Data from: Reliability and minimum detectable change of temporal-spatial, kinematic, and dynamic stability measures during perturbed gait

Temporal-spatial, kinematic variability, and dynamic stability measures collected during perturbation-based assessment paradigms are often used to identify dysfunction associated with gait instability. However, it remains unclear which measures are most reliable for detecting and tracking responses to perturbations. This study systematically determined the between-session reliability and minimum detectable change values of temporal-spatial, kinematic variability, and dynamic stability measures during three types of perturbed gait. Twenty young healthy adults completed two identical testing sessions two weeks apart, comprised of an unperturbed and three perturbed (cognitive, physical, and visual) walking conditions in a virtual reality environment. Within each session, perturbation responses were compared to unperturbed walking using paired t-tests. Between-session reliability and minimum detectable change values were also calculated for each measure and condition. All temporal-spatial, kinematic variability and dynamic stability measures demonstrated fair to excellent between-session reliability. Minimal detectable change values, normalized to mean values ranged from 1–50%. Step width mean and variability measures demonstrated the greatest response to perturbations with excellent between-session reliability and low minimum detectable change values. Orbital stability measures demonstrated specificity to perturbation direction and sensitivity with excellent between-session reliability and low minimum detectable change values. We observed substantially greater between-session reliability and lower minimum detectable change values for local stability measures than previously described which may be the result of averaging across trials within a session and using velocity versus acceleration data for reconstruction of state spaces. Across all perturbation types, temporal-spatial, orbital and local measures were the most reliable measures with the lowest minimum detectable change values, supporting their use for tracking changes over multiple testing sessions. The between-session reliability and minimum detectable change values reported here provide an objective means for interpreting changes in temporal-spatial, kinematic variability, and dynamic stability measures during perturbed walking which may assist in identifying instability.

基于扰动的评估范式所采集的时空参数、运动学变异性（kinematic variability）及动态稳定性指标，常被用于识别与步态不稳相关的功能异常。然而，目前仍不清楚哪些指标在检测和追踪扰动响应方面表现最为可靠。本研究系统测定了三类扰动步态下，时空参数、运动学变异性及动态稳定性指标的测试间信度与最小可检测变化量（minimum detectable change, MDC）。20名年轻健康受试者完成了两次间隔两周的相同测试，测试包含虚拟现实环境下的无扰动行走及三类扰动行走（认知扰动、躯体扰动、视觉扰动）工况。在每次测试中，研究采用配对t检验，将扰动行走工况下的响应与无扰动行走进行对比。同时，研究还针对每项指标及每种工况计算了测试间信度与最小可检测变化量。所有时空参数、运动学变异性及动态稳定性指标均表现出尚可至极佳的测试间信度。归一化至均值后的最小可检测变化量范围为1%~50%。步宽均值与变异性指标对扰动的响应最为显著，且具备极佳的测试间信度与较低的最小可检测变化量。轨道稳定性指标对扰动方向具备特异性与敏感性，同时拥有极佳的测试间信度与较低的最小可检测变化量。相较于既往研究报道的结果，本研究中局部稳定性指标的测试间信度显著更高，最小可检测变化量则显著更低，这一现象可能源于对单次测试内多次试验数据取平均，以及采用速度而非加速度数据重构状态空间。在所有扰动工况下，时空参数、轨道稳定性及局部稳定性指标均为信度最高且最小可检测变化量最低的指标，这支持了它们可用于追踪多次测试间隔内的步态变化。本研究报道的测试间信度与最小可检测变化量，为解读扰动行走下时空参数、运动学变异性及动态稳定性指标的变化提供了客观依据，或可辅助步态不稳的识别工作。