Association between exercise hemodynamics and changes in local vascular function following acute exercise.

Skeletal muscle contractions are associated with physical stimuli that act upon muscle vasculature, including increased shear stress and blood pressure. It is unclear if acute dynamic exercise alters local vascular function. The purpose of this study was to examine the role of exercise hemodynamics on the effects of acute exercise on vascular function, as evaluated by brachial artery flow-mediated dilation (FMD). Healthy individuals (n = 14; age, 18-34 years) performed 30 min of handgrip exercise at fast and slow contractions. Blood pressure during exercise was measured using a Vasotrac system (Medwave Inc.), while shear rate during exercise and FMD at rest and after 30 min of recovery from exercise were measured in the brachial artery of the active arm using Doppler ultrasound. Estimated contractile work was correlated with blood pressure (r = 0.61, p < 0.01) and retrograde shear rate (r = -0.78, p < 0.01). As a result, blood pressure was higher (p < 0.05) and oscillatory shear index was lower (p < 0.05) during slow as compared with fast contractions. On average, FMD was unchanged following fast contractions (5.4 ± 3.4%dilation to 6.1 ± 3.8%dilation; p = 0.19), but significantly reduced following slow contractions (6.9 ± 4.2%dilation to 3.6 ± 2.5%dilation; p = 0.01). Within slow contractions, subgroup analysis revealed blood pressure to associate with the change in FMD; such that individuals with mean blood pressure >100 mm Hg (range, 102-139 mm Hg) during exercise had larger decreases in FMD than individuals with lower exercise blood pressure. These results indicate that impaired local vascular function following acute exercise with high contractile activity is associated with blood pressure stimuli in healthy individuals.