# Vascular-endothelial adaptations following low and high volumes of high-intensity interval training in patients after myocardial infarction PMID: 39380195 Journal: Therapeutic advances in cardiovascular disease Published: 2024 Jan-Dec Authors: Aispuru-Lanche R, Jayo-Montoya JA, Maldonado-Martín S ## Question Is low-volume HIIT with less than 10 minutes at high intensity per session sufficient to improve endothelial function, oxidative stress, and carotid intima-media thickness in patients after acute myocardial infarction, and how does it compare with higher-volume HIIT and unsupervised physical activity recommendations? ## Summary This randomized clinical trial compared low-volume HIIT, high-volume HIIT, and unsupervised physical activity recommendations in 80 patients after acute myocardial infarction. Both supervised HIIT programs improved brachial artery flow-mediated dilation, lowered oxidized LDL, and slightly reduced carotid intima-media thickness compared with the control group. Low-volume HIIT used only 8 minutes per session in the high-intensity range and still produced favorable vascular-endothelial changes. ## Population - 80 clinically stable adults 1-6 months after acute myocardial infarction with preserved systolic function, randomized to attention control, low-volume HIIT, or high-volume HIIT. - Sample size: 80 - Age: 58.4 +/- 8.3 years - Sex: 66 men (82.5%), 14 women (17.5%) - Fitness level: Mean VO2peak 23.5 +/- 6.6 ml/kg/min; MET 7.0 +/- 2.1. - Health status: Post-AMI, clinically stable, preserved ejection fraction; high prevalence of hypertension, dyslipidemia, diabetes, and statin use. ## Methodology - Randomized clinical trial with three parallel groups and pre-post measurements. - 16 weeks - Cardiac Rehabilitation Facility in Santiago Apostol Hospital's Cardiology Department, Miranda de Ebro, Burgos, Spain. - Randomized and controlled study design. ## Protocol - Low- and high-volume supervised HIIT after AMI. - Modality: Treadmill one day and cycle ergometer one day each week. - Work intervals: Treadmill 4 minutes at R3; cycle 30 seconds at R3. - Recovery: Treadmill 3 minutes at R2; cycle 60 seconds at R2. - Sets or repetitions: LV-HIIT 8 minutes total R3; HV-HIIT 16 minutes total R3. - Intensity: R3 from VT2 to maximum HR, alternating with R2 between VT1 and VT2; controlled by HR and Borg RPE. - Session duration: LV-HIIT 20 minutes; HV-HIIT 20-40 minutes. - Frequency: 2 sessions/week on non-consecutive days. - Program length: 16 weeks. - Progression: HV-HIIT total volume gradually increased from 20 to 40 minutes; treadmill speed/incline and cycling watts adjusted individually. - Attention control physical activity recommendations. - Modality: Unsupervised moderate-intensity aerobic activity such as walking, jogging, cycling, or swimming. - Intensity: Moderate intensity with individualized HR domains from ergospirometry for self-control. - Session duration: At least 30 minutes. - Frequency: 5-7 days/week. - Program length: 16 weeks. ## Outcomes ### FMD Status: improved FMD increased in both exercise groups compared with control: LV-HIIT had a 1.6-fold increase and HV-HIIT had a 1.9-fold increase. LV-HIIT +58.8 +/- 8.5%; HV-HIIT +94.1 +/- 9.7%; ANOVA p < 0.001. ### Endothelial dysfunction prevalence Status: improved Endothelial dysfunction prevalence decreased in both HIIT groups, from 92.9% to 60.7% in LV-HIIT and from 85.7% to 57.1% in HV-HIIT. ANOVA p = 0.0018 for reduction in endothelial dysfunction. ### Oxidized LDL Status: improved ox-LDL decreased in both HIIT groups compared with no variation in control, with a larger reduction in HV-HIIT. LV-HIIT -5.2 +/- 2.2%; HV-HIIT -8.9 +/- 3.7%; ANOVA p < 0.001. Correlation between delta FMD and delta ox-LDL: LV-HIIT r = -0.376, p = 0.047; HV-HIIT r = -0.490, p = 0.008. ### cIMT Status: improved cIMT decreased slightly in both HIIT groups compared with control, without meaningful difference between low and high volume. LV-HIIT -3.0 +/- 1.1%, p = 0.0389; HV-HIIT -3.2 +/- 1.2%, p = 0.0305; ANOVA p = 0.019; low vs high p = 0.467. ### Safety Status: no clear change No relevant adverse events were reported, and no participant dropped out. ## Practical Insights - In supervised cardiac rehabilitation after AMI, less than 10 minutes of accumulated high-intensity work per session may be sufficient for favorable vascular-endothelial adaptations. - Clinical HIIT protocols should report both total session duration and accumulated high-intensity time. - Cardiac-risk HIIT translation requires screening, clinical supervision, individualized thresholds, and adverse-event monitoring. ## Limitations - Small sample size. - Uneven gender distribution with 82.5% men. - Sixteen-week duration may be short for atherosclerotic progression outcomes. - Atherosclerosis was only evaluated in carotid arteries. - Only one oxidative stress biomarker, ox-LDL, was used. - Supplemental protocol details existed but were not used for this extraction. ## Safety And Adherence - No relevant adverse events were reported throughout the intervention and supervised training sessions. - All participants completed the 16-week training protocol. - Patients were screened for clinical stability, preserved systolic function, and absence of high-risk exercise contraindications. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/39380195/) (pubmed) - [DOI](https://doi.org/10.1177/17539447241286036) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11483797/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.