Overground to omnidirectional: Spatiotemporal and muscle activation pattern adaptations across walking modalities, virtual reality, and pace constraints

The rapid expansion of virtual reality (VR) technology has led to the development of low-friction, slip-style omnidirectional treadmills (OTs), which have great promise for implementation into VR-based gait rehabilitation protocols. However, previous work indicates that use of these treadmills leads to unique gait patterns that may differ from overground gait, and there is a lack of research examining how OT gait differs from a conventional, belt-driven treadmill (CT). Thus, the purpose of this study was to characterize spatiotemporal and electromyographic gait patterns on an OT and to compare them with overground and CT walking. Fourteen healthy participants walked in these three conditions in both the real-world and in VR, as well as at fixed and preferred paces. Results indicate that use of the CT promoted significantly longer stride lengths (mean = 1.838 m) and reduced variability (coefficient of variation (CV) = 14.7%) compared to overground walking (mean = 1.578 m, CV = 21.4%). Moreover, the use of CT in VR at a fixed pace led to reduced biceps femoris (CV = 20.4%) and medial gastrocnemius (CV = 14.9%) variability compared to overground walking (biceps femoris CV = 26.4%, medial gastrocnemius CV = 22.2%), while use of the OT demonstrated variability similar to that of overground walking across measures. These results indicate that the user-driven aspect of OTs may elicit gait patterns more similar to overground walking than traditional belt-driven treadmills.