Differences between local and orbital dynamic stability during human walking.
Differences between local and orbital dynamic stability during human walking.
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人类行走时局部和轨道动态稳定性之间的差异。
DOI：
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
H. G. Kang
中科院分区：
文献类型：
--
作者：
J. Dingwell;H. G. Kang
目前还没有被普遍接受的方法来定义运动稳定性，更不用说量化了。在工程上，“轨道稳定性”的定义是使用弗洛奎乘数，它量化纯周期系统如何从一个周期到下一个周期离散地对扰动做出反应。对于非周期系统，“局部稳定性”是由局部发散指数来定义的，这些发散指数量化了系统如何实时连续地响应非常小的扰动。记录了10名健康青年在平地上行走10min和在等速机动跑步机上行走10min时的躯干三轴加速度和小腿矢状面关节角度。在步态周期的每个百分比(从0%到100%)计算每个时间序列的最大Floquet乘数(Max Fm)，以量化这些运动的轨道稳定性。计算比较行走状态的最大FM值和最大FM值与先前发表的局部发散指数结果之间的相关性的方差分析。所有受试者都表现出轨道稳定的行走运动学(即，最大Fm和lt；1.0的大小)，即使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，轨道稳定性的变化通常很小，并且没有表现出系统性的模式。在跑步机上行走对内侧(p=0.040)和垂直(p=0.038)躯干加速和踝关节运动学(p=0.002)的眼眶稳定性有微小但有统计学意义的改善。然而，并不是所有的受试者都表现出这些改善(对于受试者x条件交互效应，P<；OR=0.012)。最大FM值和以前发表的局部发散指数之间的相关性不一致，12个比较中有11个没有统计学意义(R2<；or=19.8%；p>；or=0.049)。因此，人类行走固有的变异性表现为局部不稳定，并不会对行走的轨道稳定性产生实质性的不利影响。这项研究的结果将使今后的努力能够更好地了解保持轨道稳定的局部不稳定运动和导致全球不稳定(即下降)的运动之间的界限。
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 from 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 < or = 0.012 for subject x condition interaction effects). Correlations between Max FM values and previously published local divergence exponents were inconsistent and 11 of the 12 comparisons made were not statistically significant (r2 < or = 19.8%; p > or = 0.049). Thus, the variability inherent in human walking, which manifests itself as local instability, does not substantially adversely affect the orbital stability of walking. The results of this study will allow future efforts to gain a better understanding of where the boundaries lie between locally unstable movements that remain orbitally stable and those that lead to global instability (i.e., falling).
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影响因子：
2.4
作者：
Donelan, JM;Shipman, DW;Kuo, AD
通讯作者：
Kuo, AD
DOI：
10.1115/1.1835358
发表时间：
2005-02
期刊：
Journal of biomechanical engineering
影响因子：
--
作者：
Shawn Russell;K. Granata;P. Sheth
通讯作者：
Shawn Russell;K. Granata;P. Sheth
影响因子：
4.3
作者：
Hausdorff, JM;Rios, DA;Edelberg, HK
通讯作者：
Edelberg, HK
影响因子：
3.3
作者：
HAUSDORFF, JM;PENG, CK;GOLDBERGER, AL
通讯作者：
GOLDBERGER, AL