Pulsatile Load and Wasted Pressure Effort are Reduced Following an Acute Bout of Aerobic Exercise

Following aerobic exercise, sustained vasodilation and concomitant reductions in total peripheral resistance (TPR) result in a reduction in blood pressure that is maintained for two or more hours. However, the time course for postexercise changes in reflected wave amplitude and other indices of pulsatile load on the left ventricle have not been thoroughly described. Therefore, we tested the hypothesis that reflected wave amplitude is reduced beyond an hour after cycling at 60% V̇O2peak for 60 min. Aortic pressure waveforms were derived in 14 healthy adults (7 men, 7 women; 26 ± 3 yr) from radial pulse waves acquired via high-fidelity applanation tonometry at baseline and every 20 min for 120 min postexercise. Concurrently, left ventricle outflow velocities were acquired via Doppler echocardiography and pressure-flow analyses were performed. Aortic characteristic impedance (Zc), forward (Pf) and backward (Pb) pulse wave amplitude, reflected wave travel time (RWTT), and wasted pressure effort were derived. Reductions in aortic blood pressure, Zc, Pf, and Pb were all sustained postexercise while increases in RWTT emerged from 60-100 min post exercise (all P<0.05). WPE was reduced by ~40% from 40-100 min post exercise (all P<0.02). Stepwise multiple regression analysis revealed that the peak ∆WPE was associated with ∆RWTT (β=-0.57, P=0.003) and ∆Pb (β=0.52, P=0.006), but not ∆cardiac output, ∆TPR, ∆Zc, or ∆Pf. These results suggest that changes in pulsatile hemodynamics are sustained for ≥100 min following moderate intensity aerobic exercise. Moreover, decreased and delayed reflected pressure waves are associated with decreased left ventricular wasted effort after exercise.