Effects of Task-Driven Head Orientations on Gait and Balance During Walking in Virtual Reality.

During everyday walking, secondary tasks such as looking at a phone or reading billboards on the streets often require deliberate head reorientation and attention allocation. However, the effect of these concurrent head-orientation demands on gait regulation and secondary task performance has not been systematically quantified. We addressed this gap using an immersive virtual reality (VR) framework in overground walking with distinct head-orientation tasks. Thirteen healthy adults performed overground walking in a one-to-one, scale-matched virtual replica of the laboratory while simultaneously performing head-orientation tasks presented in VR using a head-mounted display. Participants performed five motor-vestibular (MV) tasks involving tracking a visual target, i.e., a ball, positioned egocentrically relative to the body (Neutral, Flexion, Extension, and Rotation tasks) or allocentrically fixed to the virtual room. Participants also performed three motor-vestibular-cognitive (MVC) tasks that combined head-orientation with concurrent cognitive demands: Stroop test, Arithmetic task, and Trail Making Test. Among MV tasks, orientation of the head in Extension, Rotation, and Allocentric tasks reduced gait speed, step length, and forward margin of stability while increasing motor dual-task cost compared with orientation of the head in Neutral and Flexion tasks. MVC tasks further elevated motor dual-task cost compared to MV tasks. While gait adaptations across the MVC tasks were similar, the Trail Making Test had a significantly higher cognitive dual-task cost. This study provides a novel VR paradigm for quantifying gait and dual-task costs under head-orientation constraints, with implications for developing more sensitive gait assessments and dual-task training in those with motor and/or cognitive impairments.