The Relationship Between Aerobic Fitness and Brachial Endothelial Function on Cerebrovascular Regulation

Abstract

Aging is associated with declining function of peripheral (i.e., brachial) and cerebral (i.e., middle cerebral artery) arteries, which increases the risk for the development of cardiovascular and cerebrovascular disease. Higher levels of aerobic fitness counteract some of these age-related reductions in brachial artery function. However, the impact of aerobic fitness on cerebral artery function is less certain. This project aims to explore whether aerobic fitness and brachial endothelial function are related to cerebrovascular regulation in younger and older adults. The present project assessed the hypothesis that higher aerobic fitness would be positively associated with brachial flow-mediated dilation (FMD) outcomes and resting middle cerebral artery velocity (MCAv), but the relationship between cerebrovascular reactivity (CVR), aerobic fitness and brachial FMD is unclear, given differing reports in the literature. Aerobic fitness (V̇O2peak, via indirect calorimetry), as well as brachial FMD (via duplex ultrasonography), MCAv (via transcranial Doppler) and CVR (MCAv response to breath holding), were assessed in a group of healthy younger (n=15) and older (n=14) adults. Relative and absolute V̇O2peak were not related to brachial-FMD, MCAv or CVR (all, p>0.179). Brachial-FMD was not related to MCAv or CVR (both, p>0.08). These results indicate that aerobic fitness was not related to brachial FMD or cerebrovascular outcomes in a group of younger and older adults. Furthermore, brachial endothelial function may not be indicative of cerebrovascular function in younger and older adults.