On the Cardiovascular Effects of Whole‐Body Vibration Part I. Longitudinal Effects: Hydrodynamic Analysis

Abstract

For a given direction of whole‐body vibration and a given piece of blood vessel, the local vibration has in general both a longitudinal (parallel) component and a lateral (perpendicular) component. The longitudinal and lateral effects are treated in Part I and Part II, respectively. In Part I, detailed hydrodynamic analysis shows that the maximal shear stress at the wall of the vessel is considerably increased by the longitudinal component of vibration for big vessels. For example, for high frequency range 40–50 Hz, the maximal shear stress at the wall of coronary artery could increase by 35–49% even if the local longitudinal amplitude is as small as 50 μm. Potential benefits and risks associated with this effect are discussed. In Part II, statistical analysis is carried out based on the results of specially designed experiments, where accelerations at different body locations and some cardiovascular parameters were measured simultaneously. Some changes of body mode were arranged during the vibration experiments in a way that the transmissibility of vibration increased considerably during each change of body mode. Statistical analysis of the results suggests with high level of confidence (>97%) that arterioles were dilated during such changes of body mode. Potential benefits associated with this effect are discussed.