Moderate-Intensity Exercise Versus High-Intensity Interval Training to Recover Walking Post-Stroke

The objective of this study is to determine the optimal training intensity and the minimum training duration needed to maximize immediate improvements in walking capacity in chronic stroke. A single-blind, phase II, 3-site randomized controlled trial has been planned. Fifty persons \>6 months post stroke will randomize to either moderate-intensity aerobic locomotor training or high-intensity interval locomotor training; each for 45 minutes, 3x/week for up to 36 total sessions over approximately 12 weeks. Clinical measures of walking function, aerobic fitness, daily walking activity and quality of life will be assessed at baseline (PRE) and after 4, 8 and 12 weeks of training (POST-4WK, POST-8WK, POST-12WK).


Eligibility Criteria:
Inclusion Criteria:

1. Age 40-80 years at time of consenting
2. Single stroke for which participant sought treatment, 6 months to 5 years prior to consent date
3. Walking speed \<1.0 m/s on the 10-meter walk test
4. Able to walk 10m over ground with assistive devices as needed and no continuous physical assistance from another person (guarding and intermittent assistance for loss of balance allowed)
5. Able to walk at least 3 minutes on the treadmill at ≥0.13m/s (0.3 mph)
6. Stable cardiovascular condition (AHA class B, allowing for aerobic capacity \<6 metabolic equivalents)
7. Able to communicate with investigators, follow a 2-step command and correctly answer consent comprehension questions

Exclusion Criteria:

1. Exercise testing uninterpretable for ischemia or arrhythmia (e.g. resting ECG abnormality that makes exercise ECG uninterpretable for ischemia and no other clinical testing from the past year available to rule out)
2. Evidence of significant arrhythmia or myocardial ischemia on treadmill ECG graded exercise test in the absence of recent (past year) more definitive clinical testing (e.g. stress nuclear imaging) with negative result
3. Hospitalization for cardiac or pulmonary disease within past 3 months
4. Implanted pacemaker or defibrillator
5. Significant ataxia or neglect (score of 2 on NIH stroke scale item 7 or 11)
6. Severe lower limb spasticity (Ashworth \>2)
7. Recent history (\<3 months) of illicit drug or alcohol abuse or significant mental illness
8. Major post-stroke depression (Patient Health Questionnaire \[PHQ-9\] ≥ 10) in the absence of depression management by a health care provider
9. Currently participating in physical therapy or another interventional study
10. Recent botulinum toxin injection to the paretic lower limb (\<3 months) or planning to have lower limb botulinum toxin injection in the next 4 months
11. Foot drop or lower limb joint instability without adequate stabilizing device, as assessed by a physical therapist
12. Clinically significant neurologic disorder other than stroke or unable to walk outside the home prior to stroke
13. Other significant medical condition likely to limit improvement or jeopardize safety as assessed by a physical therapist (e.g. joint contracture, gait limited by pain)
14. Pregnancy
15. Previous exposure to fast treadmill walking (\>3 cumulative hours) during clinical or research therapy in the past year