Yamaguchi Takeshi, Suzuki Akito, Hokkirigawa Kazuo
Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan.
Graduate School of Bioengineering, Tohoku University, Sendai, Miyagi, Japan.
PLoS One. 2017 Jun 22;12(6):e0179817. doi: 10.1371/journal.pone.0179817. eCollection 2017.
This study investigated the required coefficient of friction (RCOF) and the tangent of center of mass (COM)-center of pressure (COP) angle in the mediolateral (ML) and anteroposterior (AP) directions during turning at different walking speeds. Sixteen healthy young adults (8 males and 8 females) participated in this study. The participants were instructed to conduct trials of straight walking and 90° step and spin turns to the right at each of three self-selected speeds (slow, normal, and fast). The ML and AP directions during turning gait were defined using the orientation of the pelvis to construct a body-fixed reference frame. The RCOF values and COM-COP angle tangent in the ML direction during turning at weight acceptance phase were higher than those during straight walking, and those values increased with increasing walking speed. The ML component of the RCOF and COM-COP tangent values during weight acceptance for step turns were higher than those for spin turns. The mean centripetal force during turning tended to increase with an increase in walking speed and had a strong positive correlation with the RCOF values in the ML direction (R = 0.97 during the weight acceptance phase; R = 0.95 during the push-off phase). Therefore, turning, particularly step turn, is likely to cause lateral slip at weight acceptance because of the increased centripetal force compared with straight walking. Future work should test at-risk population and compare with the present results.
本研究调查了不同步行速度下转弯过程中外侧-内侧（ML）和前后（AP）方向所需的摩擦系数（RCOF）以及质心（COM）-压力中心（COP）角的正切值。16名健康的年轻成年人（8名男性和8名女性）参与了本研究。参与者被要求以三种自我选择的速度（慢、正常和快）分别进行直线行走、90°步转和向右转的旋转转弯试验。使用骨盆的方向来定义转弯步态期间的ML和AP方向，以构建一个身体固定参考系。在体重接受阶段转弯时，ML方向的RCOF值和COM-COP角正切值高于直线行走时，并且这些值随着步行速度的增加而增加。步转体重接受期间RCOF的ML分量和COM-COP正切值高于旋转转弯时。转弯过程中的平均向心力倾向于随着步行速度的增加而增加，并且与ML方向的RCOF值具有很强的正相关性（体重接受阶段R = 0.97；蹬离阶段R = 0.95）。因此，与直线行走相比，转弯，特别是步转，由于向心力增加可能在体重接受时导致侧向滑动。未来的工作应该对高危人群进行测试并与目前结果进行比较。
