Acute Exercise Improves Endothelial Function Despite Increasing Vascular Resistance During Stress in Smokers and Non-smokers

Abstract

Endothelial dysfunction, measured by flow mediated dilation (FMD), and hyper-reactivity to neurovascular challenges are two potential mechanisms by which cigarette smoking can be harmful to the vasculature. It has been suggested that acute exercise may improve endothelial function and attenuate cardiovascular reactivity to neurovascular stressors, but we could not locate studies of female smokers that examined FMD after neurovascular stress. PURPOSE: To determine the effect of an acute bout of moderate-intensity cycling exercise on FMD and cardiovascular responses during neurovascular stress among sedentary female smokers and non-smokers. METHODS: FMD was determined by brachial arterial diameter, arterial velocity and blood flow measured by Doppler ultrasonography after forearm occlusion. Those measures and beat-to-beat finger blood pressure (BP) and heart rate (HR) were also assessed in response to 2 min of forehead cold and 4 min of the Stroop Color-Word conflict test (CWT). Individuals participated in two counterbalanced conditions: 30 minutes of either passive rest or cycling exercise (∼50% VO2peak). FMD was tested 8 min after stress. RESULTS: Baseline FMD and stress responses were not different between smokers and non-smokers. Compared to passive rest, exercise increased FMD (7 ± 2% vs. 5 ± 2%) and resting HR; arterial velocity; and blood flow, and decreased resting SBP in both groups. During the Stroop CWT, arterial velocity (-9 ± 8 vs. 2 ± 2 cm/s) and blood flow (-53 ± 58 vs. 19 ± 38 ml/min) responses were reduced after exercise compared to passive rest in smokers and non-smokers. Similarly, during forehead cold, reductions in arterial velocity (-19 ± 11 vs. -4.5 ± 4.5 cm/s) and blood flow (-107 ± 74% vs. -25 ± 30 ml/min) responses were augmented after exercise compared to passive rest. CONCLUSIONS: Acute cycling exercise improved endothelial function among female smokers and non-smokers despite increasing vascular resistance and reducing limb blood flow during both dilatory and constrictive neurovascular stress in the presence of post-exercise hypotension.