Research team and PI reviewing if study design actually captures results to address primary and secondary outcomes.

The researchers have developed games controlled by electromyographic (EMG) and inertial measurement unit (IMU) activity recorded by a sensor. These will provide biofeedback to participants post-stroke about the activity of their paretic muscles. The researchers anticipate that providing visual biofeedback will allow subjects to observe the level of co-activation in an agonist-antagonist muscle pair, and therefore initiate interventions to reduce their level of co-activation. Similarly, the researchers will provide additional haptic feedback using an assistive robot at the ankle joint (i.e., M1) and compare the results with the pure visual feedback condition. At the end, the main objective is to compare 1) conventional robotic continuous passive movement (CPM) training to 2) training with visual biofeedback and 3) training with both visual and haptic biofeedback.

Post-stroke patients will be recruited when they are referred to Shirley Ryan AbilityLab's stroke rehabilitation outpatient clinics at Shirley Ryan Ability Lab's flagship hospital, or satellite SRAlab locations (e.g. Arlington Heights, Wheeling, Glenview, Homewood, Northbrook, or Burr Ridge) or participate in SRALab inpatient rehabilitation. The researchers will also recruit from local physicians or from the Clinical Neuroscience Research Registry (CNRR). Furthermore, participant interest and eligibility may also be confirmed from the patient medical record. If eligible and interested, they will be consented and enrolled, and the location of research visits will be based on participant preference: at SRAlab's flagship hospital (355 E Erie St, Chicago, 60611) or at SRAlab Burr Ridge (7600 County Line Road, Burr Ridge, 60527). Eligible participants will then be randomized (using a pre-generated sequence of block randomization numbers) to receive either 1) conventional robotic CPM training, 2) training with visual biofeedback (games) or 3) training with visual (game) and haptic (robotic assistance) biofeedback. Participants will complete a 60 min session to perform 30 minutes of their assigned type of training. The goal of this study is to compare the efficacy of the three different rehabilitation training conditions.

For each condition, 3 sessions per week for a total of 4 weeks will be completed in addition to the daily PT sessions. Each training session will be 60 min long and include experimental setup, vitals monitoring (i.e., blood pressure, heart rate, oxygen saturation level), and training time. The maximum training time for each session will be 30 minutes. For healthy participants, they will use their dominant foot for all training sessions, designated by asking the healthy participant the question "which leg do you use to kick a ball?". For clinical participants, they will use their affected/weaker foot for all training sessions.

Full clinical assessments will be performed before (T0), mid (T3) and after (T6) training sessions, as well as 1 month after finishing all training sessions and 3 months after finishing all training sessions. Note that additional 180 min will be allotted before or after the 60 min training session to perform all clinical assessments: Flexion/extension range of motion (ROM), Maximal Volitional Electromyographic Activity (MVEA), Maximum Voluntary Contraction Torque (MVCT), Modified Ashworth Scale (MAS), 10-Meter Walk Test (10MWT), 6-Minute Walk Test (6MWT), Berg Balance Scale (BBS), Functional Gait Assessment (FGA).

After the final training session at T6, patients will complete a subjective experience survey: Game Experience, Stroke Specific Quality of Life (SSQoL), Short Form 36.

CONDITION 1 - CONTINUOUS PASSIVE MOVEMENT (CPM) TRAINING. At the beginning of the session, the participant's vitals (i.e., blood pressure, heart rate, oxygen saturation level) will be measured. Participants will then be seated and secured to the chair with a gait belt and the research personnel will assist with the placement of their limb into the M1 device. Velcro straps will be adjusted to prevent movement between the M1 device and the participant's foot. The shank Velcro straps will also be adjusted to provide support to the knee. Three sensors will then be placed either on the tibialis anterior (TA) or extensor halluces longus (EHL), vastus lateralis (VL) and biceps femoris longus (BF), and soleus (S) or gastrocnemius (GAS) muscles on the designated limb after cleaning the skin with alcohol prep pads by a researcher. Then, the ROM of the ankle joint, MVEA and MVCT of the ankle will be measured. The participant will then be asked to perform up to 30 min of ankle CPM training. The trajectory, ROM, and rate of oscillations provided during the CPM training will vary according to the participant's functional capacity. The total session time will be 60 min, including the vital measurements, experimental setup, and CPM training.

CONDITION 2 - VISUAL FEEDBACK. At the beginning of the session, the vitals will be measured. Participants will then be seated and secured to the chair with a gait belt and the research personnel will assist with the placement of their limb into the M1 device. Velcro straps will be adjusted to prevent movement between the M1 device and the participant's foot. Shank Velcro straps will also be adjusted to provide support to the knee. Three sensors will then be placed either on the tibialis anterior (TA) or extensor halluces longus (EHL), vastus lateralis (VL) and biceps femoris longus (BF), and soleus (S) or gastrocnemius (GAS) muscles on the designated limb after cleaning the skin with alcohol prep pads by a researcher. Then, the ROM of the ankle joint, MVEA and MVCT of the ankle will be measured. Based on the ROM of the ankle, the movement of the game avatar will be adjusted (calibrated so that the ROM of the participant corresponds to the maximum movement required by the avatar to play the game). Participants will perform 30 min of training with visual biofeedback (games). Participants will be observed while playing the games to note any software challenges they may encountered while playing.

CONDITION 3 - HAPTIC + VISUAL FEEDBACK. At the beginning of the session, the vitals will be measured. Participants will then be seated and secured to the chair with a gait belt and the research personnel will assist with the placement of their limb into the M1 device. Velcro straps will be adjusted to prevent movement between the M1 device and the participant's foot. Shank Velcro straps will also be adjusted to provide support to the knee. Three sensors will then be placed either on the tibialis anterior (TA) or extensor halluces longus (EHL), vastus lateralis (VL) and biceps femoris longus (BF), and soleus (S) or gastrocnemius (GAS) muscles on the designated limb after cleaning the skin with alcohol prep pads by a researcher. Then, the ROM of the ankle joint, MVEA and MVCT of the ankle will be measured. Based on the ROM of the ankle, the movement of the game avatar and assistance provided by the M1 device will be adjusted (calibrated). Participants will perform up to 30 min of training with visual biofeedback (games) and haptic biofeedback. The assistive torque that is provided by the M1 robot with respect to the EMG signals will be adjusted according to the participant. Participants will be observed while playing the games to note any software or hardware challenges they may encountered while playing.

Inclusion Criteria for Healthy Participants:

• 18 - 80 years of age, inclusive
• Normal hearing and vision, can be corrected
• Participants must have muscle sites appropriate for biofeedback (see below)
• Participants must have a minimum active flexion angle of 15 degrees and a minimum extension angle of 10 degrees.
• No skin allergies to adhesive material or paste
• No neurological disorders
• Absence of pathology that could cause abnormal movements of extremities (e.g., epilepsy, stroke, marked arthritis, chronic pain, musculoskeletal injuries)
• Able to understand and give informed consent

Inclusion Criteria for Participants Post-Stroke:

• 18 - 80 years of age, inclusive
• Normal hearing and vision, can be corrected
• Participants must have muscles sites appropriate for biofeedback (see below)
• No skin allergies to adhesive material or paste
• Unilateral, supratentorial ischemic or hemorrhagic stroke ≥ three months prior
• Participants must have a minimum activation against gravity for dorsiflexion and plantar flexion, equivalent to a Manual Muscle Test (MMT) score of greater than or equal to +2
• Ability to walk >10m independently on level ground, allowed to use assistive devices or bracing as needed
• Self-selected walking speed is less than 0.8 meters/sec
• Medical clearance from primary medical team (signed Medical Clearance form)
• No concurrent surgeries, medical treatments, participation in research, or outpatient physical therapy
• Able to understand and give informed consent
• Able to understand and speak English

Exclusion Criteria for Healthy Participants:

• Comorbid traumatic brain injury
• Premorbid cognitive limitations that would prevent playing games
• Adults unable to consent, pregnant women, children, or prisoners
• Implantable pacemaker, spinal stimulator, or vagal nerve stimulator
• Known skin allergies to silver
• The overlying skin on recording areas has any infection, wounds, or graft sites
• Potential biofeedback muscles do not have detectable electromyographic activity (this will be tested after subjects are consented and enrolled)
• History of sustained non-prescribed drug use (as reported by subject) or substance abuse (exception: current nicotine use is allowed)
• Prior neurosurgical procedures
• History of peripheral nerve injury
• Severe hip, knee, or ankle arthritis
• Recent fracture or osteoporosis (as reported by subject)
• Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures
• Inability or unwillingness to perform study-required activities

Exclusion Criteria for Participants Post-Stroke:

• Comorbid traumatic brain injury
• Premorbid cognitive limitations that would prevent playing games
• Adults unable to consent, pregnant women, children, or prisoners
• Implantable pacemaker, spinal stimulator, or vagal nerve stimulator
• Known skin allergies to silver
• The overlying skin on recording areas has any infection, wounds, or graft sites
• Potential biofeedback muscles do not have detectable electromyographic activity (this will be tested after subjects are consented and enrolled)
• Botox (botulinum toxin) injection to lower limbs within the prior 3 months, or planned injection during study period
• Significant spasticity or contracture in the lower limbs (Modified Ashworth Scale score of 4)
• History of sustained non-prescribed drug (as reported by subject) use or substance abuse (exception: current nicotine use is allowed)
• Reduced cognitive function and unable to perform study tasks
• Severe aphasia
• Co-existence of other neurological diseases (e.g., Parkinson's disease or other neurodegenerative disorder, severe dementia, brain injury, spinal cord injury, multiple sclerosis, or cancer of the central nervous system)
• History of peripheral nerve injury
• Severe hip, knee, or ankle arthritis
• Recent fracture or osteoporosis (as reported by subject)
• Medical (cardiac, renal, hepatic, oncological) or psychiatric disease that would interfere with study procedures
• Inability or unwillingness to perform study-required activities