Effects of ischemic conditioning on microvascular reactivity to single passive limb movement in young adults: a pilot study.

Purpose: Single passive limb movement (sPLM) of the lower extremity is a simple and clinically relevant measure of the microvascular vasodilatory response to movement. A promising stimulus to improve microvascular health is ischemic conditioning (IC). We examined whether a single session of IC could improve microvascular reactivity to sPLM in young adults.

Methods: This was a blinded, crossover, randomized clinical trial. Participants were seated in an isokinetic dynamometer that passively moved the knee 90° at a frequency of 1 Hz while superficial femoral artery leg blood flow (LBF) was measured. The absolute and the relative peak changes in LBF were calculated as the difference from baseline. The time to peak was calculated from the start of sPLM to peak LBF. The total area under the curve (AUC) was the sum of LBF above baseline during the hyperemic response. For IC, the cuff was placed around the dominant thigh and repetitively inflated (225 mmHg) for 5 min, then deflated for 5 min (total 45 min). For sham IC, the cuff was inflated to 25 mmHg. The sPLM response was re-assessed ten minutes after IC.

Results: Twelve individuals completed the study (age 27 ± 3 years, 50% female). When controlling for resting LBF, heart rate, and sex, there was an interaction effect for absolute and relative peak change in LBF (p ≤ 0.048) but not time to peak or total AUC (p ≥ 0.17).

Conclusion: We show an acute bout of IC may improve the peak vasodilatory response to sPLM, potentially due to "preconditioning" the microvasculature.