Cardiorespiratory fitness is associated with increased middle cerebral arterial compliance and decreased cerebral blood flow in young healthy adults: A pulsed ASL MRI study

Abstract

Cardiorespiratory fitness is thought to have beneficial effects on systemic vascular health, in part, by decreasing arterial stiffness. However, in the absence of non-invasive methods, it remains unknown whether this effect extends to the cerebrovasculature. The present study uses a novel pulsed arterial spin labelling (pASL) technique to explore the relationship between cardiorespiratory fitness and arterial compliance of the middle cerebral arteries (MCAC). Other markers of cerebrovascular health, including resting cerebral blood flow (CBF) and cerebrovascular reactivity to CO₂ (CVR_CO2) were also investigated. Eleven healthy males aged 21 ± 2 years with varying levels of cardiorespiratory fitness (maximal oxygen uptake (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mrow><mml:mi>V</mml:mi></mml:mrow><mml:mi>·</mml:mi></mml:mover></mml:mrow></mml:math>O_2MAX) 38-76 ml/min/kg) underwent MRI scanning at 3 Tesla. Higher <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mrow><mml:mi>V</mml:mi></mml:mrow><mml:mi>·</mml:mi></mml:mover></mml:mrow></mml:math>O_2MAX was associated with greater MCAC (R²= 0.64, <i>p</i> < 0.01) and lower resting grey matter CBF (R²= 0.75, <i>p</i> < 0.01). However, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mrow><mml:mi>V</mml:mi></mml:mrow><mml:mi>·</mml:mi></mml:mover></mml:mrow></mml:math>O_2MAX was not predictive of global grey matter BOLD-based CVR (R²= 0.47, <i>p</i> = 0.17) or CBF-based CVR (R²= 0.19, <i>p</i> = 0.21). The current experiment builds upon the established benefits of exercise on arterial compliance in the systemic vasculature, by showing that increased cardiorespiratory fitness is associated with greater cerebral arterial compliance in early adulthood.