Mechanisms behind the protective effects of aerobic exercise on brain health remain elusive but may be vascular in origin and relate to cerebral pulsatility. This pilot study investigated the effects of 12 wks aerobic exercise training on cerebral pulsatility and its vascular contributors (large artery stiffness, characteristic impedance) in at-risk middle-aged adults. 28 inactive middle-aged adults with elevated blood pressure or stage 1 hypertension were assigned to either moderate/vigorous aerobic exercise training (AET) for 3 d/wk or no-exercise control (CON) group. Middle cerebral artery (MCA) pulsatility index (PI), large artery (i.e., aorta, carotid) stiffness, and characteristic impedance were assessed via Doppler and tonometry at baseline, 6, and 12 wks, while cardiorespiratory fitness (VO2peak) was assessed via incremental exercise test and cognitive function via computerized battery at baseline and 12 wks. VO2peak increased 6% in AET and decreased 4% in CON (p<0.05). Proximal aortic compliance increased (p=0.04, partial η2=0.14) and aortic characteristic impedance decreased (p=0.02, partial η2=0.17) with AET but not CON. Cerebral pulsatility showed a medium-to-large effect size increase with AET, although not statistically significant (p=0.07, partial η2=0.11) compared to CON. Working memory reaction time improved with AET but not CON (p=0.02, partial η2=0.20). Our data suggest 12-wk AET elicited improvements in central vascular hemodynamics (e.g. proximal aortic compliance and characteristic impedance) along with apparent, paradoxical increases in cerebral pulsatile hemodynamics.
Keywords: Exercise adaptations; arterial stiffness; cerebral pulsatility; hypertension; large artery hemodynamics.