Peripheral vasoconstrictor reflex for whole body transient vibrations

Photo‐plethysmographic blood volume pulse amplitude was observed on five male subjects on the middle finger phalanx of the right hand under whole body impression of transient vibrations of three types, such as, one shot shock motion (SSM), one period sinusoidal vibration with an ultralow frequency (OPV), and one short burst random vibration (SBR) on a vertical vibration table. The pattern of the plethysmogram, of which amplitude decreased abruptly as called vasoconstriction and recovered gradually until certain constant amplitude observed at rest condition, was not affected by the transient vibrations of the three types. The vasoconstriction was commonly enforced with increasing the amplitude of the transient vibrations and in addition the vasoconstriction was influenced by the factors for the transient vibrations, that is, the duration for SSM, the fundamental frequency for the OPV, and the built‐up time for the SBR. The relation between the vasoconstriction and these factors was quantified from the variance analysis in the experimental design method.