Impact of passive vibration on pressure pulse wave characteristics.

The augmentation index (AIx), a marker of wave reflection, decreases following acute leg exercise. Passive vibration (PV) causes local vasodilation that may reduce AIx. This study investigated the effects of acute PV on wave reflection and aortic hemodynamics. In a crossover fashion 20 (M=9, F=11) healthy young (22±3 year) participants were randomized to 10 min PV or no vibration control (CON) trials. Subjects rested in the supine position with their legs over a vibration platform for the entire session. Radial waveforms were obtained by applanation tonometry before and after 3 min (Post-3) and 30 min (Post-30) of PV (∼5.37 G) or CON. No change in parameters was found at Post-3. We found significant time-by-trial interactions (P<0.01) at Post-30 for augmented pressure, AIx and second systolic peak pressure (P2), such that these parameters significantly (P<0.05) decreased (-2.3±3.0 mm Hg, -7.2±6.9% and -1.5±3.5 mm Hg, respectively) after PV but not after CON. These findings suggest that acute PV applied to the legs decreases AIx owing to a decrease in wave reflection magnitude (P2). Further research is warranted to evaluate the potential clinical application of PV in populations at an increased cardiovascular risk who are unable to perform conventional exercise.

Post-exercise aortic hemodynamic responses to low-intensity resistance exercise with and without vascular occlusion.

High-intensity resistance exercise may acutely increase arterial stiffness. Vascular occlusion (VO) acutely decreases arterial stiffness. The purpose of this study was to evaluate acute aortic hemodynamic responses to low-intensity resistance exercise (LIRE) with slow eccentric movement with and without VO. Twenty-three young healthy subjects (12 women and 11 men) were randomized into three trials: seated control (CON), LIRE (six sets at 40% one repetition maximum), and LIRE with VO. Vascular measurements were assessed before, immediately (post1), and 30 min after (post30) each trial. There were significant (P<0.05) time effects and trial-by-time interactions such that the changes were greater after the LIRE trials compared with CON. Aortic blood pressure [systolic (∼10 mmHg) and diastolic (∼5 mmHg)], heart rate (∼23 b.p.m.), and the first (∼10 mmHg) and second systolic peak (∼9 mmHg) increased, whereas time to reflection decreased (∼15 ms) at post1. All measurements returned to baseline at post30, except aortic augmentation index (AIx), which decreased ∼5% after the LIRE trials compared with CON. Increases in cardiovascular variables immediately after the LIRE trials were mild and short lasting. Our results indicate that LIRE acutely decreases AIx 30 min after exercise cessation. The use of moderate intermittent VO during LIRE does not produce additional post-exercise vascular effects.