VARIABILITY IN POPLITEAL ARTERY BLOOD FLOW : EFFECT OF EXERCISE TRAINING
Mean arterial pressure (MAP) is regulated through changes in cardiac output (Q) and total peripheral resistance (TPR), where Q = heart rate (HR) x stroke volume (SV). Healthy heart rhythms have inherent variability and a decrease in heart rate variability (HRV) is associated with cardiovascular disease. Our preliminary data suggested there was variability in peripheral blood flow as well and it was predicted that aerobically trained women (TR) would demonstrate greater popliteal artery blood flow variability compared to untrained (UT). Additionally, improvements in endothelial cell function (ECF) have been associated with exercise training and it was predicted that TR would show greater ECF through flow-mediated dilation (FMD) than UT and that FMD would be related to popliteal artery blood flow variability. Resting, prone popliteal artery blood flow (ml/min), diameter (cm) and time averaged blood velocity (TAV; m/s) were measured at 1 min intervals for 10 min using Doppler Ultrasound in trained (TR, N = 10) and untrained (UT, N = 8) young females. Brachial artery systolic and diastolic blood pressures were measured simultaneously with blood flow, mean arterial pressure (MAP) was estimated, and popliteal artery conductance (1/popliteal artery resistance) was calculated from MAP and popliteal artery blood flow. Means and standard deviations (SD) were calculated from the 10 x 1 min measures and SD was used as a measure of variability. A 5 min occlusion of the calf was used to induce a hyperemic response in the popliteal artery and flow-mediated dilation (FMD) was measured using Doppler Ultrasound during and following the occlusion period. Student's t-test, l mixed model 2x2 ANOVA, and linear regression were used to analyze data. Mean resting popliteal artery blood flow was similar between groups (43.9 ml/min TR vs. 56.8 ml/min UT; p = 0.15). Popliteal artery blood flow variability was similar between TR and UT young women, with a trend toward greater variability in UT (15.1 ml/min TR vs. 19.8 ml/min UT; p = 0.07). TR participants exhibited a larger arterial diameter at rest compared to UT (0.57 ± 0.01cm TR vs. 0.51 ± 0.01cm UT; p = 0.02). When FMD was corrected for resting diameter (%), there was no difference in maximum FMD between groups (10.9% TR vs. 6.7% UT; p = 0.27). Resting blood flow variability was found to be moderately correlated with resting popliteal artery conductance (r = 0.69; p < 0.01), but not resting MAP (r = -0.12; p = 0.64) or maximum FMD (r = 0.05; p = 0.86). Contrary to the hypothesis, TR subjects did not demonstrate greater resting popliteal artery blood flow variability or greater FMD compared to UT. Resting popliteal artery blood flow variability was not related to maximum FMD, but was moderately correlated to resting popliteal artery conductance.
Kehe, Sarah. (January 2012). VARIABILITY IN POPLITEAL ARTERY BLOOD FLOW : EFFECT OF EXERCISE TRAINING (Master's Thesis, East Carolina University). Retrieved from the Scholarship. (http://hdl.handle.net/10342/3951.)
Kehe, Sarah. VARIABILITY IN POPLITEAL ARTERY BLOOD FLOW : EFFECT OF EXERCISE TRAINING. Master's Thesis. East Carolina University, January 2012. The Scholarship. http://hdl.handle.net/10342/3951. July 17, 2018.
Kehe, Sarah, “VARIABILITY IN POPLITEAL ARTERY BLOOD FLOW : EFFECT OF EXERCISE TRAINING” (Master's Thesis., East Carolina University, January 2012).
Kehe, Sarah. VARIABILITY IN POPLITEAL ARTERY BLOOD FLOW : EFFECT OF EXERCISE TRAINING [Master's Thesis]. Greenville, NC: East Carolina University; January 2012.
East Carolina University