Development of a virtual reality-based intervention for community walking post stroke: an integrated knowledge translation approach.

PURPOSE: To develop a virtual reality (VR) based intervention targeting community walking requirements. METHODS: Two focus groups each involving 7 clinicians allowed exploring optimal features, needed support and perceived favorable/unfavorable factors associated with the use of the VR-based intervention from the clinicians' perspective. Three stroke survivors and 2 clinicians further interacted with the intervention and filled questionnaires related to acceptability and favorable/unfavorable perceptions on the VR intervention. Stroke participants additionally rated their perceived effort (NASA Tax Load Index), presence (Slater-Usoh-Steed) and cybersickness (Simulator Sickness Questionnaire). RESULTS: Results identified optimal features (patient eligibility criteria, task complexity), needed support (training, human assistance), as well as favorable (cognitive stimulation, engagement, representativeness of therapeutic goals) and unfavorable factors (misalignment with a natural walking pattern, client suitability, generalization to real-life) associated with the intervention. Acceptability scores following the interaction with the tool were 28 and 42 (max 56) for clinicians and ranged from 43 to 52 for stroke participants. Stroke participants reported moderate perceptions of effort (range:20-33/max:60), high levels of presence (29-42/42) and minimal cybersickness (0-3/64). CONCLUSION: Findings collected in the early development phase of the VR intervention will allow addressing favorable/unfavorable factors and incorporating desired optimal features, prior to conducting effectiveness and implementation studies.

This study presents the development process of a new virtual reality (VR) intervention for community walking and participation in stroke survivors.Results from the focus group and hands-on pilot trial suggest that the VR intervention is feasible and accepted by clinicians and stroke survivors.Addressing favorable/unfavorable factors and incorporating features desired by clinicians in the development of the VR tool should promote its eventual implementation in clinical setting.

Impact of dual tasking on gaze behaviour and locomotor strategies adopted while circumventing virtual pedestrians during a collision avoidance task.

We investigated gaze behaviour and collision avoidance strategies in 16 healthy young individuals walking towards a goal while exposed to virtual pedestrians (VRPs) approaching from different directions (left, middle, right). This locomotor task and an auditory-based cognitive task were performed under single and dual-task conditions. Longer gaze fixation durations were observed on the approaching vs. other VRPs, with longer fixations devoted to the upper trunk and head compared to other body segments. Compared to other pedestrian approaches, the middle pedestrian received longer fixations and elicited faster walking speeds, larger onset distances of trajectory devitation and smaller obstacle clearances. Gaze and locomotor behaviours were similar between single and dual-task conditions but dual-task costs were observed for the cognitive task. The longer gaze fixations on approaching vs. other pedestrians suggest that enhanced visual attention is devoted to pedestrians posing a greater risk of collision. Likewise, longer gaze fixations for the middle pedestrians may be due to the greater collision risk entailed by this condition, and/or to the fact that this pedestrian was positioned in front of the end goal. Longer fixations on approaching VRPs' trunk and head may serve the purpose of anticipating their walking trajectory. Finally, the dual-task effects that were limited to the cognitive task suggest that healthy young adults prioritize the locomotor task and associated acquisition of visual information. The healthy patterns of visuomotor behaviour characterized in this study will serve as a basis for comparison to further understand defective collision avoidance strategies in patient populations.

Coordinating Clearance and Postural Reorientation When Avoiding Physical and Virtual Pedestrians.

Community ambulation requires efficient locomotor adaptations to avoid collisions with other pedestrians. Virtual reality (VR) offers the possibility to experimentally manipulate the environment, allowing researchers to safely assess locomotor responses during pedestrian interactions. In this paper, locomotor adjustments in response to interferers approaching from different directions were examined in both a physical and a virtual environment. Further analysis compared the extent to which locomotor adjustments were influenced by different circumvention strategies. To achieve these goals, twelve healthy young participants were assessed while walking towards a target and avoiding pedestrians approaching from the left, middle, or right, in both VR and the real world. Results showed that in VR, participants walked with slower velocities, maintained larger minimum distances, and reached larger trajectory deviations. Additionally, trajectory deviations and postural reorientations were executed earlier in VR. There were additional differences according to whether participants had to give way to a head-on approaching interferer or choose to pass in front or behind a diagonally approaching interferer. Compared to the other circumvention strategies, passing in front was associated with faster walking speeds as well as smaller and later trajectory deviations and postural reorientations. Lastly, while a cephalocaudal sequence of segment reorientation was observed in both environments, no difference between the onset of head and thorax reorientation was observed in VR. In conclusion, obstacle clearance and postural reorientation are modulated by the environment and circumvention strategies. These modulations should be considered when designing experiments or clinical interventions.

Locomotor circumvention strategies in response to static pedestrians in a virtual and physical environment.

BACKGROUND: Circumvention of pedestrians is an essential requirement of community ambulation and can be challenging to reproduce in laboratory or clinical settings. Virtual reality (VR) is a powerful tool that allows investigations, assessments or training of such tasks under ecological but controlled conditions. The extent to which current VR technologies can elicit responses similar to those observed in the physical world, however, remains to be determined. RESEARCH QUESTIONS: (1) To what extent does the circumvention of static pedestrians in VR differ from that observed in the physical environment (PE)? and; (2) To what extent does the inter-trial variability of obstacle circumvention outcomes differ in VR vs. the PE? METHODS: Healthy young participants (n = 13) were assessed while walking and avoiding a collision with an interferer that stood either at 3.0 and 3.5 m from the participant's starting position (experimental trials) or that exited to the side (catch trials). The task was performed in the PE and VE, in a random order. A female collaborator acted as interferer in the PE and her kinematics was used to create the avatar used in the VE. RESULTS: Compared to the PE, the circumvention of a static pedestrian in VR was characterized by larger obstacle clearances and slower walking speeds. Characteristics of circumvention strategy such as the preferred side of circumvention, response to obstacle position and pattern of speed adaptation were similar between VR and the PE. Inter-trial variability for the different outcomes were also similar between the two environments. SIGNIFICANCE: Differences in obstacle clearance and speed indicate the use of "safer" circumvention strategies in VR. However, the patterns of locomotor adaptation that were largely similar between the two environments which suggests that VR is a valuable tool to study, assess and possibly train complex locomotor tasks such as obstacle avoidance.

Circumvention of Pedestrians While Walking in Virtual and Physical Environments.

Virtual environments (VEs) are increasingly used in the context of scientific inquiries and rehabilitation for tasks that are otherwise difficult to control or perform safely in physical environments (PEs), such as avoiding other pedestrians during locomotion. The usefulness of VEs, however, remains constrained by the extent to which they can elicit natural responses. The objectives of the study were to examine circumvention strategies in response to pedestrians approaching from different directions in the VE versus PE and to determine the effects of repeated practice on the circumvention strategies. Twelve participants were assessed over five blocks of eight trials that consisted of walking toward a target while circumventing pedestrians approaching from different directions (0°, ± 30° right or left or none) in the VE and the PE. Similar onset distances of circumvention strategy and preferred side of circumvention were observed between the two environments. Participants, however, maintained enlarged minimum distances from the interferer (13%) and walked slower (11.5%) in the VE. Repeated practice resulted in walking speed increments of 7.4% over the entire session that were similar in the VE versus PE. While the changes observed in VE may reflect the use of more cautious circumvention strategies, the similarities in strategies between the two environments and the advantages of VEs (e.g., controlled exposure, reproduction of ecologically valid conditions, and safety) suggest that virtual reality is a valuable tool to study visually guided locomotor tasks, such as pedestrian circumvention, and shows great potential for assessment and intervention in physical rehabilitation.