University of Utah, Department of Health and Kinesiology, Salt Lake City, UT, USA.
University of Utah, Department of Health and Kinesiology, Salt Lake City, UT, USA.
J Biomech. 2023 Apr;151:111544. doi: 10.1016/j.jbiomech.2023.111544. Epub 2023 Mar 12.
Humans regularly follow curvilinear trajectories during everyday ambulation. However, globally-defined and locally-defined reference frames fall out of alignment during turning gait, which complicates spatiotemporal and biomechanical analyses. Thus, the choice of the locally-defined reference frame is an important methodological consideration. This study investigated how different definitions of reference frame change the results and interpretations of common gait measures during turning. Nine healthy adults completed two walking trials around a circular track. Kinematic data were collected via motion capture and used to calculate step length, step width, anteroposterior margin of stability, and mediolateral margin of stability using three different locally-defined reference frames: walkway-fixed, body-fixed, and trajectory-fixed. Linear-mixed effects models compared the effect of reference frame on each gait measure, and the effect of reference frame on conclusions about a known effect of turning gait - asymmetrical stepping patterns. All four gait measures differed significantly across the three reference frames. A significant interaction of reference frame and step type (i.e. inside vs outside step) on step length (p < 0.001), anteroposterior margin of stability (p < 0.001), and mediolateral margin of stability (p < 0.001) indicated conclusions about asymmetry differed based on the choice of reference frame. The choice of reference frame will change the calculated gait measures and may alter the conclusions of studies investigating turning gait. Care should be taken when comparing studies that used different reference frames, as results cannot be easily harmonized. Future studies of turning gait need to justify and detail their choice of reference frame.
人类在日常步行中经常会沿着曲线轨迹行进。然而，在转弯步态中，全局定义和局部定义的参考框架会失去一致性，这使得时空和生物力学分析变得复杂。因此，局部参考框架的选择是一个重要的方法学考虑因素。本研究探讨了不同的参考框架定义如何改变转弯时常见步态测量的结果和解释。9 名健康成年人在圆形轨道上完成了两次步行试验。运动捕捉系统采集了运动学数据，并使用三种不同的局部定义参考框架（步道固定、身体固定和轨迹固定）计算步长、步宽、前后向稳定性和左右向稳定性。线性混合效应模型比较了参考框架对每个步态测量的影响，以及参考框架对转弯步态已知效应（不对称步态模式）结论的影响。三个参考框架下的所有四个步态测量值均有显著差异。参考框架和步型（即内步和外步）对步长（p<0.001）、前后向稳定性（p<0.001）和左右向稳定性（p<0.001）的显著交互作用表明，对不对称性的结论取决于参考框架的选择。参考框架的选择会改变计算出的步态测量值，并可能改变转弯步态研究的结论。在比较使用不同参考框架的研究时应谨慎，因为结果不能轻易协调。未来的转弯步态研究需要证明并详细说明其参考框架的选择。
