Impaired Microvascular Reactivity to Passive Limb Movement After Stroke Is Improved by a Single Session of Ischemic Conditioning

Background Microvascular dysfunction post stroke remains insufficiently investigated and may contribute to impairments in physical function. Single passive limb movement (sPLM) provides a clinically relevant assessment of microvascular vasodilation. We hypothesized the response to sPLM would be attenuated in the paretic leg compared with age‐ and sex‐matched controls (CON) and would improve following a single session of ischemic conditioning (IC), an intervention known to enhance vasodilation. Methods In this randomized crossover trial, superficial femoral artery leg blood flow was measured during sPLM, using a Biodex dynamometer, which passively moved the leg 90° at 1 Hz. A thigh cuff was placed around the paretic leg (dominant leg in CON) and inflated to 225 mm Hg for IC or 25 mm Hg for sham‐IC for 5 minutes, followed by 5 minutes deflation, repeated for 45 minutes. A blinded assessor remeasured the sPLM response, calculated as the percentage of change in peak leg blood flow relative to baseline. Results Fifteen individuals post stroke (62±10 years old, 60% female, 8±6 years post stroke) and fifteen CON completed the study. The microvascular response to sPLM was lower in the paretic leg ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:semantics> <mml:mrow> <mml:mover accent="true"> <mml:mi>x</mml:mi> <mml:mo stretchy="true">¯</mml:mo> </mml:mover> </mml:mrow> <mml:annotation encoding="application/x-tex">$$ \overline{x} $$</mml:annotation> </mml:semantics> </mml:math> =47%±19%) compared with CON ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:semantics> <mml:mrow> <mml:mover accent="true"> <mml:mi>x</mml:mi> <mml:mo stretchy="true">¯</mml:mo> </mml:mover> </mml:mrow> <mml:annotation encoding="application/x-tex">$$ \overline{x} $$</mml:annotation> </mml:semantics> </mml:math> =65%±36%, P =0.04) but not the nonparetic leg ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:semantics> <mml:mrow> <mml:mover accent="true"> <mml:mi>x</mml:mi> <mml:mo stretchy="true">¯</mml:mo> </mml:mover> </mml:mrow> <mml:annotation encoding="application/x-tex">$$ \overline{x} $$</mml:annotation> </mml:semantics> </mml:math> =56%±34%, P =0.10). IC improved the microvascular response to sPLM in the paretic leg ( P =0.02) but not the nonparetic leg or CON ( P ≥0.68). Conclusions Individuals post stroke exhibited impaired movement‐induced microvascular vasodilation in the paretic leg. A single session of IC acutely improved the paretic leg's response, potentially supporting local IC as an adjunct therapy to enhance microvascular health before neurorehabilitation.