Gait coordination in overground walking with a virtual reality avatar

Little information is currently available on interpersonal gait synchronisation in overground walking. This is caused by difficulties in continuous gait monitoring over many steps while ensuring repeatability of experimental conditions. These challenges could be overcome by utilising immersive virtual reality (VR), assuming it offers ecological validity. To this end, this study provides some of the first evidence of gait coordination patterns for overground walking dyads in VR. Six subjects covered the total distance of 27 km while walking with a pacer. The pacer was either a real human subject or their anatomically and biomechanically representative VR avatar driven by an artificial intelligence algorithm. Side-by-side and front-to-back arrangements were tested without and with the instruction to synchronise steps. Little evidence of spontaneous gait coordination was found in both visual conditions, but persistent gait coordination patterns were found in the case of intentional synchronisation. Front-to-back rather than side-by-side arrangement consistently yielded in the latter case higher mean synchronisation strength index. Although the mean magnitude of synchronisation strength index was overall comparable in both visual conditions when walking under the instruction to synchronise steps, quantitative and qualitative differences were found which might be associated with common limitations of VR solutions.