Falls during walking are a leading cause of injuries across aging. Many of these falls are due to slips and trips. The ability to perceive disturbances to ongoing motion may play an important role in the control of walking balance. However, disturbance perception has been investigated in standing balance, but its role in walking balance due to slip- and trip-like disturbances remains largely unknown. Characterizing locomotor disturbance perception in young adults may lead to a more comprehensive understanding of sensorimotor walking balance control.

This work defined locomotor disturbance perception in response to slip and trip-like disturbances in young adults. We demonstrate that young adults can perceive small locomotor disturbances. Since we found that young adults had an ability to perceive small slip and trip-like locomotor disturbances, we investigated the role of whole-body and local sensory feedback in perceiving these disturbances. We identified significantly increased deviations for perceived perturbations in sagittalplane & frontal-plane whole-body angular momentum (WBAM), anteroposterior center of mass (CoM) position and velocity, and mediolateral CoM position, velocity, and acceleration. Because whole-body motion is not sensed directly but arises from integrating various sensory feedback signals, we also explored local sensory feedback contributions to the perception of locomotor disturbances. We used novel kinematic analogues to estimate the local sensory feedback contributions. We found that our novel kinematic analogues for ankle and knee proprioception play a role in perceiving these disturbances in young adults. Based largely on these findings, we investigated the role of medial gastrocnemius muscle length changes play in perceiving locomotor disturbances. For trip-like disturbances, we identified significantly increased average and peak deviations in Achilles tendon and musculotendon unit length for perceived versus not perceived trials. However, there was no effect on the timing of the peak deviation. For sliplike disturbances, there was no significant effect for average deviation, peak deviation, or timing of the peak deviation for all musculotendon complex lengths between perceived versus not perceived disturbances. These results suggest that either tendon force or overall musculotendon unit length monitoring plays a role in perceiving locomotor disturbances. Since disturbance perception has been characterized and the role sensory feedback plays in disturbance perception for young adults, it should be evaluated in balance-impaired populations to determine shifts in sensorimotor control and the role it plays in fall risk.