Exaggerated vasopressor response to exercise and cerebral blood flow velocity

Point/counterpoint: Arterial blood pressure response to exercise does relate to exercise-induced improvement in cognitive function

Exercise is a beneficial intervention to prevent cognitive dysfunction. However, an optimal exercise prescription for preventing dementia has not been established because the physiological mechanism(s) of exercise-induced improvements in cognitive function remains unclear. Interestingly, our recent study demonstrated that individuals with a higher exercise pressor response exhibit less exercise-induced cognitive improvement, suggesting that individual differences in cardiovascular responses to exercise or its associated physiological factors, may be related to exercise-induced alterations in cognitive function. Therefore, consideration of individual cardiovascular responses is warranted to develop appropriate exercise prescriptions for a given individual to prevent cognitive dysfunction.

Cerebrovascular responses to submaximal exercise in women with COPD

BACKGROUND

COPD patients have decreased physical fitness, and have an increased risk of vascular disease. In the general population, fitness is positively associated with resting cerebral blood flow velocity, however, little is known about the cerebrovascular response during exercise particularly in COPD patients. We hypothesized that COPD patients would have lower cerebral blood flow during exercise secondary to decreased physical fitness and underlying vascular disease.

METHODS

Cardiopulmonary exercise testing was conducted in 11 women with GOLD stage I-II COPD, and 11 healthy controls to assess fitness. Cerebro- and cardio-vascular responses were compared between groups during two steady-state exercise tests (50% peak O2 consumption and 30 W). The main outcome variable was peak middle cerebral artery blood flow velocity (VP) during exercise using transcranial Doppler ultrasonography.

RESULTS

Physical fitness was decreased in COPD patients. VP was comparable between COPD and controls (25 ± 22% versus 15 ± 13%, respectively; P > 0.05) when exercising at the same relative intensity, despite patients having higher blood pressure and greater arterial desaturation. However, VP was elevated in COPD (31 ± 26% versus 13 ± 10%; P ≤ 0.05) when exercising at the same workload as controls.

CONCLUSIONS

Our results are contradictory to our a-priori hypothesis, suggesting that during matched intensity exercise, cerebral blood flow velocity is similar between COPD and controls. However, exercise at a modestly greater workload imposes a large physical demand to COPD patients, resulting in increased CBF compared to controls. Normal activities of daily living may therefore impose a large cerebrovascular demand in COPD patients, consequently reducing their cerebrovascular reserve capacity.

Effects of dietary nitrates on systemic and cerebrovascular hemodynamics

Cerebral blood flow dysregulation is often associated with hypertension. We hypothesized that a beetroot juice (BRJ) treatment could decrease blood pressure and cerebrovascular resistance (CVR). We subjected 12 healthy females to control and BRJ treatments. Cerebrovascular resistance index (CVRI), systolic blood pressure (SBP), total vascular resistance (TVR), and the heart rate-systolic pressure product (RPP) measured at rest and at two exercise workloads were lower after the BRJ treatment. CVRI, SBP, and RPP were lower without a lower TVR at the highest exercise level. These findings suggest improved systemic and cerebral hemodynamics that could translate into a dietary treatment for hypertension.