Thigh-Worn Sensor for Measuring Initial and Final Contact During Gait in a Mobility Impaired Population: Validation Study
Background: Measuring free-living gait with wearable sensors has great potential in supporting personalised rehabilitation. There are challenges meeting the accuracy levels of laboratory-based measurements in detecting initial and final contact, particularly in impaired populations. Objective: To test the criterion validity of a novel temporal gait measurement technique, combining the ActivPAL 4+ (PAL Technologies, Glasgow, UK) and the Teager-Kaiser Energy Operator, to measure stance phase duration in chronic stroke survivors through comparison with the Evoke cluster marker system (Vicon, Oxford, UK). Methods: Stroke participants (n=13, mean age = 59 years 14, time since stroke = 1.5 years 0.5) were assessed using the ACTIVPAL 4+ and a motion capture system. Two 10m walk tests were measured, while wearing two ActivPAL 4+ (located on anterior of both thighs) and clusters on the pelvis and ankles from the motion capture system. The Teager-Kaiser Energy Operator signal processing technique was used to extract the stance durations of the ActivPAL 4+, compared with a previously validated method. Results: There was a good agreement (bias: 0.03s, limits of agreement: -0.22 to 0.28s) between the ACTIVPAL 4+ and motion capture system despite a slight underestimation (mean stance time: 0.850s vs. motion capture system: 0.881s). Conclusions: Findings suggest the ACTIVPAL 4+, combined with Teager-Kaiser Energy Operator technique, provides valid stance time measurements when compared laboratory-based systems, supporting its use in free-living gait analysis and feedback during rehabilitation. Limitations include laboratory-only validation and a small population of chronic stroke patients. Future work should explore free-living gait, and larger, and broader, cross section of stroke populations.
