Long Term Endurance Exercise Training Ameliorates Conduit Artery Retrograde and Oscillatory Shear in Older Adults

Abstract

With aging, there tends to be an increase in retrograde and oscillatory shear in peripheral conduit arteries of humans. Whether the increase in shear rate is due to the aging process or an effect of a less than active lifestyle that often accompanies aging is unknown. Therefore, in a cross‐sectional study we evaluated whether chronic endurance exercise training attenuates retrograde and oscillatory shear in older adults. Brachial and common femoral artery mean blood velocities and diameter were determined via Doppler ultrasound under resting conditions in 13 young (Y = 24 ± 1 years), 17 older untrained (OU = 66 ± 1 years), and 16 older endurance exercise trained adults (OT = 66 ± 2 years). Mean shear rate (s−1) was defined as 4·Vm/D, where Vm is mean blood velocity (cm · s−1) and D is arterial diameter (cm). For calculations of antegrade and retrograde shear rate, antegrade and retrograde mean blood velocities were used, respectively. Oscillatory shear index is an indicator of the magnitude of oscillation between antegrade and retrograde shear. Vascular resistance in the forearm and leg were also calculated (mean arterial pressure/blood flow) using each respective limb blood flow and mean arterial pressure derived from beat‐to‐beat finger plethysmography measurements. Brachial artery retrograde (−9.1 ± 1.7 vs. −12.6 ± 2.3 s−1; P = 0.35) and oscillatory (0.14 ± 0.02 vs. 0.14 ± 0.02 arbitrary units; P = 0.99) shear were similar between the OT and OU groups, whereas brachial retrograde and oscillatory shear were greater in OU compared to Y adults (−5.0 ± 0.9 s−1, 0.08 ± 0.01 arbitrary units, both P < 0.05; respectively). There was no difference between the Y and OT brachial artery retrograde (P = 0.29) and oscillatory (P = 0.07) shear. Common femoral artery retrograde (−6.3 ± 0.7 s−1) and oscillatory (0.21 ± 0.02 arbitrary units) shear was reduced in OT compared to the OU group (−10.4 ± 1.0 s−1 and 0.30 ± 0.02 arbitrary units, both P < 0.05; respectively), yet similar to Y adults (−7.1 ± 1.0 s−1 and 0.19 ± 0.02 arbitrary units, P = 0.81 and 0.87; respectively). Vascular resistance did not differ between groups in the arm (P = 0.56) or the leg (P = 0.32). However, vascular resistance was inversely related to retrograde shear in the brachial and common femoral artery (r = −0.33 and −0.37, both P < 0.05; respectively) and positively related to oscillatory shear in the brachial and common femoral artery (r = 0.46 and 0.54, both P < 0.05; respectively) when all subjects were pooled together. Our results suggest that chronic endurance exercise training in older adults ameliorates retrograde and oscillatory shear rate patterns, particularly in the common femoral artery.Support or Funding InformationResearch was supported by NIH HL‐105467 (DPC)