A MECHATRONIC TOOL FOR REVEALING INVERSE RELATIONSHIPS AMONG HEART’S STROKE VOLUME AND HEAD’S LINEAR ACCELERATION INDUCED BY MOORED BOATS ROLLING IN ELDERLY SAILORS WITH UNCHANGED BODY SIZES: A NON-DRUG ANTI-HYPERTENSIVE ADVANTAGE?

Three aged and skilled sailors, being in a good condition of cardio metabolic compensation, took a seven days coastal sailing cruise. They daily underwent a cardiodynamic assessment by a impedance cardigraphy tool while staying seated on the moored boat. They showed a statistically significant inverse linear regression of beat-to-beat left ventricular stroke volume (LSV) versus the component of the head acceleration along the spatial X-axis, positioning the subject’s head so that the X-axis lay along the nose-ocipital direction. In fact, the temporally corresponding values of LSV inversely changed of about 11 ml on average, with an interindividual difference ranging from a minimum of about 6 ml to a maximum of about 14 ml, for each unitary head acceleration change. Since the reduction of left ventricular stroke volume may be due to the already observed vestibulo-sympathetic reflex from which limbs muscle vasodilation may occur, and considering that LSV falling induces a reduction in arterial blood pressure, it is hypothesized that the slow rolling of moored boat might also act as a non-invasive arterial blood pressure attenuator effect.