Walking synchronized to external cues is a common practice in clinical settings. Several research studies showed that this popular gait rehabilitation tool alters gait variability. There is also recent evidence which suggests that alterations in the temporal structure of the external cues could restore gait variability at healthy levels. It is unknown, however, if such alterations produce similar effects if the cueing modalities used are different; visual or auditory. The modality could affect gait variability differentially, since there is evidence that auditory cues mostly act in the temporal domain of gait, while visual cues act in the spatial domain of gait. This study investigated how synchronizing steps with visual and auditory cues that are presented with different temporal structures could affect gait variability during treadmill walking. Three different temporal structured stimuli were used, invariant, fractal and random, in both modalities. Stride times, length and speed were determined, and their fractal scaling (an indicator of complexity) and coefficient of variation (CV) were calculated. No differences were observed in the CV, regardless of the cueing modality and the temporal structure of the stimuli. In terms of the stride time's fractal scaling, we observed that the fractal stimulus induced higher values compared to random and invariant stimuli. The same was also observed in stride length, but only for the visual cueing modality. No differences were observed for stride speed. The selection of the cueing modality seems to be an important feature of gait rehabilitation. Visual cues are possibly a better choice due to the dependency on vision during walking. This is particularly evident during treadmill walking, a common practice in a clinical setting. Because of the treadmill effect on the temporal domain of gait, the use of auditory cues can be minimal, compared to visual cues.

Introduction: Perception of self-motion through virtual reality (VR) provides a unique avenue to improve gait adaptation in chronic stroke survivors. In this ongoing study, stroke survivors adapted to a split-belt paradigm and perception of self-motion was provided in a VR environment. It was hypothesized that the relationship between baseline spatio-temporal asymmetry and gait adaptation would be different in VR than Non-VR (control) groups. Methods: Chronic stroke survivors (n=24; age=59.5±13.68years) participated in a split-belt adaptation paradigm and were randomly put into a VR or a Non-VR group. The recruited subjects included a wide range in lower limb Fugl-Meyer scores (11-46) and baseline gait asymmetries (spatial: -17% to +44%, temporal: -16% to +39%). The adaptation trials exposed the participants to different belt speeds for each leg. In addition, pre- and post-adaptation treadmill trials were performed at the participants’ preferred walking speed. The VR stimuli consisted of walking in an infinitely long virtual corridor. Spatiotemporal measures (step length and step time asymmetries) as correlates of adaptation were compared with baseline asymmetries using Pearson correlation coefficients. Results: Step length asymmetry during adaptation showed a significant relationship with baseline asymmetry only for the VR (r=0.722, p=0.012) but not the Non-VR group (r=-0.457, p=0.116). During transfer, a significant relationship was shown for both VR (r=0.752, p=0.008) and Non-VR (r=-0.616, p=0.025) groups. However, this relationship was positive for VR and negative for Non-VR. Step time asymmetry during adaptation showed a borderline relationship with baseline asymmetry only for the VR (r=0.569, p=0.068) but not the non-VR group (r=-0.014, p=0.964). During transfer, a significant relationship was shown only for the VR (r=0.614, p=0.045) but not the non-VR (r=-0.366, p=0.218) group. Discussion: The results indicated a potentially greater impact of VR in stroke survivors with high levels of spatial and/temporal gait asymmetries. Future studies will investigate the magnitude and mechanisms of this impact. This will help VR-based gait rehabilitation to be stratified and streamlined for greater benefit.

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