Non-invasive assessment of the changes in static and oscillatory components of peripheral pressure/flow relationships produced by moderate exercise in humans

Objective. The generalized sympathetic activation induced by exercise is accompanied by an increase in heart rate, blood pressure and vascular resistance in non-exercising vascular beds. The aim of the present study was to test the feasibility of assessing, non-invasively, the static and oscillatory pressure/flow relationships of peripheral arteries and their continuous changes during dynamic exercise. Design. We studied 44 healthy humans at rest, during moderate exercise (recumbent bicycle exercise) and recovery using a totally non-invasive approach. Methods. Arterial pressure was measured using a plethysmographic device, and ipsilateral brachial artery flow and palmar skin microcirculation flow were assessed with continuous wave Doppler and laser Doppler, respectively. Continuous, long data segments > 90 s) were acquired with a personal computer and used to determine the changes of pressure/flow relationships of peripheral arteries during dynamic exercise. A new simplified method utilizing a transfer function analysis extracted automatically unequivocal indexes of static and oscillatory properties of vascular system. Results. Moderate exercise induced significant increases of the static (Z(o)) and oscillatory (Z(c)) components of peripheral pressure/flow relationships in both brachial artery and skin microcirculation beds. Both indexes returned to control values during early recovery. Conclusions. This simple, non-invasive approach was capable of assessing the changes of static and oscillatory vascular properties induced by dynamic exercise. This method could be applied for a better understanding of the vascular modifications that occur in other physiological or pathophysiological conditions also characterized by increases in sympathetic drive.