Concurrent validity of connected insoles to quantify temporal parameters of single-step initiation in healthy young adults

Gait or single-step initiation is classically measured in specialized laboratory by using at least one gold standard device: a force-plate. With the emergence of wearable sensors for measuring posture-movement parameters in more ecological situations, studies have been conducted to validate inertial measurement units as reliable tools for measuring temporal parameters of movement. Whereas connected insoles appear to be a more straightforward device than inertial units for detecting phases of movement, no validation studies have yet been conducted with such tools to measure movement initiation. From a standing position on a force-plate and equipped with a pair of connected insoles, 14 healthy young adults initiated several single-steps in various speed conditions. An algorithm was created to detect movement events and study the duration of three movement phases: anticipatory postural adjustments, execution and total single-step initiation phases. The comparisons between the reference and the wearable devices were performed using Concordance Correlation Coefficient (CCC) and Bland-Altman plots. The CCC was above the acceptability threshold of 0.68 for all the phases (mean = 0.81, range [0.71-0.89]). In addition, the differences between both devices depend only marginally on speed instruction. These results demonstrated that, associated to the algorithm we created, connected insoles is a reliable device to measure the duration of the phases of the single-step initiation in healthy young adults. Moreover, the marginal impact of movement speed suggests that this tool might also be valid for population with low gait speed, such as the elderly and patients with neurological disorders.