# Dose-Response Effects of High-Intensity Interval Training on Body Fat, Blood Pressure, and Cardiorespiratory Fitness in Adolescents: A School-Based Randomized Controlled Trial with Responder Analysis PMID: 41283546 Journal: Journal of Functional Morphology and Kinesiology Published: 2025-11-13 Authors: Domaradzki J, Murawska-Ciałowicz E, Popowczak M, Kochan-Jacheć K, Szkudlarek P, Koźlenia D ## Question Do 6, 8, and 10 minute school-based HIIT sessions produce dose-response changes in body fat percentage, systolic and diastolic blood pressure, and VO2max among adolescents, including adolescents previously classified as non-responders? ## Summary This school-based follow-up trial tested whether adolescents who had previously shown little or no response to HIIT could improve after a modified six-week Tabata-style program using 6, 8, or 10 minute HIIT sessions during physical education classes. Body fat percentage and blood pressure did not show clear group-level dose differences, but VO2max improved most consistently with the 10 minute sessions. Bayesian responder analyses suggested substantial individual variability and showed that many prior non-responders became responders after the modified intervention, especially for VO2max and systolic blood pressure. ## Population - Adolescents in the PEER-HEART school project, including prior HIIT non-responders and prior responders used as a control reference. - Sample size: 137 - Age: Group means approximately 16.50 to 16.99 years. - Sex: 66 male and 71 female across E6m, E8m, E10m, CON, and CON-Rs. - Fitness level: School adolescents; VO2max estimated from the Multistage Fitness Test with baseline means varying by sex and group. - Health status: Apparently healthy adolescent school population. ## Methodology - School-based randomized follow-up intervention with three HIIT duration arms, one non-intervention control group, and a stable responder control reference group; Bayesian responder classification and regression analyses were used. - 6 weeks, with assessments before and immediately after the intervention; the follow-up intervention occurred six months after an initial 8 week PE-based intervention. - Physical education classes in a school environment. - Randomized and controlled study design. ## Protocol - 6, 8, or 10 minute Tabata-style school HIIT. - Modality: Bodyweight/calisthenic and plyometric movement pairs. - Work intervals: 20 seconds maximal effort. - Recovery: 10 seconds passive rest. - Sets or repetitions: Repeated 20:10 cycles for 6, 8, or 10 minutes; AMRAP repetitions during each work bout. - Intensity: Maximal effort; heart rate monitored with Polar devices. - Session duration: 10 minute warm-up plus 6, 8, or 10 minute HIIT main set. - Frequency: 2 sessions per week. - Program length: 6 weeks. - Progression: Session duration differed by group; no within-group progression reported for the follow-up intervention. - Non-intervention and stable responder controls. - Modality: Regular physical education exposure only for CON; CON-Rs served as a stable prior-responder reference. - Program length: 6 weeks. ## Outcomes ### VO2max Status: improved VO2max improved over time, with the strongest and most consistent effects reported for the 10 minute HIIT and CON-Rs groups. Time F(1,127)=31.239, p<0.001; duration x time F(4,127)=25.900, p<0.001; duration effect approached significance F(4,127)=2.401, p=0.053. ### Body fat percentage Status: mixed BF% showed a main effect of time but no significant duration effect or duration-by-time interaction; post hoc pre-post comparisons in groups were not significant after correction. Time F(1,127)=11.730, p<0.001; duration F(4,127)=1.161, p=0.331; duration x time F(4,127)=0.645, p=0.632. ### Blood pressure Status: no clear change Group-level analyses did not show significant HIIT duration effects for SBP or DBP over time. SBP time p=0.587 and duration x time p=0.907; DBP time p=0.900 and duration p=0.815. ### Prior non-responder improvement Status: improved Many prior non-responders improved after the modified intervention; final Bayesian responder proportions ranged from 53.2% for VO2max to 68.4% for DBP. McNemar significant for SBP p<0.001 and VO2max p<0.001; GEE prior non-responsive outcome OR=2.46, 95% CI 1.37-4.43, p=0.003. ## Practical Insights - A 20:10 Tabata-style bodyweight format can fit into short school PE windows and still produce measurable aerobic changes. - Extending the main set toward 10 minutes may be useful when the target is VO2max adaptation, but evidence for fat or blood-pressure dose-response was weak. - Responder monitoring matters because some adolescents improve even when group-level effects are modest. ## Limitations - No long-term follow-up. - Maturation stage and BMI were not stratified. - Minor maturation changes across the six-month interval may have contributed to variability. - Some heart-rate data were missing and imputed. - Results are from supervised school PE and may not generalize to unsupervised settings. ## Safety And Adherence - The public extraction did not identify a specific safety or adherence note. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/41283546/) (pubmed) - [DOI](https://doi.org/10.3390/jfmk10040439) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12641850/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.