Flow-mediated dilation is acutely improved after high-intensity interval exercise

Purpose: Cardiovascular disease is characterized by decreased endothelial function. Chronic exercise training improves endothelial function in individuals with cardiovascular diseases; however, the acute endothelial responses to a single bout of exercise are not consistent in the literature. This study investigated whether a single bout of moderate-intensity endurance exercise (END) and low-volume high-intensity interval exercise (HIT) on a cycle ergometer resulted in similar acute changes in endothelial function. Methods: Ten individuals (66 ± 11 yr) with coronary artery disease (CAD) participated in two exercise sessions (END and HIT). Endothelial-dependent function was assessed using brachial artery flow-mediated dilation (FMD) preexercise and 60 min postexercise. Brachial artery diameters and velocities were determined using Doppler ultrasound before and after a 5 min ischemic period at all time points. Endothelial-independent function was assessed using a 0.4-mg sublingual dose of nitroglycerin. Results: The total work performed was higher in END (166 ± 52 kJ) compared with HIT (93 ± 28 kJ) exercise (P < 0.001). Endothelial-dependent function improved (P = 0.01) after END (absolute FMD preexercise, 0.24 ± 0.18 mm; postexercise, 0.31 ± 0.24 mm) and HIT (absolute FMD preexercise, 0.25 ± 0.13 mm; postexercise, 0.29 ± 0.13 mm), with no differences between exercise conditions. A time effect for FMD normalized to the shear rate area under the curve was also observed (P = 0.02) after END (preexercise, 0.005 ± 0.004; postexercise, 0.010 ± 0.011) and HIT (preexercise, 0.005 ± 0.004; postexercise, 0.009 ± 0.011). Endothelial-independent function responses were unchanged after END and HIT (P > 0.05). Conclusions: HIT and END resulted in similar acute increases in brachial artery endothelial-dependent function in a population with dysfunction at rest, despite the difference in exercise intensities.