# Does incorporating high intensity interval training in physical education classes improve fitness outcomes of students? A cluster randomized controlled trial

PMID: 36816767
Journal: Preventive medicine reports
Published: 2023 Apr
Authors: Jurić P, Dudley DA, Petocz P

## Question

Does a 12-week, low-dose HIIT program integrated into physical education improve fitness and adiposity outcomes in 10- to 15-year-old students compared with regular PE?

## Summary

This cluster randomized school trial tested adding two 10-minute bodyweight HIIT sessions per week to regular physical education for 12 weeks in Croatian students aged 10-15 years. The intervention improved 20-meter shuttle-run performance, a cardiorespiratory fitness measure, even under intention-to-treat analysis. It did not improve most other Eurofit fitness measures or BMI, and body-fat findings were inconsistent and favored regular PE in the primary analysis.

## Population

- Two hundred seven students aged 10-15 years in grades 5-8 from one Croatian school.
- Sample size: 207
- Age: Intervention mean 12.1 +/- 1.1 years; control mean 12.5 +/- 1.4 years
- Sex: Mixed boys and girls; exact counts not reported in extracted passages
- Fitness level: General schoolchildren of all abilities.
- Health status: No exclusion criteria; family-doctor health status report required.

## Methodology

- Cluster randomized controlled trial with classes allocated to PE plus HIIT or regular PE.
- 12 weeks.
- One school in Zagreb, Croatia, during regular physical education classes.
- Randomized and controlled study design.

## Protocol

- PE-integrated HIIT.
- Modality: Bodyweight circuits and 5 m shuttle sprints.
- Work intervals: 2-minute prep phase plus two 2-minute work phases.
- Recovery: 30-second passive pulse checks between active phases; 2-minute active recovery at end.
- Sets or repetitions: Circuits of 10 repetitions per exercise repeated until time elapsed.
- Intensity: Maximal exertion during working phases; self pulse target at least 13 beats in 6 seconds.
- Session duration: 10 minutes.
- Frequency: 2 sessions per week.
- Program length: 12 weeks.
- Progression: Four example sessions rotated; no formal progression reported.
- Regular PE.
- Modality: School physical education curriculum.
- Intensity: Curriculum-based PE intensity not specified.
- Session duration: 45-minute PE class.
- Frequency: Regular PE schedule.
- Program length: 12 weeks.
- Progression: Curriculum based.

## Outcomes

### 20-meter shuttle run
Status: improved
HIIT improved shuttle-run performance versus regular PE.

p = 0.001, d = 0.31; additional 181.2 m, 95% CI 70.4 to 292.0.

### Intention-to-treat shuttle-run effect
Status: improved
The shuttle-run benefit remained after ITT and missing-data imputation.

ITT p = 0.011, effect 119.6 m; imputation p = 0.003, effect 122.9 m.

### Other Eurofit outcomes
Status: no clear change
No significant intervention effect was found for balance, coordination, speed, flexibility, power, static strength, muscular endurance, or non-reactive agility.

All listed non-shuttle Eurofit effects p > 0.05.

### Body composition
Status: mixed
BMI outcomes did not improve; body fat percentile findings were inconsistent and unexpectedly favored regular PE in the primary model.

Body fat primary p = 0.025 favoring control; ITT p = 0.086; imputation p = 0.11.

## Practical Insights

- A 10-minute bodyweight HIIT block twice weekly can improve schoolchildren's shuttle-run performance.
- Low-dose bodyweight HIIT should not be expected to improve every fitness domain.
- Self pulse checks are feasible but less precise than objective intensity monitoring.

## Limitations

- No objective heart-rate assessment.
- No formal RPE data.
- No diet or outside physical activity data.
- Single-school short-term intervention.
- Body-fat measurement validity concerns.
- Missing outcome data required ITT and imputation analyses.

## Safety And Adherence

- No adverse health outcomes were reported.
- Family doctor health status reports were required.
- Objective heart-rate monitoring was not used.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36816767/) (pubmed)
- [DOI](https://doi.org/10.1016/j.pmedr.2023.102127) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9932703/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.