduate School of Informatics and Engineering, University of Electro-Communications, Chofu, Tokyo, Japan.
PLoS One. 2022 Sep 12;17(9):e0274294. doi: 10.1371/journal.pone.0274294. eCollection 2022.
This study aimed to investigate the nature of a specific body manipulation named Suichoku-Ririku (SR) in Japanese martial arts. SR is regarded as a method to change the way of stance and to distort the balance control of the opponent, but its nature and mechanism are unknown. In the present study, we attempted to determine the effect of SR in the cases that a person stood alone (Expt. 1) and that two persons stood in contact (Expt. 2). We compared several center of pressure (COP) measures between the normal stance and SR stance conditions. When participants stood independently (Expt. 1), the COP path length, standard deviation of COP velocity and permutation entropy of the COP increased with the SR stance, which suggested that the SR maneuver destabilized a quiet stance. When two participants stood (with normal stance) in contact by wrist-holding or by a light touch (Expt. 2), their COP motions were correlated with each other, as previously reported. When one of the participants took the SR maneuver, their correlation and mutual information were maintained, denying the view that SR would diminish the interpersonal correlation of body sway. On the other hand, a fluctuation in the COP increased only for the participant taking the SR maneuver, and not for the other participant. This asymmetric effect of the SR maneuver between two participants, irrespective of maintained mutual correlation, suggest that the relationship between balance controls of two participants was partly disrupted. We discuss possible mechanisms for the present results.
本研究旨在探究日本武术中一种名为“推吸离曲（Suichoku-Ririku，SR）”的特定身体操作的本质。SR 被认为是一种改变姿势方式和破坏对手平衡控制的方法，但它的性质和机制尚不清楚。在本研究中，我们试图确定在单人站立（实验 1）和两人接触站立（实验 2）的情况下 SR 的效果。我们比较了正常姿势和 SR 姿势条件下的几个中心压力（COP）指标。当参与者独立站立时（实验 1），COP 路径长度、COP 速度标准差和 COP 排列熵随着 SR 姿势的增加而增加，这表明 SR 操作会使安静的姿势变得不稳定。当两名参与者（以正常姿势）通过腕部握持或轻触接触站立时（实验 2），他们的 COP 运动相互关联，如先前报道的那样。当其中一名参与者进行 SR 操作时，他们的相关性和互信息得以维持，否定了 SR 会减少身体摇晃的人际相关性的观点。另一方面，只有进行 SR 操作的参与者的 COP 波动增加，而另一个参与者则没有。这种 SR 操作在两名参与者之间的不对称影响，不论其相互相关性如何，表明两名参与者的平衡控制之间的关系部分被破坏。我们讨论了本研究结果的可能机制。
