Department of Orthopedics and Sports Medicine, Medstar Health Research Institute, Baltimore, MD, United States.
Department of Electrical and Computer Engineering, University of Alabama, Tuscaloosa, United States.
Gait Posture. 2024 Sep;113:504-511. doi: 10.1016/j.gaitpost.2024.08.007. Epub 2024 Aug 21.
Changes in spatio-temporal gait parameters and their variability during balance-challenging tasks are markers of motor performance linked to fall risk. Radio frequency (RF) sensors hold great promise towards achieving continuous remote monitoring of these parameters.
To establish the concurrent validity of RF-based gait metrics extracted using micro-Doppler (µD) signatures and to determine whether these metrics are sensitive to gait modifications created by multidirectional visual perturbations.
Fifteen participants walked overground in a virtual environment (VE) and VE with medio-lateral (ML) and antero-posterior (AP) perturbations. An optoelectronic motion capture system and one RF sensor were used to extract the linear velocity of the trunk and estimate step time (ST), step velocity (SV), step length (SL), and their variability (STV, SVV, and SLV). Intra-class coefficient for consistency (ICC), mean and standard deviation of the differences (MD), 95 % limits of agreement, and Pearson correlation coefficients (r) were used to determine concurrent validity. One-way repeated-measures analysis of variance was used to analyze the main and interaction effects of visual conditions.
All outcomes showed good to excellent reliability (r>0.795, ICC>0.886). Average gait parameters showed good to excellent agreement, with values obtained with the RF sensor systematically smaller than the values obtained with the markers (MD of 0.001 s, 0.09 m/s, and 0.06 m). Gait variability parameters showed poor to moderate agreement, with values obtained with the RF sensor systematically larger than those obtained with the markers (MD of 1.9 %-3.9 %). Both measurement systems reported decreased SL and SV during ML perturbations, but the gait variability parameters extracted with the radar were not able to detect the higher STV and SLV during this condition.
The radar µD signature is a valid and reliable method for the assessment of average spatio-temporal gait parameters but gait variability measures need to be viewed with caution because of the lower levels of agreement and sensitivity to ML visual perturbations. This work represents an initial investigation for the development of a low-cost system that will facilitate aging-in-place by providing remote monitoring of gait in natural settings.
时空步态参数的变化及其在平衡挑战任务中的可变性是与跌倒风险相关的运动表现的标志物。射频 (RF) 传感器在实现这些参数的连续远程监测方面具有巨大的潜力。
确定基于微多普勒 (µD) 特征提取的 RF 步态指标的同时效度，并确定这些指标是否对多方向视觉干扰引起的步态变化敏感。
15 名参与者在虚拟环境 (VE) 和具有左右 (ML) 和前后 (AP) 干扰的 VE 中进行地面行走。使用光电运动捕捉系统和一个 RF 传感器来提取躯干的线性速度，并估计步时 (ST)、步速 (SV)、步长 (SL) 及其变异性 (STV、SVV 和 SLV)。使用组内一致性系数 (ICC)、差异的均值和标准差 (MD)、95%一致性界限和 Pearson 相关系数 (r) 来确定同时效度。采用单向重复测量方差分析来分析视觉条件的主要和交互效应。
所有结果均显示出良好到极好的可靠性 (r>0.795，ICC>0.886)。平均步态参数显示出良好到极好的一致性，RF 传感器获得的值比标记器获得的值系统地小 (MD 为 0.001s、0.09m/s 和 0.06m)。步态变异性参数显示出较差到中等的一致性，RF 传感器获得的值比标记器获得的值系统地大 (MD 为 1.9%-3.9%)。两种测量系统都报告说，在 ML 干扰期间 SL 和 SV 减小，但雷达提取的步态变异性参数无法检测到这种情况下更高的 STV 和 SLV。
雷达 µD 特征是评估平均时空步态参数的有效且可靠的方法，但步态变异性测量值需要谨慎看待，因为其一致性和对 ML 视觉干扰的敏感性较低。这项工作代表了开发低成本系统的初步研究，该系统将通过在自然环境中提供步态的远程监测，促进老年人在家中生活。
