Inter- and Intra-Rater Reliability of a Wearable Inertial Sensor for Spatiotemporal Gait Assessment in Stroke Survivors

Background and Objective: Stroke frequently impairs gait functionality, leading to significant limitations in functional independence and quality of life. Objective gait analysis is essential for evaluating clinical status and rehabilitation progress. While laboratory-bound, non-wearable systems are considered the gold standard, their high cost, complex infrastructure, and requirement for specialized personnel limit their routine implementation in daily clinical practice. Portable inertial measurement units have emerged as a practical, low-cost alternative for motion analysis outside traditional laboratory settings. However, evidence regarding specific commercial devices in pathological populations remains limited. This study aims to evaluate the inter-rater and intra-rater reliability of the commercially available Baiobit® lumbar-mounted inertial sensor for measuring spatiotemporal gait parameters in stroke survivors. Methodology: A prospective, single-group, repeated-measures design was conducted at a specialized neurorehabilitation clinic (Neuron Clinic, Madrid). A convenience sample of 22 adults diagnosed with subacute or chronic stroke who were able to ambulate independently was included. Gait assessments were performed by two trained evaluators across two separate sessions spaced 24 to 48 hours apart. During each session, the Baiobit® sensor was secured to the participants' sacral region (S1-S2) using an adjustable belt. Participants performed three 10-meter walking trials at their comfortable, self-selected pace for each evaluator. Reliability was quantified using Intraclass Correlation Coefficients (ICC), Standard Error of Measurement (SEM), and Minimal Detectable Change (MDC). Expected Outcomes: It is hypothesized that the Baiobit® inertial sensor will demonstrate adequate relative and absolute inter- and intra-rater reliability across spatiotemporal gait parameters, supporting its viability as an objective monitoring tool in routine stroke rehabilitation clinical settings.

Inclusion Criteria: * adults aged 18-85 years * confirmed diagnosis of stroke * ability to ambulate (FAC \> 4), regardless of foot-up use * Capacity to walk 10m without stopping and repeat the trials 6 times across the session * Cognitive ability to understand the study instruction and provide written informed consent Exclusion Criteria: * clinical instability or acute medical conditions that compromise gait safety * concomitant neurological conditions other than stroke * severe musculoskeletal disorders that interfere with gait analysis * balance or coordination impairments secondary to visual or auditory deficits * recent use of substances or medications that impair bait, balance, or postural control * pregnancy * cognitive or behavioral impairments that prevent the proper performance of the test