Department of Kinesiology, Iowa State University, Ames, Iowa.
Department of Kinesiology, University of Maryland, College Park, Maryland.
J Appl Physiol (1985). 2022 Oct 1;133(4):1019-1030. doi: 10.1152/japplphysiol.00371.2022. Epub 2022 Sep 8.
Cerebral hemodynamics and pulsatility are important mechanisms of cerebrovascular and brain health. Cardiorespiratory fitness may improve cerebrovascular pulsatility in healthy females, but not in males. Whether cardiovascular disease (CVD) risk factors modify sex-specific associations of fitness with cerebral hemodynamics and vascular contributors to cerebral hemodynamics is unknown. We assessed V̇o and cerebrovascular hemodynamics in 157 adults without (42 ± 13 yr, BMI 24.5 ± 2.7 kg/m), and 66 adults with modifiable CVD risk factors (54 ± 8 yr, BMI 29.9 ± 4.0 kg/m). Intracranial [middle cerebral artery (MCA) pulsatility index (PI), mean velocity, conductance, and pulsatile damping] and extracranial hemodynamics [carotid artery wave transmission/reflection, PI, pulse wave velocity (PWV)-β, and carotid-femoral PWV] were assessed via transcranial Doppler/ultrasound and tonometry. Cardiorespiratory fitness was assessed via V̇o during an incremental exercise test. Multiple regression was used to assess contributions of V̇o to cerebrovascular outcomes after adjustment for relevant covariates. V̇o was inversely associated with MCA PI among females (β = -0.39, = 0.01) but not males (β = -0.16, = 0.25) without CVD risk factors. V̇o was positively associated with MCA PI among females (β = 0.44, = 0.01) and not associated in males with CVD risk factors (β = -0.06, = 0.079). V̇o was beneficially associated with vascular contributors to cerebral hemodynamics but had sex-specific associations with carotid stiffness and pulse pressure in females without CVD risk factors only. These results suggest that sex-specific associations between fitness and cerebral pulsatility among females without CVD risk factors may relate to the differential effects of fitness on carotid stiffness and pulse pressure. In addition, the presence of modifiable CVD risk factors may influence the protective relations of fitness on cerebrovascular hemodynamics. We identify beneficial associations between cardiorespiratory fitness and lower carotid stiffness and pulse pressure as potential mechanisms underlying sex-specific associations of fitness and cerebral pulsatility in females without modifiable risk factors. Greater fitness is beneficially associated with conductance, pulsatile damping, and forward wave energy among adults without risk factors; however, associations are attenuated among adults with modifiable risk factors. These data suggest sex and risk factors may alter cerebrovascular sensitivity to cardiorespiratory fitness.
脑血流动力学和脉动性是脑血管和大脑健康的重要机制。心肺适应能力可能会改善健康女性的脑血管脉动性，但不会改善男性的脑血管脉动性。心血管疾病（CVD）危险因素是否会改变与健康女性和男性的脑血管血流动力学和脑血管血流动力学的血管贡献相关的适应能力的性别特异性关联尚不清楚。我们评估了 157 名无（42±13 岁，BMI 24.5±2.7kg/m）和 66 名可改变的 CVD 危险因素成年人的 V̇o 和脑血管动力学（54±8 岁，BMI 29.9±4.0kg/m）。通过经颅多普勒/超声和张力测量评估颅内（大脑中动脉（MCA）脉动指数（PI）、平均速度、传导率和脉动阻尼）和颅外血流动力学（颈动脉波传输/反射、PI、脉搏波速度（PWV）-β和颈动脉-股动脉 PWV）。心肺适应性通过递增运动试验中的 V̇o 评估。多元回归用于在调整相关协变量后评估 V̇o 对脑血管结局的贡献。在无 CVD 危险因素的女性中，V̇o 与 MCA PI 呈负相关（β=-0.39， =0.01），但在男性中则没有（β=-0.16， =0.25）。在无 CVD 危险因素的女性中，V̇o 与 MCA PI 呈正相关（β=0.44， =0.01），但在有 CVD 危险因素的男性中则没有关联（β=-0.06， =0.079）。V̇o 与脑血管血流动力学的血管贡献呈有益关联，但仅在无 CVD 危险因素的女性中与颈动脉僵硬和脉压呈性别特异性关联。这些结果表明，在无 CVD 危险因素的女性中，适应能力与大脑搏动性之间的性别特异性关联可能与适应能力对颈动脉僵硬和脉压的不同影响有关。此外，可改变的 CVD 危险因素的存在可能会影响适应能力对脑血管血流动力学的保护关系。我们发现，心肺适应性与较低的颈动脉僵硬和脉压之间存在有益关联，这可能是无可改变危险因素的女性中适应能力与大脑搏动性之间的性别特异性关联的潜在机制。在无危险因素的成年人中，更高的适应性与传导率、脉动阻尼和前向波能量呈有益关联；然而，在有可改变的危险因素的成年人中，关联减弱了。这些数据表明，性别和危险因素可能会改变脑血管对心肺适应性的敏感性。
