# Acute effects of high-intensity interval exercise and moderate-intensity continuous training on arterial stiffness and endothelial function in hypertension: A crossover trial PMID: 41131037 Journal: Scientific Reports Published: 2025-10-23 Authors: Feng W, Yu WL, Zhao Z, Guo YD, Zhou XJ, Zhai KQ, Liu X, Yan ZW ## Question What are the acute effects of HIIT compared with energy-matched MICT on endothelial function, arterial stiffness, and blood-pressure-related hemodynamics in adults with essential hypertension? ## Summary In 30 adults with essential hypertension, a single treadmill HIIT session and an energy-matched moderate continuous treadmill session were compared in a crossover sequence. The primary endothelial outcome, flow-mediated dilation, did not improve after either session. Moderate continuous exercise produced more favorable acute vascular findings than HIIT, including transient vasodilation and lower brachial-ankle pulse wave velocity lasting to 24 hours, while HIIT produced a larger immediate systolic blood pressure, pulse pressure, and heart rate response. ## Population - Thirty middle-aged adults with essential hypertension, 16 male and 14 female, with no regular exercise habits in the prior 3 months. - Sample size: 30 - Age: Median 53 years (IQR 52-55); eligible age 50-65 years. - Sex: 16 males, 14 females. - Fitness level: Inactive recently; mean VO2peak 27.32 +/- 4.52 mL/kg/min. - Health status: Essential hypertension with SBP 140-179 mmHg and DBP 90-109 mmHg; major comorbidities excluded. ## Methodology - Acute crossover trial comparing one HIIT session with one energy-matched MICT session after a 1-week washout. - Two acute exercise sessions separated by a 1-week washout; outcomes measured immediately, 5 minutes, and 24 hours postexercise. - Treadmill exercise with blinded outcome measurement; professional medical personnel present throughout. - Controlled study design. ## Protocol - HIIT treadmill session. - Modality: Treadmill running with walking warm-up and cool-down. - Work intervals: 10 x 1 minute at 85-95% HRpeak, approximately 90% VO2peak. - Recovery: 10 x 2 minutes at 60-70% HRpeak. - Sets or repetitions: 10 intervals. - Intensity: Hard intervals 85-95% HRpeak with Borg RPE target 16-17. - Session duration: 40 minutes including warm-up and cool-down. - Frequency: Single acute session. - Program length: Acute crossover session. - Progression: No progression; treadmill speed adjusted to prescribed intensity. - MICT treadmill session. - Modality: Treadmill running with walking warm-up and cool-down. - Work intervals: 32 minutes continuous moderate exercise. - Sets or repetitions: 1 continuous bout. - Intensity: 65-75% HRpeak during continuous phase; 50-60% HRpeak during warm-up and cool-down. - Session duration: 42 minutes including warm-up and cool-down. - Frequency: Single acute session. - Program length: Acute crossover session. - Progression: No progression; treadmill speed adjusted to prescribed intensity. ## Outcomes ### Flow-mediated dilation Status: no clear change Neither HIIT nor MICT significantly changed FMD, and there were no significant differences between trials. Time P=0.457; trial P=0.536; time x trial P=0.081. ### Arterial diameter Status: improved MICT increased arterial basal internal diameter at 5 minutes and peak diameter immediately postexercise, while HIIT did not significantly change these measures. Basal diameter time x trial P=0.028; peak diameter time x trial P=0.019. ### Blood pressure and pulse pressure Status: mixed Both protocols increased SBP immediately, but MICT reduced SBP by 5 minutes whereas HIIT produced a larger immediate SBP and pulse pressure surge. SBP time x trial P<0.001; PP time x trial P=0.008. ### Brachial-ankle pulse wave velocity Status: improved MICT reduced baPWV immediately and remained below baseline at 24 hours; HIIT did not significantly change baPWV. baPWV time x trial P<0.001. ### Ankle-brachial index Status: no clear change ABI did not significantly change after either intervention. Time P=0.511; trial P=0.413; time x trial P=0.387. ## Practical Insights - For hypertensive users, HIIT may need more conservative safety framing than moderate continuous exercise because this protocol produced larger immediate SBP, pulse pressure, and HR responses. - A 1-minute hard / 2-minute active recovery treadmill interval structure is reproducible, but its acute vascular results were not favorable relative to MICT in this population. - Moderate continuous exercise may be a better acute option when the goal is immediate vascular stiffness reduction or hemodynamic stabilization. ## Limitations - Acute-only study; does not establish chronic training adaptations. - Small clinical sample. - Condition order appears fixed rather than randomized. - High-risk comorbid groups were excluded. - Adherence, enjoyment, and participant experience were not deeply assessed. - Medication discontinuation around testing limits real-world translation. ## Safety And Adherence - Professional medical personnel were present throughout the study to respond to emergencies. - Adverse events during exercise were recorded, but no specific adverse events were reported in the article text. - HIIT produced greater immediate hemodynamic load than MICT in this hypertensive sample. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/41131037/) (pubmed) - [DOI](https://doi.org/10.1038/s41598-025-21045-y) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12550041/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.