Institute of Design, Robotics, and Optimisation, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom.
Department of Electronic and Electrical Engineering, University of Bath, Bath, United Kingdom.
Hum Mov Sci. 2020 Feb;69:102558. doi: 10.1016/j.humov.2019.102558. Epub 2019 Dec 4.
In a bipedal walk, the human body experiences continuous changes in stability especially during weight loading and unloading transitions which are reported crucial to avoid fall. Prior stability assessment methods are unclear to quantify stabilities during these gait transitions due to methodological and/or measurement limitations. This study introduces Nyquist and Bode methods to quantify stability gait transitional stabilities using the neuromechanical output (CoP) and somatosensory input (GRF) responses. These methods are implemented for five different walking conditions grouped into walking speed and imitated rotational impairments. The trials were recorded with eleven healthy subjects using motion cameras and force platforms. The time rate of change in O/Is illustrated impulsive responses and modelled in the frequency domain. Nyquist and Bode stability methods are applied to quantify stability margins. Stability margins from outputs illustrated loading phases as stable and unloading phases as unstable in all walking conditions. There was a strong intralimb compensatory interaction (p < .001, Spearman correlation) found between opposite limbs. Overall, both walking groups illustrated a decrease (p < .05, Wilcoxon signed-rank test) in stability margins compared with normal/preferred speed walk. Further, stabilities quantified from outputs were found greater in magnitudes than the instability quantified from inputs illustrating the neuromotor balance control ability. These stability outcomes were also compared by applying extrapolated-CoM method. These methods of investigating gait dynamic stability are considered as having important implications for the assessment of ankle-foot impairments, rehabilitation effectiveness, and wearable orthoses.
在双足行走中，人体的稳定性会不断发生变化，尤其是在负重和卸力的转换过程中，这些转换过程对避免跌倒至关重要。由于方法学和/或测量限制，先前的稳定性评估方法无法在这些步态转换期间量化稳定性。本研究引入了奈奎斯特和波特方法，使用神经力学输出（CoP）和躯体感觉输入（GRF）响应来量化步态过渡期间的稳定性。这些方法适用于分为步行速度和模拟旋转损伤的五种不同步行条件。使用运动摄像机和力平台记录了 11 名健康受试者的试验。O/Is 的时间变化率说明了脉冲响应，并在频域中进行了建模。奈奎斯特和波特稳定性方法用于量化稳定性裕度。输出的稳定性裕度表明，在所有步行条件下，负重阶段稳定，卸力阶段不稳定。在相反的肢体之间发现了强烈的肢体间补偿相互作用（p<0.001，Spearman 相关）。总体而言，与正常/偏好速度行走相比，两个步行组的稳定性裕度都有所下降（p<0.05，Wilcoxon 符号秩检验）。此外，与输入量化的不稳定性相比，输出量化的稳定性在幅度上更大，这表明了神经运动平衡控制能力。还通过应用外推 CoM 方法比较了这些稳定性结果。这些研究步态动态稳定性的方法被认为对评估脚踝-足部损伤、康复效果和可穿戴矫形器具有重要意义。
