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(perturbation-based assessment paradigms)中采集的时空参数、运动学变异性与动态稳定性指标(temporal-spatial, kinematic variability, and dynamic stability measures)，常被用于识别与步态不稳(gait instability)相关的功能异常。然而，目前仍不明确哪些指标在检测、追踪扰动响应时最为可靠。本研究系统测定了三种扰动步态(perturbed gait)下，上述指标的会话间信度(between-session reliability)与最小可检测变化量(minimum detectable change)。20名健康青年成年人间隔两周完成两次相同测试会话，每次测试均包含虚拟现实(virtual reality)环境下的无扰动行走与三种扰动（认知、躯体、视觉）行走工况。在每次会话中，研究采用配对t检验(paired t-tests)，将扰动行走的响应与无扰动行走进行对比。研究还计算了各指标与各工况下的会话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会话间信度。以均值归一化后的最小可检测变化量范围为1%~50%。步幅均值与变异性指标对扰动的响应最为显著，且具备极佳的会话间信度与较低的最小可检测变化量。轨道式稳定性指标(orbital stability measures)对扰动方向具有特异性与敏感度，同样具备极佳的会话间信度与较低的最小可检测变化量。相较于既往研究结果，我们发现局部稳定性指标(local stability measures)的会话间信度显著更高，最小可检测变化量则更低，这可能得益于对单次会话内多次试验结果取平均，以及采用速度而非加速度数据进行状态空间(state spaces)重构。在所有扰动类型中，时空参数、轨道式稳定性指标与局部稳定性指标的信度最高，且最小可检测变化量最低，这支持其可用于追踪多次测试会话中的变化情况。本研究报道的会话间信度与最小可检测变化量，为解读扰动行走时空参数、运动学变异性及动态稳定性指标的变化提供了客观依据，或可辅助识别步态不稳情况。