Variability in kinematic coupling assessed by vector coding and continuous relative phase
Variability in kinematic coupling assessed by vector coding and continuous relative phase
复制标题
DOI：
10.1016/j.jbiomech.2010.05.014
复制
发表时间：
2010-09-17
影响因子：
2.4
通讯作者：
Hamill, Joseph
中科院分区：
文献类型：
--
作者：
Miller, Ross H.;Chang, Ryan;Hamill, Joseph
人体运动运动学时空协调的可变性通常通过矢量编码和连续相对相位（CRP）来评估。为了便于对使用不同技术评估变异性的研究结果进行适当的比较，本研究的目的是：(1)确定矢量编码和CRP的行为是否符合关于变异性和状态空间转换的动力系统理论；(2)确定在使用矢量编码或CRP时，运动过程中协调变化的趋势是否一致。我们提出了一个理论案例（洛伦兹吸引子）和两个实验案例（22名受试者在地上行走时后脚-前脚耦合；跑步机速度对5名受试者大腿-腿耦合的影响）。在理论情况下，CRP量化的可变性比矢量编码量化的可变性更符合动力系统理论的状态空间跃迁。在实验案例中，这种区别不太清楚，尽管CRP似乎是一个更保守的可变性指标。在地面行走的站立阶段，变异峰的幅度（均p < 0.001）和时间（均p < 0.04）取决于是否使用矢量编码或CRP进行两次耦合。在跑步机运动的跨步周期中也观察到类似的差异（所有效应值均为> 2.8）。然而，两种方法在步幅周期中，随着速度的增加，平均变异性的变化是一致的（所有效应值都< 0.2）。结果表明，使用CRP量化变异的研究结果与使用矢量编码的研究结果之间的比较应谨慎进行。(C) 2010 Elsevier Ltd.版权所有。
Variability in the spatio-temporal coordination of human movement kinematics is often assessed by vector coding and continuous relative phase (CRP). To facilitate appropriate comparisons between the findings of studies that have used different techniques to assess variability, the purposes of this study were: (1) to determine if both vector coding and CRP behave according to dynamical systems theories on variability and state space transitions; and (2) to determine if trends in coordination variability during movement are consistent when using either vector coding or CRP. We present both a theoretical case (the Lorenz Attractor) and two experimental cases (rearfoot-forefoot coupling during overground walking for 22 subjects; the effect of treadmill speed on thigh-leg coupling for five subjects). In the theoretical case, variability quantified by CRP agreed with dynamical systems theory on state space transitions more so than variability quantified by vector coding. In experimental cases, this distinction was less clear, although CRP appeared to be a more conservative metric for variability. The magnitudes (all p < 0.001) and timings (all p < 0.04) of peaks in variability during the stance phase of overground walking depended on whether vector coding or CRP was used for two couplings. Similar distinctions were observed for peaks during the stride cycle of treadmill locomotion (all effect sizes > 2.8). However, changes in the average variability during the stride cycle as speed increased were consistent for both methods (all effect sizes < 0.2). The results suggest that comparisons between the findings of studies that have quantified variability using CRP and those that have used vector coding should be made with caution. (C) 2010 Elsevier Ltd. All rights reserved.