Manipulability Analysis of Anterior and Mediolateral Dynamic Gait Stability of Young and Elderly Individuals

Humans maintain postural stability while walking by modulating their spatiotemporal walking features. It is crucial for humans to be able to restore stability in the event of a transient loss. However, the ease of adjusting postural stability has not yet been investigated extensively. This study applied manipulability, a concept widely used in robotics, to analyze the margin of stability (MoS), a measure of dynamic postural stability. The MoS values along each of the anterior and mediolateral directions were modeled as a function of spatiotemporal gait parameters, and the manipulability of the MoS was computed. We observed differences in manipulability between two age groups (60 healthy elderly adults and 60 healthy young individuals in their 20s) from an open database. The manipulability of the elderly was significantly higher than that of the young, suggesting that the elderly employed walking postures that allowed them to adjust their stability with relative ease. Furthermore, for the young group, the manipulability tended to be low when the mediolateral stability was low, with a correlation coefficient of 0.67. In contrast, the elderly group did not exhibit this relationship, showing differences in walking strategies between young and elderly individuals. The manipulability analysis of dynamic gait stability provides insights into revealing human gait strategies.