• Change in Pittsburgh Rehabilitation Participation Scale (PRPS) Score [ Time Frame: Day 1, after each of the three biofeedback interface sessions ]
  The PRPS is a single-item, clinician-rated instrument assessing the participant's engagement during each biofeedback bout. The level of participation is scored on a scale from 1 (none) to 6 (excellent), with higher values indicating greater participation in the therapy session.
• Change in Boredom [ Time Frame: Day 1, after each of the three biofeedback interface sessions ]
  Boredom will be assessed by 10-point visual analog scale asking participants to rate how bored they felt during the walk, where 1 is not bored and 10 is very bored.
• Success rate of target paretic AGRF [ Time Frame: Day 1, after each of the three biofeedback interface sessions ]
  The success rate of the targeted training task will be assessed as the percentage of steps for which the target paretic AGRF was achieved.

• Change in Fatigue [ Time Frame: Day 1, after each of the three biofeedback interface sessions ]
  Fatigue will be assessed by 10-point visual analog scale asking participants to rate how tired they felt during the walk, where 1 is not fatigued and 10 is very fatigued.
• Change in Hopkins Rehabilitation Engagement Rating Scale (HRERS) Score [ Time Frame: Day 1, after each of the three biofeedback interface sessions ]
  The HRERS will be used to assess participant engagement during each biofeedback bout. The HRERS is a 5-item instrument where clinicians indicate how engaged the participant was during a rehabilitation session on a 6- point scale ranging from 1 (never) to 6 (always). Total scores range from 5 to 30 with higher scores indicating increased engagement.
• Change in Motivation [ Time Frame: Day 1, after each of the three biofeedback interface sessions ]
  Motivation will be assessed by 10-point visual analog scale asking participants to rate how motivated they felt during the walk, where 1 is not motivated and 10 is very motivated.
• Game Ease of Use [ Time Frame: Day 1 ]
  User experience of the biofeedback game will be assessed with a 10-point scale asking participants to rate the ease of use, where 1 is very difficult to use and 10 is very easy to use. Participants will also be asked an open-ended survey question requesting comments and feedback about game's features (e.g. "In your opinion, what were the good and bad things about the game's ease of use"?).

This study will conduct a preliminary evaluation of and obtain user data on a novel game-based visual interface for stroke gait training. Study participants will complete one session comprising exposure to gait biofeedback systems in an order determined by block randomization (3 blocks). Participants will be exposed to 3 types of biofeedback interfaces:

• the anterior ground reaction forces (AGRF) biofeedback game (projector-display, non-augmented reality [AR])
• AR version of the biofeedback game (head-mounted AR display)
• traditional, non-game-based, interface

Stroke is the leading cause of adult disability. Even after discharge from rehabilitation, residual gait deficits are prevalent in stroke survivors, leading to decreased walking speed and endurance. Because gait dysfunctions limit community mobility, stroke survivors and rehabilitation clinicians consider restoration of walking a major goal of rehabilitation. Several challenges and research gaps limit the effectiveness of current clinical gait rehabilitation practices. While there is consensus that stroke survivors benefit from gait rehabilitation, agreement is lacking on which specific training interventions are most efficacious. The long-term goal of this proposal is to address these challenges by developing personalized, engaging, salient gait training treatments founded on evidence from neuroscience, biomechanics, motor learning, and gaming.

Real-time biofeedback is a promising gait training intervention for targeting specific biomechanical impairments. Biofeedback can enhance an individual's awareness of the impairment targeted during gait training, enabling self-correction of aberrant gait patterns.

In response to treadmill training combined with visual and auditory real-time biofeedback, able-bodied individuals can increase AGRF unilaterally for the targeted limb. Thus, AGRF biofeedback may be a beneficial strategy to target unilateral propulsive deficits in people post-stroke. Incorporation of gaming interfaces for gait biofeedback can increase patient motivation, distract participants from fatigue or boredom, and encourage greater numbers of repetitions during gait training.

The long-term goal of this study is to develop a more engaging, motivating gait biofeedback methodologies specifically designed for post-stroke gait training. The researchers aim to address a major challenge for rehabilitation clinicians - to make gait training appealing and meaningful so that patients engage in sufficient repetitions, intensity, and challenge to maximize therapeutic effectiveness. The study premise is that post-stroke individuals will demonstrate greater engagement, motivation, and therapeutic benefits during gait training sessions involving biofeedback when training incorporates intuitive, entertaining, game-based interfaces. Outcomes of the study will include measures of participant engagement, user-reports and survey-responses on motivation, fatigue, game characteristics, and adverse effects (e.g. nausea, dizziness) during game exposure. In addition to this clinical trial with stroke survivor participants, data about the game interface will be collected by having able-bodied neuro-rehabilitation clinicians try the 3 types of biofeedback interventions.

• Gait, Hemiplegic
• Stroke

• Other: Game without AR
  During the AGRF biofeedback game without augmented reality (AR) participants will walk on a split-belt treadmill with a projector-display. Participants will be receiving real-time information or feedback about ongoing gait performance parameters while they are walking. The participants will be exposed to the AGRF biofeedback game without AR for 6 minutes.
  Other Name: gait training
• Other: Game with AR
  During the AGRF biofeedback game with augmented reality (AR) participants will walk on a split-belt treadmill with a head-mounted AR display. Participants will be receiving real-time information or feedback about ongoing gait performance parameters while they are walking. The participants will be exposed to the AGRF biofeedback game with AR for 6 minutes.
  Other Name: gait training
• Other: Traditional Biofeedback Interface
  For the traditional non-game biofeedback, the visual display comprises a horizontal line graph with a moveable cursor that represents the current measured value of antero-posterior ground reaction force for the targeted leg. The auditory feedback comprises an audible "beep" produced every time the cursor entered the target range. Participants will be exposed to the traditional biofeedback interface for 6 minutes.
  Other Name: gait training

• Game without AR, Game with AR, Traditional Interface
  Post-stroke participants randomized to receive the three gait training biofeedback interfaces in the order of: game without AR, game with AR, traditional interface
  Interventions:

  • Other: Game without AR
  • Other: Game with AR
  • Other: Traditional Biofeedback Interface
• Game without AR, Traditional Interface, Game with AR
  Post-stroke participants randomized to receive the three gait training biofeedback interfaces in the order of: game without AR, traditional interface, game with AR
  Interventions:

  • Other: Game without AR
  • Other: Game with AR
  • Other: Traditional Biofeedback Interface
• Game with AR, Game without AR, Traditional Interface
  Post-stroke participants randomized to receive the three gait training biofeedback interfaces in the order of: game with AR, game without AR, traditional interface
  Interventions:

  • Other: Game without AR
  • Other: Game with AR
  • Other: Traditional Biofeedback Interface
• Game with AR, Traditional Interface, Game without AR
  Post-stroke participants randomized to receive the three gait training biofeedback interfaces in the order of: game with AR, traditional interface, game without AR
  Interventions:

  • Other: Game without AR
  • Other: Game with AR
  • Other: Traditional Biofeedback Interface
• Traditional Interface, Game without AR, Game with AR
  Post-stroke participants randomized to receive the three gait training biofeedback interfaces in the order of: traditional interface, game without AR, game with AR
  Interventions:

  • Other: Game without AR
  • Other: Game with AR
  • Other: Traditional Biofeedback Interface
• Traditional Interface, Game with AR, Game without AR
  Post-stroke participants randomized to receive the three gait training biofeedback interfaces in the order of: traditional interface, game with AR, game without AR
  Interventions:

  • Other: Game without AR
  • Other: Game with AR
  • Other: Traditional Biofeedback Interface

Inclusion Criteria for Post-Stroke Participants:

• chronic stroke (>6 months post stroke)
• ambulatory with or without the use of a cane or walker
• able to walk for 2 minutes at the self-selected speed without an orthoses
• resting heart rate 40-100 beats per minute

Exclusion Criteria for Post-Stroke Participants:

• cerebellar signs (ataxic ("drunken") gait or decreased coordination during rapid alternating hand or foot movements
• history of lower extremity joint replacement
• inability to communicate with investigators
• neglect/hemianopia, or unexplained dizziness in last 6 months
• neurologic conditions other than stroke
• orthopedic problems in the lower limbs or spine (or other medical conditions) that limit walking or cause pain during walking