New insights into the effects of age and sex on arterial baroreflex function at rest and during dynamic exercise in humans

Abstract

The arterial baroreflex (ABR) performs an important role in regulating blood pressure (BP) both at rest and during exercise, by carefully orchestrating autonomic neural activity to the heart and blood vessels. Reduced ABR sensitivity (i.e., gain) has been associated with increased cardiovascular risk, cardiac electrical instability and orthostatic intolerance, while 'normal' ABR function during exercise is important for ensuring an appropriate cardiovascular response is elicited. Previous studies examining the influence of age and sex on resting ABR function in humans have primarily used pharmacological methods (e.g., modified Oxford technique) to change BP and alter baroreceptor input. With this approach only reflex control of heart rate and sympathetic nerve activity may be evaluated, and as such the influence of age and sex on ABR control of BP per se remains incompletely understood. Furthermore, the majority of previous studies examining ABR function during exercise have principally assessed young men. Whether these findings can be extrapolated to young women or older men and women remains unclear. Recently the potential for age and sex to modulate the integrative neural control of the cardiovascular system is becoming appreciated. This review article will provide a detailed update of such recent advances into our understanding of the effects of age and sex on ABR control of BP both at rest and during dynamic exercise in humans.