Acute Brachial Artery Responses to Endurance and High-Intensity Interval Exercise in Young Healthy Males

Abstract

<p><strong>Purpose: </strong>Habitual aerobic exercise improves vascular function; however, the acute vascular response to exercise is poorly understood. The present investigation compared the time course of acute changes in vascular function following two different types of aerobic exercise. <strong>Methods: </strong>Ten untrained males (23 ± 2 yrs) completed one bout of sustained moderate-intensity cycling (END) (30 mins at 55% peak power) or high-intensity interval (HIT) cycling (10 one-minute intervals at 80% peak power) on different days. Endothelium-dependent dilation was assessed by brachial artery flow-mediated dilation (baFMD) at baseline, immediately post-exercise, 1 hour post-exercise and 24 hours post-exercise. Endothelium-independent dilation was assessed via nitroglycerin (NTG) at all time points, except 1 hour post-exercise. <strong>Results:</strong> baFMD values were not significantly different between END and HIT at any time point. Immediately post-exercise baFMD values were unchanged from baseline. 1 Hour post-exercise, relative (p £ 0.001) and absolute (p £ 0.05) baFMD values were attenuated compared to all other time points for both HIT (%FMD baseline: 5.9 ± 2.3%; 1 hour post-exercise: 2.5 ± 1.5%) and END (%FMD baseline: 6.8 ± 2.4%; 1 hour post-exercise: 2.6 ± 1.9%). Relative (p £ 0.05) and absolute (p £ 0.05) NTG responses were attenuated immediately post-exercise compared to baseline for both HIT (%NTG baseline: 18.8 ± 4.4%; immediately post-exercise: 12.3 ± 3.1%) and END (%NTG baseline: 18.3 ± 3.1%; immediately post-exercise: 10.9 ± 4.9%). <strong>Conclusions: </strong>Immediately post-exercise, endothelium-dependent dilation is maintained; but reduced 1 hour following exercise cessation. Similar acute vascular responses are found following HIT and END.</p>