Ischemic Conditioning Improves Walking Function Post Stroke

This innovative study will address scientific and clinical areas relatively unexplored in chronic stroke that could lead to greater recovery of walking. Ischemic Conditioning (IC) is a non-invasive, simple procedure that improves motor function, exercise performance and cardiovascular function in healthy controls, but it has never been applied to the stroke population. We postulate that IC enhances the recruitment of motoneurons and results in positive neural adaptations, improves vascular endothelial function and peripheral blood flow, and together these improvements result in an increased capacity to exercise and faster walking speed. Future studies will examine the effects of IC and traditional therapy at different time points of recovery post stroke, durability of IC, molecular mechanisms of neural and cardiovascular adaptation and the efficacy compared with other adjuncts.

This study will quantify the effects of Ischemic Conditioning and treadmill training on improvements in: walking speed, leg strength, neuromuscular fatigability and the hyperemic blood flow response to muscle contractions, and vascular endothelial function and aerobic exercise capacity. A randomized control design will be used with three groups of chronic stroke survivors enrolled for four weeks of training (3x/week; 12 sessions total). The groups are: IC + Treadmill Training, IC Sham + Treadmill Training, and IC only. We will also enroll a group of age- and sex-matched healthy control subjects who will undergo IC + Treadmill Training. All Aims will be tested concurrently over a five-year period. All studies will be performed in Cramer Hall at Marquette University in the Integrated Neural Engineering Rehabilitation Laboratories, the Human Performance Assessment Core, and the Physical Therapy Clinic.

Randomization of stroke patients to the three intervention groups will be performed by using randomized block designs (randomly chosen block sizes of 3, 6 and 9). This number accounts for possible dropouts and the use of non- parametric methods.

Eligibility Criteria:
Inclusion Criteria (Stroke Survivors):

1. be ≥ 1 year post diagnosis of a unilateral, cortical stroke and have residual lower extremity paresis
2. be between the ages of 18-85
3. be able to give informed consent
4. walk slower than normative values based on age and sex

Exclusion Criteria (Stroke Survivors):

1. history of deep vein thrombosis or any condition in which transient ischemia to the lower extremity is contraindicated
2. inability to follow 2 step commands
3. chronic low back or hip pain
4. history of substance abuse
5. history of head trauma
6. comorbid neurological disorder
7. any uncontrolled medical condition
8. pacemaker
9. any condition where fatiguing contractions or resisted leg contractions are contraindicated
10. inability to walk for 5 minute bouts on a treadmill with a harness supporting up to 50% of the body weight at 80% of over-ground self-selected walking speed.

Inclusion Criteria (Healthy Control Subjects):

1. be between ages of 18-85
2. be able to give informed consent

Exclusion Criteria (Healthy Control Subjects):

1. Those listed above for stroke survivors
2. History of Stroke