Stroke is a leading cause of disability in the United States, affecting approximately 795,000 people annually. The Veteran's Health Administration provides over 60,000 outpatient visits for stroke-related care annually at a cost of over $250 million. Among ambulatory people with chronic stroke (PwCS), impaired balance is a common health concern that substantially limits mobility (those with the worst balance walk the least). This project will explore adaptive strategies employed by PwCS in balance challenging environments and if a novel gait training intervention using a robotic device to amplify a person's self-generated movements can improve walking balance. The development of effective interventions to increase walking balance among PwCS will positively impact Veterans' health, quality of life, and ability to participate in walking activities.
History of chronic stroke (more than 6 months post-stroke) with weakness on one side
Ability to ambulate over ground for 10 meters with or without a single cane, and/or ankle-foot orthosis
Ability to tolerate 10 minutes of standing
Presence of cognitive impairment (score of 22/30 on the Montreal Cognitive Assessment scale (MoCA))
Presence of aphasia (score of 71/100 on the Mississippi Aphasia Screening Test (MAST))
Excessive spasticity in lower limbs (score of > 3 on the Modified Ashworth Scale
Severe cardiovascular and pulmonary disease affecting gait and balance
Single group
High intensity gait training in varying external environments
BehavioralParticipants will engage in two 45-minutes treadmill-based gait training sessions. These training sessions will occur on separate days. One session will be performed in a natural unmodified environment. One session will be performed in a movement amplification environment. The goal of each session will be to achieve 40-minutes of walking within a target heart rate range of 70-85% of estimated heart rate max. Each session will begin and end with a 2.5 minute warm-up and cool down respectively. Participants will be given rest breaks as needed.
Treadmill walking in varying external environments
BehavioralParticipants will perform a series of treadmill walking trials. Each trial will consist of 400 total steps. The first 100 steps will be performed in a natural unmodified environment. The next 200 steps will be performed in 1 of 3 external environments (natural unmodified, movement amplification, or unpredictable lateral perturbations). The final 100 steps will be performed in a natural unmodified environment. Participants will be given rest breaks between trials.
Lateral center of mass (COM) excursion during walking
Lateral COM excursion is the peak-to-peak distance the COM moves from side-to-side during a complete gait cycle. This distance is measured in meters. Smaller values indicate better ability to control motion during walking.
Minimum lateral margin of stability
Minimum lateral margin of stability is the smallest distance between the lateral extrapolated center of mass position (XCOM) and the lateral base of support (BOS), approximated as the lateral position of the 5th metatarsal marker on the side of the last initial contact. Minimum MOS is identified during stance phase of each step. Extrapolated center of mass (XCOM) position is calculated using: XCOM= COM + COM\* l/g The minimum lateral margin of stability is calculated in meters. Smaller values indicate greater ability to control motion during walking.
Heart Rate
Participants heart rate in beats per minute (bpm) will be collected to determine cardiovascular response to exercise. Larger heart rates will indicate a stronger cardiovascular response to exercise.
Perceived Exertion (RPE)
Participants exertion monitored via 6-20 point rate of perceived exertion scale and heart rate will be collected to determine participants performance during each training session and track their progress. Minimum score for perceived exertion is 6 and maximum score is 20. Higher score indicates greater exertion and lower score indicates less exertion.
Step Length
Step length is calculated as the fore-aft distance between the calcanei markers at initial foot contact. This distance is measured in meters. Larger values indicate longer steps.
Step Width
Step width is calculated as the medio-lateral distance between the left and right 5th Metatarsal markers at initial foot contact. This value is measured in meters. Larger values indicate a wider step.
10 Meter Walk Test (10MWT)
10MWT is a simple measurement of an individual's average walking speed measured at self-selected speed (instruction: "walk at your normal comfortable pace") and fastest-possible speed (instruction: "as fast as you safely can").
Timed Up and Go (TUG)
TUG is used to assess functional mobility, walking balance, and fall risk. It is a quick, valid, reliable and widely used clinical performance based measure in individuals post-stroke. While there is no time limit to the TUG test, more time taken to finish the task indicates poor balance and greater fall-risk.
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VA Office of Research and Development
Lead sponsor
Northwestern University
Collaborator
