High-Intensity Exercise Enhances Conduit Artery Vascular Function in Older Adults

Abstract

Purpose: Modulation of vascular function follows an exercise intensity- dependent pattern in young adults. This study aimed to investigate the potential intensity-dependent effects of an acute bout of exercise on conduit and resistance artery function in healthy older adults. Methods: Eleven healthy older adults (five males/six females, 66 T 1 yr) completed 30 min of recumbent cycling at 50%-55% (low intensity) and 75%-80% (high intensity) of their age-predicted HRmax on two separate study visits. Doppler ultrasound measures of brachial artery flow-mediated dilation (FMD) and reactive hyperemia were taken at baseline, 10 min postexercise, and 1 h postexercise. In addition, cardiovascular hemodynamics and brachial shear rate were measured every 5min during exercise. Results: Brachial artery FMD was enhanced 10 min after high-intensity exercise (4.8% T 0.2% to 9.1% T 0.3%, P G 0.01), but not low-intensity (4.7% T 0.2% to 6.2% T 0.3%, P = 0.54) exercise. Peak and total (area under the curve) blood flow during reactive hyperemia (measures of resistance artery function) were enhanced 10 min postexercise for both intensities (peak lowintensity, 372 T 31 to 444 T 37 mLIminj1; peak high intensity, 391 T 30 to 455 T 28 mLIminj1; total lowintensity, 142 T 16 to 205 T 20 mL; total high intensity, 158 T 14 to 240 T 25 mL; main effect of time for both, P G 0.05). However, the magnitude of change in peak and the total blood flow were not different between exercise intensities (interaction effect; P = 0.56 and P = 0.97, respectively). Independent of exercise intensity, FMD returned to baseline 1 h after exercise (high, 5.9% T 0.3%; low, 5.1% T 0.1%; both P 9 0.05). Conclusion: Our data indicate that highintensity exercise acutely enhances conduit artery function in healthy older adults. In addition, an acute bout of exercise enhances resistance artery function independent of intensity.