post-exercise hypotension; ambulatory blood pressure monitoring; physical exercise. 

Objective: To investigate the effect of a single session of low-volume high intensity interval exercise (HIIE) on ambulatory blood pressure (BP) in normotensives. Methods: Twenty-one normotensive males (23.6 ± 3.6 years, 23.5 ± 2.3 kg/m2, resting BP 111.1 ± 6.4 / 62.4 ± 6.1) performed: (i) maximum incremental test; (ii) HIIE and control sessions in a randomized order. The HIIE consisted of 10 x 60s bouts at 100% of maximal treadmill velocity interspersed by 60s of passive recovery. Paired sample t-test was used to compare systolic and diastolic BP between the control and the HIIE sessions. A two-way ANOVA (condition vs. time) was used to compare the ambulatory hourly BP following the control and the HIIE sessions. Results: Systolic (-2.8 ± 3.7 mmHg) and diastolic BP (-1.7 ± 3.5 mmHg) were lower in 20h and awake periods (systolic -3.2 ± 3.7 mmHg; diastolic BP -1.8 ± 3.9 mmHg) following the HIIE session compared to the control session (p<0.05). There were no differences in systolic and diastolic BP during the asleep period (p>0.05). Two-way ANOVA revealed that systolic BP was lower in the first five hours following the HIIE session compared to the control session [minimum delta: -3.2 mmHg; maximum delta: -4.8 mmHg (p<0.05)]. Conclusions: A single session of low-volume HIIE reduces ambulatory BP in normotensives. The greater magnitude of hypotension during the first five hours post-exercise explains the BP reduction in 20h and awake periods.