Ischemic Conditioning Improves Microvascular Reactivity to Single Passive Limb Movement in the Paretic Leg of Chronic Stroke Survivors

Background: Individuals post-stroke have impaired peripheral vascular reactivity throughout all stages of stroke recovery, which could contribute to suboptimal physical function. Ischemic conditioning (IC) is a therapeutic stimulus known to improve large artery vasodilation post-stroke. However, it is unknown whether IC improves the downstream microvasculature, which vasodilates to supply blood flow to active skeletal muscle. A simple, clinically relevant way to measure microvascular health is with single passive limb movement (sPLM), which causes an acute increase in leg blood flow (LBF) and microvascular vasodilation, without an increase in muscle metabolism. We hypothesized that a single bout of IC versus sham-IC would improve the microvascular response to sPLM in the paretic and non-paretic legs of individuals with chronic stroke. Methods: This is a randomized, controlled, blinded, cross-over clinical trial (NCT05935670). Participants sat in a Biodex dynamometer that passively moved their leg 90 degrees at a frequency of 1 Hz. We measured superficial femoral artery blood flow and diameter at rest and during sPLM (3 trials separated by 2 minutes). We then randomized participants to receive IC or sham-IC and placed a thigh cuff around the paretic leg, repetitively inflating to 225 mmHg for IC or 25 mmHg for sham-IC for 5 min, then deflating for 5 min, for a total of 45 minutes. Immediately following IC or sham-IC, we reassessed sPLM with the assessor blinded to the condition. We calculated the microvascular response as the percent change in LBF (%∆LBF) from baseline (average 10 seconds prior to sPLM) to peak. Results: Fifteen individuals with chronic stroke have completed the study (9 females, age 62 ± 10 years old, 7.8 ± 6.1 years post-stroke). When controlling for resting heart rate and leg blood flow between days, there was a significant condition x time interaction effect (p = 0.02) on the %∆LBF to sPLM in the paretic leg (∆IC: 7.33 ± 27.91 vs ∆Sham: 6.99 ± 22.93). However, there was no significant interaction effect of remote IC on the %∆LBF to sPLM in the non-paretic leg (p = 0.61). Conclusion: We demonstrate that a single bout of ischemic conditioning (IC) enhances microvascular reactivity to movement in the paretic leg of individuals with chronic stroke compared to sham IC. In contrast, a single bout of IC did not elicit a significant remote effect in the non-paretic leg, possibly indicating that direct local IC may be required for improvements in microvascular reactivity post-stroke. Future analyses will include comparing the microvascular response in individuals with chronic stroke to their age- and sex-matched neurologically intact controls, as well as examining associations between microvascular health, clinical measures of disability, and muscle strength following IC. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.