The proposed research will evaluate the individual and combined effects of task-specificity and intensity of rehabilitation interventions on locomotor function, community mobility and quality of life in patients with subacute (1-6 months) post-stroke.

The objective of this Phase II clinical trial is to identify how exercise training parameters, particularly the specificity and intensity of stepping practice, influence long-term mobility outcomes in patients with subacute stroke. Previous work indicates these variables can influence the efficacy of training interventions in individuals without neurological injury, with some data to support their utility in chronic stroke. However, studies that systematically assess the independent and combined effects of these principles in individuals early following stroke are sparse. This critical research gap impedes clinical translation, and current clinical practices remain adherent to traditional theories of rehabilitation, including lower intensity interventions focused on underlying impairments. Additional concerns of providing only high-intensity walking training revolve around the lack of attention toward movement quality will result in use of compensatory movement strategies that could be reinforced with repeated practice, or that other risks of cardiovascular events should preclude high-intensity training. Unfortunately, there is little data to support these hypotheses, and our studies suggest that application of these training parameters can strongly influence walking function, as well as improve underlying impairments and improve gait kinematics. Our approach is to characterize the effects of these training variables on recovery of locomotor function and quality, as well as changes in impairments and other mobility tasks in patients early post-stroke, in an effort to evaluate whether such training influences neurological recovery or whether patients utilize compensatory strategies. In this 2x2 factorial RCT design, Aim 1 of the study will characterize changes in mobility function associated with manipulation of specific and intensity of exercise interventions. We will evaluate functional measures of gait speed and endurance, spatiotemporal symmetry, as well as measures of cardiopulmonary fitness. We postulate that combined application of high-intensity, task specific stepping practice will result in significantly greater increases in locomotor measures as compared to lower intensity or non-specific training paradigms. In Aim 2, we will characterize the changes in impairments (strength) and other mobility tasks (balance, sit-to-stand transfers) to determine whether stepping intervention can mitigate the major impairments underlying post-stroke impairments. Quantitative measures of volitional strength will be the primary outcomes. In Aim 3, we will characterize changes in community mobility and quality of life, the later of which can inform us about cost-effectiveness. Overall, these results have potential implications on the delivery of effective exercise interventions in person with subacute stroke.

Inclusion Criteria:

• Sub-acute stroke (1-6 months)
• Hemiparesis (Fugl-Meyer <34) without cerebellar deficits
• Ability to ambulate with or without physical assistance over 10 meters but < 1.0 m/s and assistive devices and below-knee bracing is allowed.
• Ability to sit > 30 seconds without upper-extremity support or physical assistance
• Ability to follow 3-step commands
• Provision of informed consent and medical clearance from a supervising physician or medical provider to participate
• Must have the ability to consent or have a legal health care power of attorney or legally authorized representative to consent for participation on their behalf

Exclusion Criteria:

• Significant cardiovascular, metabolic, or respiratory disease that limits exercise participation (e.g. previous myocardial infarction < 3 months prior, uncompensated congestive heart failure, resting blood pressure > 210/110 mmHg, uncontrolled diabetes, end-stage renal disease, severe infectious or psychiatry disease, or advanced malignancy)
• If during the graded-treadmill exercise evaluation, the participant presents with absolute criteria for termination of exercise testing during initial testing (e.g. moderate to severe angina, ST elevation > 1.0mm without preexisting Q wave secondary to prior MI, signs of poor perfusion, etc).
• Any orthopedic or neurological disorders that limited walking to <50m prior to stroke onset.
• Cannot receive physical therapy once baseline testing begins
• If patients are prescribed botulinum toxin for their lower extremities will be excluded only if the dosage for any specific muscle is >50 units in leg muscles above the knee. If doses are > than 50 units in leg muscles below the knee, the participant will use an ankle-foot orthosis to minimze contributions of those mscles to locomotor function.

Currently Undecided

Blinded assessors will be utilized at baseline, post-training and follow-up assessments.