Estimating and interpreting how humans prioritize multiple movement goals during walking.

BACKGROUND: Walking requires managing competing movement goals shaped by the demands of everyday activity. Several important goals during overground walking include maintaining a desired walking speed, achieving an intended foot placement, preserving postural and locomotor balance, and reducing energy expenditure. Biomechanical simulation and motor control-based methods use goal-related cost functions or structured models to identify people’s movement priorities but are often restricted to simple movement scenarios and are currently impractical for broad deployment. METHODS: Here, we systematically vary four movement goals during an overground walking experiment, characterize the resulting trade-offs in spatiotemporal gait metrics, and show that these trade-offs are sufficient to estimate participants’ perceived ranking of movement goals. RESULTS: Gait metrics across participants became more heterogenous as combinations of movement goal prompts became more complex, suggesting person-specific movement strategies. Participants’ perceived prioritization of movement goals showed systematic associations with corresponding gait metrics, with the strongest relationships observed for visually guided goals such as balance and foot placement. Subject-agnostic regression models estimated the perceived order of importance of movement goals with 21% error, and subject-specific models reduced this error to 11%. CONCLUSIONS: This work establishes an approach for estimation of movement priorities in young, healthy adults using simple gait metrics and provides a framework that could inform future studies beyond the laboratory.