Robotic Exosuit Augmented Locomotion (REAL)

Previous 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 lost function. 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 long-lasting gait restoration. Current gait training efforts are focused on either quality or intensity. They focus on gait quality often by reducing the training intensity to allow patients to achieve a more normal gait. In contrast, efforts focused on training intensity push participants without focusing on the quality of their movements. These intervention paradigms generally fail to substantially impact community mobility. In this study, the investigators posit that exosuits can uniquely enable an integration of these paradigms (ie, high intensity gait training that promotes quality of movements). For this protocol, exosuits developed in collaboration with an industry partner, ReWalk™ Robotics will be used. To evaluate the effects of REAL gait training, the investigators will use clinical measures of motor and gait function, locomotor mechanics and energetics, and physiologic measures that may infer on motor learning. The spectrum of behavioral and physiologic data that we will collect will enable us to understand more comprehensively the gait-restorative effects of REAL.

Weakness of the ankle plantarflexors after a stroke results in impaired forward propulsion during walking, which consequently impacts walking efficiency and speed - parameters that are necessary for community participation. Next-generation soft, wearable robots, known as soft robotic exosuits, were developed to assist paretic ankle dorsiflexion during its swing phase and paretic ankle plantarflexion during push off. Prior observational studies of the exosuit technology have culminated in strong evidence of immediate gait-restorative effects for patients post-stroke through improved forward propulsion, and faster and farther walking. The investigators posit that gait training using exosuits will leverage these immediate gait-restorative effects to facilitate gait training at higher intensities without compromising gait quality. This type of training will facilitate lasting rehabilitative effects that persist beyond the use of exosuit. Leveraging a systematic approach in the staging of pilot studies toward larger clinical trials, this clinical validation was initiated with a single-subject study design followed by a case series, which both provided early evidence for the potential of gait training with exosuits in restoring propulsion and speed. As a next step, the investigators seek to examine the efficacy of these interventions under more robust terms by implementing a randomized clinical trial (RCT).

The primary aim of the current study seeks to understand the rehabilitative effects of a Robotic Exosuit Augmented Locomotion (REAL) gait training program relative to matched gait training without exosuits (Control) on walking and propulsion function after stroke. It is hypothesized that REAL training will result in clinically meaningful improvements in walking speed that are greater than the speed gains following Control training. Further, this study seeks to examine whether training-related changes in propulsion function following both interventions (REAL, Control) influence the training-induced effects on walking function. The investigators hypothesize that REAL training will result in substantial gains in walking function that are achieved through improved propulsion function, while Control training will have modest gains in walking function that are not related to changes in propulsion.

A secondary aim of this study is to evaluate single day changes in neuromuscular control following both interventions (REAL, Control), as measured by muscle synergies and the dynamic motor control index. The investigators hypothesize that neuromuscular control will immediately improve during powered use of a soft-robotic exosuit (i.e., immediate) and exosuit-induced improvements in neuromuscular control will show continued improvement over a single session of REAL gait training (i.e., adaptation), and persisting improvement to unassisted walking after a single session of REAL gait training (i.e., retention). In contrast, the Control training will show no changes in neuromuscular control. An additional secondary aim is to identify neuromuscular predictors of training-related improvements in walking and propulsion function. It is hypothesized that positive relationships will be observed between single-day changes in neuromuscular control and training-induced improvements in walking and propulsion function after 12 sessions of gait training. Moreover, the investigators hypothesize that regardless of baseline walking speed, individuals with higher baseline neuromuscular control will have the greatest training-induced improvements in propulsion and walking function after 12 sessions of gait training.

For this protocol, exosuits developed in collaboration with an industry partner (ReWalk™ Robotics) will be used. To examine the effects of REAL gait training, the investigators will use clinical measures of motor and gait function, locomotor mechanics, and physiologic measures that may infer on motor learning. The spectrum of behavioral and physiologic data that will be collected will enable a more comprehensive understanding of the gait-restorative effects of REAL.

This study will be implemented by carrying out the following study visits: (1) Primary screen over the phone, (2) Clinical screen \& fit, (3) Exposure, (4) Pre-training evaluations, (5) Training (12 sessions)(6) Post-training evaluation, and (7) Retention evaluation. Randomization to either REAL or Control will occur after Pre-training evaluation. A washout period up to 4 weeks will precede Retention evaluation.

Eligibility Criteria:
Inclusion Criteria:

* Age 18 - 80 years old
* Stroke event occurred at least 6 months ago
* Observable gait deficits
* Gait speed equal to or less than 1 m/s
* Able to walk without the support of another person for at least 6 minutes (may use an assistive device as needed, but without use of an ankle foot orthosis or brace)
* Passive ankle dorsiflexion range of motion to neutral with the knee extended (i.e., able to achieve an angle of 90 degrees between the shank and the foot)
* Resting heart rate between 40 - 100 bpm, inclusive
* Resting blood pressure between 90/60 and 170/90 mmHg, inclusive

Exclusion Criteria:

* Score of \>1 on question 1b and \>0 on question 1c on the NIH Stroke Scale
* Inability to communicate with investigators
* Neglect or hemianopia
* Actively receiving physical therapy for walking
* History of cerebellar strokes
* Known recurring or repeating strokes
* Unexplained dizziness in the last 6 months
* Pressure ulcers or skin wounds located at human-device interface sites
* Other medical, orthopedic, and neurological conditions that prevent full participation in the research