Tracking Neural Synergies After Stroke.

The purpose of this study is to identify neural muscle synergies of patients post-stroke and track them during an inpatient acute rehabilitation. To this end, the researchers will use an innovative approach based on the identification of large populations of motor units from recordings of surface high-density electromyography (HD-EMG).

The researchers will focus on the identification of neural muscle synergies of leg and thigh muscles during postural and locomotor tasks in patients post stroke. To this end, the researchers will recruit 20 patients participating in inpatient rehabilitation at Shirley Ryan AbilityLab in the early subacute phase after stroke and 20 age-matched healthy controls. The researchers will ask them to perform postural tasks and walking trials at their preferential speed. All assessments will be performed by a licensed physiotherapist as per the standard of care once a week during three weeks of inpatient rehabilitation at the Shirley Ryan AbilityLab. During these tasks, the researchers will record HD-EMG signals from four muscle groups (Quadriceps, Hamstrings, Triceps Surae, Tibialis anterior).

Eligibility Criteria:
Healthy participants:

Inclusion Criteria:

* Age 18-85 years old
* Ambulatory with or without an assistive device
* Ability to stand unassisted for at least 15 min
* Informed consent provided by participant
* English speaking

Exclusion Criteria:

* Inability to communicate with researchers
* Lower extremity joint pain, contractures
* Major sensory deficits, or cardiovascular or respiratory symptoms contraindicative of walking
* History or evidence of orthopedic, muscular, or physical disability
* Taking current medications that may affect balance
* History or evidence of vestibular, auditory, or proprioceptive impairment
* History or indication of orthostatic hypotension
* History of any neurological disease
* Open wounds on surfaces in contact with HD-EMG electrodes
* Concurrent participation in other lower limb research studies that according to the PI is likely to affect study outcome or confound results
* Pregnancy

Patients:

Inclusion Criteria:

* Age 18-85 years old
* Unilateral, supratentorial ischemic or hemorrhagic stroke within the past six months
* Medical clearance from primary medical team (signed Medical Clearance form)
* Unassisted sitting balance at edge of mat or hospital bed ≥ 30 seconds
* Baseline Visible muscle contraction in hip flexors, knee extensors, and ankle dorsiflexors ( ≥1 MMT) or manual resistance against one muscle group (\>3 MMT)
* Adequate cognitive function as determined by the NIH scale: score ≤1 on question 1b and score =0 on question 1c
* Informed consent provided by participant or POA
* English speaking

Exclusion Criteria:

* Severe aphasia limiting ability to express needs or discomfort verbally or nonverbally
* Severe behavioral neglect
* History of prior stroke
* Concurrent neurologic condition (i.e PD, TBI, MS, etc.)
* History of peripheral nerve injury
* Joint contracture or significant spasticity in the lower limbs (Modified Ashworth Scale ≥3)
* Severe knee, hip, or ankle osteoarthritis
* Severe osteoporosis as indicated by physician medical clearance
* Open wounds on surfaces in contact with HD-EMG electrodes
* Unstable spine or unhealed fractures
* Weight bearing precautions
* Unresolved deep vein thrombosis (DVT)
* Concurrent participation in other lower limb research studies that according to the PI is likely to affect study outcome or confound results
* Pregnancy