Cerebrovascular Responses to Aerobic Exercise in Young Healthy non-Hispanic Black and White Males

Non-Hispanic Black (BL) adults experience a higher burden of cerebrovascular disease compared with other racial and ethnic groups, for which impaired cerebrovascular function is a well-established risk factor. Previous studies have shown that at rest, cerebrovascular function is lower in young BL adults compared with young WH adults. However, cerebrovascular responses to exercise have never been investigated in BL adults. We hypothesized that young BL males would exhibit attenuated cerebrovascular responses to aerobic exercise compared with their WH counterparts. Cerebrovascular (i.e., middle cerebral artery mean blood velocity; MCAvmean, cerebrovascular conductance index; CVCi and cerebral pulsatility index; PI), cardiovascular (i.e., brachial blood pressure and heart rate), and respiratory (i.e., VO₂ and CO₂) variables were measured at rest and during incremental and steady-state semi-recumbent cycling exercise in 13 BL and 11 WH males. At rest there were no differences between groups for cerebrovascular, cardiovascular and respiratory measures (all p>0.05). Groups were also comparable for cardiorespiratory fitness (VO₂peak, BL:39.5±5.1 vs WH:39.7±6.2 mL/kg/min, p=0.92). During exercise, MCAvmean increased similarly in both groups for both incremental (intensity:p<0.01, race: p=0.44, interaction: p=0.57; e.g., at 50%VO₂peak, BL: ∆16.2±4.3 vs WH: ∆15.7±8.7 cm/s) and steady-state (intensity:p<0.01, race: p=0.45, interaction: p=0.98; e.g., at 50 watts, BL: ∆5.8±2.3 vs WH: ∆4.8±5.0 cm/s) exercise. There was also no main effect of race for CO₂, CVCi or PI during either exercise protocol (all p>0.05). Thus, contrary to our hypothesis, no detectable racial differences in cerebrovascular responses to incremental or steady-state aerobic exercise were found in this cohort of young, otherwise healthy males.