The Effects of High-Intensity Interval Training and Moderate-Intensity Continuous Training in Sedentary Individuals on Blood Pressure Reactivity

It is accepted that regular exercise improves indices of cardiovascular health including resting blood pressure (BP) and blood pressure reactivity. A commonly cited barrier to exercise is time. High-intensity interval training (HIIT) reduces the time demands of exercise compared to moderate-intensity continuous training (MCT), however the effect of HIIT on resting BP and BP reactivity has not been investigated. Objective: To determine the effect of HIIT on resting BP and BP reactivity compared to MCT. Hypothesis: We hypothesized that 8 weeks of HIIT would result in reductions in resting BP and BP reactivity similar to MCT. Methods: Sedentary adults (5M/11F, age: 29 ± 2) were randomly assigned to either 8 weeks (3 sessions/week) of HIIT or MCT. Participants performed a graded exercise test on a cycle ergometer to establish baseline cardiorespiratory fitness and determine maximal heart rate to set training intensities. Resting systolic and diastolic blood pressure (SBP and DBP, respectively) and mean arterial pressure (MAP) were recorded by an oscillometric device. A Finometer was used to measure beat-to-beat BP during the sympatho-excitatory stressors which included 2 minutes of isometric handgrip exercise (HG) at 40% of maximal voluntary contraction, followed immediately by 3 minutes of post-exercise ischemia (PEI). Cardiorespiratory and blood pressure assessments were repeated post-intervention. Results: SBP decreased post-training in both groups (HIIT: 112 ± 4mmHg to 105 ± 3mmHg, p<0.05; MCT: 119 ± 2 to 115 ± 3, p<0.05). There was a main effect for a decrease in DBP following training (HIIT: 69 ± 3 to 67 ± 3; MCT: 73 ± 3 to 69 ± 2, p<0.05). A main effect was also observed for a decrease in MAP following training (HIIT: 83 ± 3 to 80 ± 3; MCT: 88 ± 2 to 85 ± 2, p<0.01). Analysis of BP reactivity during HG revealed a significant interaction (p<0.05) across all measures. BP reactivity was reduced in the MCT group as measured by ΔSBP (24 ± 3 to 18 ± 3, p<0.05), ΔMAP (23 ± 2 to 17 ± 2, p<0.01) and ΔDBP (23 ± 2 to 16 ± 2, p<0.01). No changes in BP reactivity were observed in the HIIT group. Analysis of BP during PEI revealed a significant interaction (p<0.05) across all measures. HIIT augmented ΔSBP (14 ± 3 to 20 ± 4, p<0.05) during PEI and a trend was observed for ΔMAP (p=0.056) whereas MCT resulted in no differences pre to post intervention. Conclusion: These data suggest that both HIIT and MCT interventions can improve resting BP in sedentary individuals; however, there appears to be a divergent effect of HIIT and MCT on BP reactivity in response to HG suggesting a heightened metaboreflex following HIIT which requires further study. NIH Grant P20GM113125 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.