Comparison of lower limb joint moment and power during turning gait between young and old adults using hierarchical Bayesian inference

Age-related differences in lower limb joint moment (JM), and joint power (JP) during turning remain unclear. The present study investigated age-related differences in lower limb JM and JP during turning between young adults (YAs) and old adults (OAs). We introduced the hierarchical Bayesian inference for comparing and identifying differences in JM, angular velocity(ω), and JP at each stance phase in the two age groups. This study included 16 healthy YAs and 16 healthy OAs (8 men and 8 women in each group). Participants performed 90° step turns to the right at a self-selected natural speed. On comparing the age groups, during 90° step turning, the OA group exhibited larger extention hip JM and JP to control (brake) the upper body in the sagittal plane, exhibited larger abductor moment in each lower limb joint for preventing the body from leaning in the frontal plane during the mid-stance phase, and exhibited larger hip JP and ω and smaller ankle JM in the transverse plane to rotate the body during the mid-stance phase. Our findings suggested that the overall reliance on the hip joint to control body motion in each anatomical plane during step turning is higher in the OA group than in the YA group. In addition, the hierarchical Bayesian inference is useful for comparing the time courses of JM, ω, and JP.