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Reactive hyperemia tests create mismatches in oxygen (O2 ) delivery and demand by occluding blood flow to skeletal muscle. We tested the hypothesis that skeletal muscle reactive hyperemia is dependent on the specific deoxygenation stimulus. We hypothesized that the magnitude of deoxygenation (Δ=nadir-baseline) would correlate with the magnitude of the reactive hyperemic response (Δ=peak-baseline), whereas the total deoxygenation would correlate with the total reactive hyperemic response. In six (3M:3F) young adults, we continuously measured forearm blood flow using doppler ultrasound on the brachial artery and muscle O2 saturation during three reactive hyperemia tests (1, 5, or 10 minutes in duration). The magnitude of deoxygenation was significantly (P < 0.05 via paired t-test) less during 1 min occlusion (-13±1.6%) compared to 5 min occlusion (-67±14%; P=0.0015) or 10 min occlusion (-74±10%; P=0.0004), but 5 min vs 10 min occlusion were not different (P=0.40). Similarly, the magnitude of the RH was greater in both the 10 min occlusion (329±102 ml/min; P=0.0004) and 5 min occlusion (295±123 ml/min; P=0.005) vs 1 min occlusion (131±69 ml/min; P < 0.0001), but not different from one another (P=0.11). However, total deoxygenation increased progressively from 1 min (-335±51 units), to 5 min (-10732±2209 units), to 10 min (-32357±5053 units; all P < 0.01) as did total reactive hyperemic response (1 min:1326±927 ml; 5 min:7865±4055 ml; 10 min:17447±9698 ml; P < 0.01). These results suggest the reactive hyperemia response is determined by the absolute magnitude of deoxygenation and total difference between O2 supply and demand. Prolonged deoxygenation in the 10 min occlusion led to a greater reactive hyperemia response, potentially mediated by increased muscle metabolite production and greater bioavailability of vasoactive products mediated by fully deoxygenated erythrocytes.
Primary Advisor's Department
Health and Sport Science
Stander Symposium, School of Education and Health Sciences
Institutional Learning Goals
"Skeletal Muscle Reactive Hyperemia Is Dependent on the Deoxygenation Stimulus in Young Healthy Humans" (2023). Stander Symposium Projects. 2837.