Difference between local and orbital dynamic stability during human walking
Difference between local and orbital dynamic stability during human walking
复制标题
DOI：
10.1115/1.2746383
复制
发表时间：
2007-08-01
影响因子：
1.7
通讯作者：
Kang, Hyun Gu
中科院分区：
文献类型：
--
作者：
Dingwell, Jonathan B.;Kang, Hyun Gu
目前还没有公认的方法来定义，更不用说量化运动稳定性了。在工程中，“轨道稳定性”是用Floquet乘法器定义的，该乘法器量化了纯周期系统从一个周期到下一个周期对扰动的离散响应。对于非周期系统，“局部稳定性”由局部散度指数定义，该指数量化了系统如何实时连续响应非常小的扰动。记录了10名年轻健康受试者在平地上和在电动跑步机上以相同速度步行10分钟时躯干三轴加速度和下肢矢状面关节角。在每个时间序列的每个百分比的步态周期（从0%到100%）计算最大Floquet乘数（Max FM），以量化这些运动的轨道稳定性。对不同行走条件下最大FM值的方差分析，以及最大FM值与先前公布的局部散度指数结果之间的相关性进行了计算。所有受试者都表现出轨道稳定的行走运动学（即最大FM值< 1.0），尽管这些相同的运动学先前被发现是局部不稳定的。在整个步态周期中，眼眶稳定性的变化通常很小，没有表现出系统的模式。在跑步机上行走对中外侧（p=0.040）和垂直（p=0.038）躯干加速度和踝关节运动学（p=0.002）的轨道稳定性有微小但有统计学意义的改善。然而，并非所有受试者都表现出这些改善
Currently there is no commonly accepted way to define, much less quantify, locomotor stability. In engineering, "orbital stability" is defined using Floquet multipliers that quantify how purely periodic systems respond to perturbations discretely from one cycle to the next. For aperiodic systems, "local stability" is defined by local divergence exponents that quantify how the system responds to very small perturbations continuously in real time. Triaxial trunk accelerations and lower extremity sagittal plane joint angles were recorded front ten young healthy subjects as they walked for 10 min over level ground and on a motorized treadmill at the same speed. Maximum Floquet multipliers (Max FM) were computed at each percent of the gait cycle (from 0% to 100%) for each time series to quantify the orbital stability of these movements. Analyses of variance comparing Max FM values between walking conditions and correlations between Max FM values and previously published local divergence exponent results were computed. All subjects exhibited orbitally stable walking kinematics (i.e., magnitudes of Max FM < 1.0), even though these same kinematics were previously found to be locally unstable. Variations in orbital stability across the gait cycle were generally small and exhibited no systematic patterns. Walking on the treadmill led to small, but statistically significant improvements in the orbital stability of mediolateral (p=0.040) and vertical (p=0.038) trunk accelerations and ankle joint kinematics (p=0.002). However these improvements were not exhibited by all subjects (p