Effects of Soft Robotic Exosuit on Exercise Capacity, Biomakers of Neuroplasticity, and Motor Learning After Stroke

High intensity exercise is known to improve a person's ability to learn new motor skills. The goal of this project is to evaluate if a robotic exosuit can help people who have had a stroke perform walking rehabilitation at higher intensities than they are able to without the exosuit. The investigators will measure exercise training intensity, biomarkers of neuroplasticity (e.g., brain-derived neurotrophic factor; BDNF), and motor learning when people poststroke exercise with and without the exosuit. For this protocol, exosuits developed in collaboration with ReWalk™ Robotics will be used.

Aim 1: Determine the effects of a soft robotic exosuit on gait training intensity and serum BDNF in persons post-stroke completing a single bout of high intensity walking.

Hypothesis 1: Exosuits will allow individuals post-stroke to (i) walk at higher intensities or (ii) walk at a high intensity for longer durations.

Hypothesis 2: Training at a higher intensity, or training at high intensity for longer durations, will result in increased serum BDNF.

Aim 2: Determine the effects of a soft robotic exosuit on gait biomechanics measured after a single bout of high intensity walking with versus without a soft robotic exosuit.

Hypothesis 3: A single bout of high intensity walking with an exosuit will lead to demonstrably better gait biomechanics than a single bout of high intensity exercise without an exosuit.

Prior studies of the exosuit technology have culminated in strong evidence for the gait-restorative effects of soft robotic exosuits for patients post-stroke by means of substitution for impaired paretic limb function during walking. The present study builds on this work by suggesting that an exosuit's immediate gait-restorative effects can be leveraged during high intensity gait training to produce post-training improvements in gait quality. Indeed, current rehabilitation efforts are focused on either quality or intensity. They focus on gait quality by reducing the training intensity to allow patients to achieve a more normal gait. In contrast, efforts focused on training intensity push participants without regard for the quality of their movements. The investigators posit that exosuits can uniquely enable high intensity gait training that promotes quality of movements.

Acute bouts of high intensity exercise prior to skilled task practice have been shown to enhance motor learning in neurologically intact individuals. However, the impact of high intensity exercise on motor learning in clinical populations remains largely unknown. A major limitation to studying this relationship in survivors of stroke are challenges in achieving and maintaining high intensity exercise levels (\>75% max HR) during gait training for durations that are comparable to neurologically intact individuals. Exercising at a lower intensity or for a shorter duration may result in insufficient neurological "priming" for motor learning that typically follows high intensity training-which would be evidenced in reduced production of activity-dependent markers of neuroplasticity (e.g., brain-derived neurotrophic factor; BDNF). For this study, the investigators will use standardized, maximal effort tests to evaluate the ability of a soft robotic exosuit to increase a patient's capacity for high intensity gait training. The investigators will also examine the resulting effect on BDNF and the relationship between training intensity, BDNF and motor learning measures.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of stroke
* Chronic phase of recovery (\>6mo post-stroke) (self-report)
* 18-80 years old (self-report)
* Independent ambulation (with or without an assistive device) for at least two minutes (confirmed at secondary screening visit)
* Provide HIPAA Authorization to allow communication with the healthcare provider as needed during the study period
* Medical clearance by the participant's physician

Exclusion Criteria:

* Score of \> 1 on question 1b and \> 0 on question 1c on the NIH Stroke Scale (NIHSS)
* Inability to communicate
* Unexplained dizziness in the last 6 months
* Serious comorbidities that may interfere with the ability to participate in this research (for example: musculoskeletal, cardiovascular, pulmonary, and neurological - other than stroke)
* Anemia (defined as hemoglobin levels of \<13 g/dL for men and \<12 g/dL for women)
* Clotting disorders\*\*
* Have given blood to any other entity within 60 days prior to blood collection
* History of significant Peripheral Artery Disease (PAD)
* Unresolved Deep Vein Thrombosis (DVT)
* Uncontrolled or untreated hypertension
* Significant paretic ankle contractures (plantarflexion \> 5°)
* Psychiatric or cognitive impairments that may interfere with the proper operation of the device
* Presence of open wounds or broken skin at device locations requiring medical management
* Known urethane allergies
* Pregnancy

  * Note: If the study team suspects neglect or hemianopia at any time during the course of the research, the physical therapist may administer the Star Cancellation Test (https://www.strokengine.ca/en/assess/sct/) for neglect or a visual field test (e.g., showing visual stimuli on different sides of the body) for hemianopia.

    * Note: We may enroll participants who do not have a clotting disorder, but who are on anti-clotting medications.