Discrepancies in Walking Speed Measurements Post-Bed-Rest: A Comparative Analysis of Real-World vs. Laboratory Assessments

Abstract Understanding differences between real-world walking speed (RWS) and laboratory-measured walking speed (LWS) is crucial for comprehensive mobility assessments, especially in context of prolonged immobilization. This study aimed to investigate disparities in walking speed following a 60-day bed-rest period. In eleven male subjects, RWS was continuously monitored using a tri-axial accelerometer worn on the waist, while LWS was assessed via a 10-meter walk test at preferred speed, on three different study days after immobilization. Statistical analyses included Bland-Altman and Pearson's correlation to evaluate agreement between RWS and LWS, alongside paired-sample t-tests and univariate linear regression models to assess significance of differences and temporal effects on gait speed. Results of Bland-Altman analysis showed no agreement between RWS and LWS (mean difference 0.77 m/s) and nonsignificant correlation (r = 0.19, p-value = 0.3). Paired-sample t-tests indicated significantly lower RWS compared to LWS for all study days (p-value < 0.001). Univariate linear regression models demonstrated a significant effect of test day on RWS (p-value < 0.001) but not on LWS (p-value = 0.23). These findings emphasize the importance of integrating both assessments to capture comprehensive mobility changes following prolonged periods of inactivity. Particularly significant is that RWS is constantly lower than LWS, with the former being more representative as it reflects what normally participants would do when not under observation. Lastly, understanding discrepancies between RWS and LWS would allow for more appropriate rehabilitation programs to speed up recovery while simultaneously keeping the rehabilitation safe and tailored.