Passive Limb Movement Study

Study Overview
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Brief Summary
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Stroke survivors have compromised vascular function which may contribute to secondary stroke risk, cardiovascular disease, and may limit their exercise tolerance. No studies have examined how femoral blood flow responds to both passive leg movement, a measure of microvascular function, as well as active leg contractions, a measure of the hyperemic response to exercise. Leg muscles with a reduced blood flow response to movement could be associated with decreased neuromuscular function, such as leg strength and fatigue. Preliminary data showing a single bout of ischemic conditioning may improve vascular function and muscle activation in healthy adults and individuals post-stroke. Therefore, the investigators want to examine if ischemic conditioning will also improve the blood flow response to passive leg movements as well as during single leg active contractions.

Official Title
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Passive Limb Movement Study

Conditions
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Stroke, Vascular Diseases, Ischemic

Intervention / Treatment
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* Device: Ischemic Conditioning


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Individuals Post-Stroke 18 - 85 years of age Cortical or sub-cortical stroke ≥ 6 months ago with residual hemiparesis Able to give informed consent and follow 2-step command. English Speaking Age- and Sex-Matched Controls (CON) Matched to age of individual post- stroke ± 5 years. Matched to sex of individual post-stroke Able to give informed consent and follow 2-step command. English Speaking Young Healthy Adults (CONyoung) Age 18-30 years old Able to give informed consent and follow 2-step command. English Speaking Exclusion Criteria: All Groups Unable to stand from chair and walk 10 meters without physical assistance from another person (able to use assistive device). History of blood clots in the extremities or any condition in which compression of the thigh or transient ischemia is contraindicated (i.e., wounds in the leg). Chronic lasting symptoms (> 6 months) of severe COVID-19 (i.e., hospitalization) Low back or hip pain that limits lower extremity motor testing. History of head trauma or concussion within the past 6 months Comorbid neurological disorder Peripheral vascular disease Myocardial infarction in the previous year Condition where fatiguing contractions or resisted leg contractions are contraindicated Resting SBP ≥180 mmHg or DBP ≥ 100 mmHg Pregnancy or breastfeeding. Other significant medical condition likely to influence study or jeopardize safety as assessed by the Primary Investigator CON and CONyoung History of Stroke

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 85 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: The investigators will enroll and complete visits for 30 individuals within the study including individuals post-stroke (n = 10), their age- and sex-matched controls (CON, n = 10), and young healthy controls (CONyoung, n = 10). This study includes 2 visits to the Athletic and Human Performance Research Center (AHPRC) at Marquette University. The investigators will measure femoral blood flow to passive limb movement and active contractions pre-/post- ischemic conditioning high (225 mmHg) and ischemic conditioning low (25 mmHg).
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Ischemic Conditioning - High<br>During each testing session, the investigators will be measuring how one treatment of ischemic conditioning effects leg blood flow and muscle function. One day participants will receive a high cuff inflation pressure on the leg, called ischemic conditioning - high (225 mmHg). | Device: Ischemic Conditioning<br>* The cuff will be placed around the proximal, paretic thigh (or dominant thigh for controls) and inflated for 5 minutes in a supine or semi-reclined position, then released for a 5-minute recovery period. Five cycles of inflation and recovery will be performed (45 minutes total).These inflations will be done using a cuff similar to what is used for taking blood pressure.<br>|
| Experimental: Ischemic Conditioning - Low<br>During each testing session, the investigators will be measuring how one treatment of ischemic conditioning effects leg blood flow and muscle function. One day participants will receive a low cuff inflation pressure on the leg, called ischemic conditioning - low (25 mmHg). | Device: Ischemic Conditioning<br>* The cuff will be placed around the proximal, paretic thigh (or dominant thigh for controls) and inflated for 5 minutes in a supine or semi-reclined position, then released for a 5-minute recovery period. Five cycles of inflation and recovery will be performed (45 minutes total).These inflations will be done using a cuff similar to what is used for taking blood pressure.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ultrasound Measured Femoral Blood Flow during Passive Limb Movement (PLM) | Microvascular response to single passive leg movement | Change from Baseline PLM Femoral Blood Flow after IC (3 hours) | 
| Ultrasound Measured Femoral Blood Flow during Active Limb Contraction | Hyperemic Response to Maximal Voluntary Contractions (MVCs) | Change from Baseline MVCs Femoral Blood Flow after IC (3 hours) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ultrasound measured Femoral Blood Flow following Neuromuscular Fatigue Task | Hyperemic Response to Fatiguing Muscle Contractions | Post Ischemic Conditioning (15 minutes) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ischemic Conditioning, Blood Flow, Peripheral Microvascular Function, Neuromuscular Function