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

Q: What are the key findings of this study?

In adolescents previously non-responsive to HIIT, individualized dose modifications induced meaningful adaptations, with the number of prior non-responsive outcomes strongly predicting the likelihood of future improvement (OR 2.46).

Q: What is the clinical evidence from this study?

Study design: RCT. Population: Healthy adolescents (prior non-responders to exercise) (n=137). Intervention: High-intensity interval training (HIIT) vs. Control group (regular physical education). Primary outcome: Likelihood of improving in previously non-responsive outcomes (becoming a responder) (OR 2.46, 95% CI 1.26-4.76, p=0.008).

Q: What does this research mean for the field?

School-based high-intensity interval training (HIIT) improves cardiorespiratory and body composition outcomes across 6, 8, and 10-minute sessions, and modifying the intervention can successfully induce improvements even in previously non-responsive adolescents. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Jarosław Domaradzki; Eugenia Murawska‐Ciałowicz; Marek Popowczak; Katarzyna Kochan; Paweł Szkudlarek; Dawid Koźlenia

doi:10.3390/jfmk10040439

November 13, 2025Journal of Functional Morphology and KinesiologyOpen Access

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

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Key result

Individualized HIIT dose modifications yield ~2.5-fold higher odds of response in previously non-responsive adolescents.

OR 2.46
95% CI 1.26-4.76
P=0.008
n=137

Figures

Why the study?

HIIT improves body composition and cardiorespiratory fitness, but individual variability in responsiveness remains a challenge.

Does modifying the session duration of school-based high-intensity interval training improve body fat percentage, blood pressure, and cardiorespiratory fitness in previously non-responsive adolescents?

Study Design

Type

RCT (n=137)

Randomization

Randomly assigned based on baseline ID codes

Structured PICO

Does modifying the session duration of school-based high-intensity interval training improve body fat percentage, blood pressure, and cardiorespiratory fitness in previously non-responsive adolescents?

P

Population

137 adolescents who previously showed no improvements from an initial HIIT program, re-randomized to 6, 8, or 10-minute HIIT sessions or control for 6 weeks.

I

Intervention

High-intensity interval training (HIIT) using a Tabata protocol (20s maximal effort, 10s passive rest), performed twice weekly during physical education classes for 6 weeks. Three session duration variants were tested: 6 minutes, 8 minutes, and 10 minutes.

C

Comparator

Two control groups (CON for prior non-responders, CON-Rs for prior responders) that participated only in regular physical education classes without structured high-intensity training.

O

Outcome

Changes in body fat percentage (BF%), systolic blood pressure (SBP), diastolic blood pressure (DBP), and cardiorespiratory fitness (maximal oxygen uptake, VO2max) measured pre- and post-intervention.surrogate

Main Result

Odds Ratio: 2.46 (95% CI 1.26–4.76)

p-value: p=0.008

Adjusting the duration of school-based high-intensity interval training sessions can elicit positive cardiovascular and fitness adaptations even in adolescents who previously failed to respond to a standard HIIT protocol.

Limitations

Reliance on group-derived data may not capture individual physiological adaptations, such as hormonal responses.
Did not stratify participants by maturation stage or BMI, which are important confounders influencing training responsiveness in adolescents.
Absence of a long-term follow-up limits the understanding of whether the improvements were sustained over time.

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Implication

Supports tailoring HIIT duration for non-responsive adolescents; extends evidence for individualized dosing in youth.

Abstract

Background: High-intensity interval training (HIIT) is effective for improving body composition and cardiorespiratory fitness, but individual variability in responsiveness remains a challenge. This study examined the dose–response effects of three HIIT session durations (6, 8, and 10 min) and whether previously non-responsive adolescents could benefit from a modified program. Methods: A total of 137 adolescents completed one of three school-based HIIT interventions. Body fat percentage (BF%), systolic and diastolic blood pressure, and maximal oxygen uptake (VO2max) were assessed before and after the intervention. Responders and non-responders were classified using a Bayesian approach. Statistical analyses included ANOVA, McNemar’s test, logistic regression, and generalized estimating equations. Results: All protocols improved outcomes, with the 10 min sessions producing the most consistent VO2max gains. No significant differences were observed for BF% or blood pressure. Individual analysis showed that more than half of the participants responded positively to training, depending on the outcome. Among prior non-responders, 70–100% showed improvements after the modified intervention. The number of previously non-responsive outcomes strongly predicted improvement (Odds Ratio > 2.4, p < 0.01). Conclusions: School-based HIIT can induce meaningful adaptations even in previously non-responsive adolescents. Individualized monitoring and adjustment of training dose may optimize responsiveness and support health promotion in youth.

Discussion

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Cite This Study

Domaradzki et al. (2025) conducted an RCT in Healthy adolescents (prior non-responders to exercise) (n=137). High-intensity interval training (HIIT) vs. Control group (regular physical education) was evaluated on Likelihood of improving in previously non-responsive outcomes (becoming a responder) (OR 2.46, 95% CI 1.26-4.76, p=0.008). In adolescents previously non-responsive to HIIT, individualized dose modifications induced meaningful adaptations, with the number of prior non-responsive outcomes strongly predicting the likelihood of future improvement (OR 2.46).

synapsesocial.com/papers/6a218f9c96850e9b858b9318 https://doi.org/10.3390/jfmk10040439

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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

Figures

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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

Figures

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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