title: Intensity of Exercise and Endothelial Function in Healthy Adults
Creators: name: Moxey, Jacquelyn R.
Publisher: name: Old Dominion University
publisherIdentifier: https://ror.org/04zjtrb98
publisherIdentifierScheme: ROR
Year: 2014

description: PURPOSE: To examine the effects of acute bouts of isocaloric exercise at different intensities on endothelial function. The flow-mediated dilation (FMD) responses after the different acute exercise bouts were compared to a control (no exercise) condition. METHODS: Nine healthy subjects completed the study (6 males, 3 females, X ± SD = 24 ± 5 yr, 1.75 ± 0.11 m, 79.2 ± 12.4 kg, 47.9 ± 6.9 mL•kg-1•min-1). Vascular responses were compared under three different conditions- HIT: a bout of high-intensity interval treadmill exercise consisting of ten 1-minute intervals at ~100% VO2max; MOD: moderate-intensity exercise (~50% VO2max) calorically equated to HIT; and CON: a control condition of seated rest equal to the duration of MOD. Flow-mediated dilation of the brachial artery was assessed at baseline (before exercise/control), immediately postexercise/control, l hour post-exercise/control, and 2 hours post-exercise/control. During the FMD test, high-frequency duplex ultrasound measured endothelium-dependent vasodilation of the brachial artery in response to a hyperemic stimulus (5-minute distal forearm occlusion). RESULTS: Repeated measures ANOVA revealed a significant intensity main effect for pre-inflation vessel diameter (p = 0.05). However, mean diameters at baseline (pre-exercise/control) were not different among the conditions, CON, MOD, or HIT (p-values > 0.05). There were weak trends for a higher pre-inflation diameter immediately post-exercise after MOD compared to CON (p = 0.12) and immediately post-exercise after HIT compared to CON (p = 0.12). Pre-inflation diameters tended to remain elevated 1 hour post-exercise after HIT compared to CON (p = 0.07) and 2 hours post-exercise after HIT compared to CON (p = 0.15). Repeated measures ANOV A revealed a significant main effect for intensity (p = 0.05) and a weak trend for a time main effect for FMD responses (p = 0.13). Brachial artery FMD responses were not different among the conditions at baseline (CON: 7.0 ± 2.2%, MOD: 6.0 ± 1.0%, HIT: 6.0 ± 2.0%; p > 0.05). Compared to CON, there was a trend for FMD to be impaired immediately post-exercise after MOD (3.0 ± 0.9%, p = 0.06). FMD was significantly impaired immediately after HIT (1.0 ± 1.3%, p = 0.04). On average, FMD was 4.0% lower compared to CON immediately after MOD (p = 0.06) and 6.0% lower compared to CON immediately after HIT (p = 0.04). FMD remained impaired 1 hour post-exercise after MOD compared to CON (p = 0.03). There were no significant differences in the 2-hr post-exercise FMD responses between the three conditions (p = 0.39). FMD responses in the MOD and HIT conditions were restored to baseline values by 2 hours post-exercise (p > 0.05). CONCLUSION: Compared to the control condition, flow-mediated dilation of the brachial artery was significantly impaired immediately post-exercise after high-intensity interval treadmill exercise and tended to be impaired immediately after moderate-intensity exercise, but was restored to baseline values by 2 hours post-exercise. In healthy young adults, calorically equated acute exercise, regardless of intensity, impaired endothelial function immediately post-exercise and returned to pre-exercise values 2 hours later.