# Effects of school-based high-intensity interval training on body composition, cardiorespiratory fitness and cardiometabolic markers in adolescent boys with obesity: a randomized controlled trial

PMID: 35232402
Journal: BMC pediatrics
Published: 2022 Mar 1
Authors: Meng C, Yucheng T, Shu L, Yu Z

## Question

Can school-based running HIIT improve body composition, cardiorespiratory fitness, and cardiometabolic markers in boys with obesity compared with MICT and control?

## Summary

This randomized school-based trial compared 12 weeks of short running HIIT, 30-minute moderate continuous running, and usual behavior in Chinese boys with obesity. HIIT and MICT both improved BMI, fat mass, cardiorespiratory fitness, and HOMA-IR, but HIIT produced a larger VO2peak increase and reduced visceral adipose tissue and LDL. The HIIT sessions required far less weekly training time than MICT.

## Population

- Adolescent boys with obesity.
- Sample size: 45
- Age: 11.2 +/- 0.7 years.
- Sex: Boys only.
- Fitness level: Self-reported less than 2 hours physical activity per week.
- Health status: BMI at or above 95th percentile; Tanner stage 1-3; excluded medications or conditions such as cardiac abnormalities, hypertension, diabetes, orthopedic, neuromuscular, or neurological disorders and any contraindication to physical activity.

## Methodology

- Parallel-group randomized controlled trial with HIIT, MICT, and non-exercising control groups.
- 12 weeks.
- Experimental School in China; outdoor track training during school activity class time, with hospital/lab testing.
- Randomized and controlled study design.

## Protocol

- School-based running HIIT.
- Modality: Outdoor track running.
- Work intervals: 15 seconds at 90-100% MAS.
- Recovery: 15 seconds at 50% MAS; 3-minute rest between two sets.
- Sets or repetitions: 2 sets of 8 bouts.
- Intensity: 90% MAS weeks 1-4, 95% MAS weeks 5-8, 100% MAS weeks 9-12; about 80-90% HRmax.
- Session duration: 11-minute HIIT block, plus 5-minute warm-up and cooldown.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: MAS-based intensity increased every 4 weeks and speed recalibrated after weeks 4 and 8.
- MICT and control.
- Modality: Outdoor continuous running; usual behavior control.
- Work intervals: 30-minute continuous run for MICT.
- Sets or repetitions: One continuous run.
- Intensity: 60% MAS weeks 1-4, 65% weeks 5-8, 70% weeks 9-12.
- Session duration: 30 minutes for MICT plus warm-up/cooldown context.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: MICT intensity increased every 4 weeks; control maintained normal routine.

## Outcomes

### Body composition
Status: improved
BMI and fat mass decreased in both HIIT and MICT; visceral adipose tissue decreased significantly in HIIT, while body fat percentage decreased in MICT.

BMI: HIIT -1.8 kg/m2 and MICT -1.2 kg/m2, p<0.01; FM: HIIT -1.6 kg p<0.05, MICT -3.7 kg p<0.01; VAT HIIT -53 g vs -17 g, p<0.01.

### VO2peak
Status: improved
VO2peak improved in both exercise groups, with a significantly larger increase in HIIT.

HIIT +6.0 to 6.1 mL/kg/min vs MICT +3.8 mL/kg/min, p<0.01.

### HOMA-IR
Status: improved
HOMA-IR improved in both HIIT and MICT, with no significant difference between exercise groups.

HIIT -27.3% and MICT -28.6%, p<0.05.

### LDL cholesterol
Status: improved
LDL decreased only in the HIIT group.

LDL -17.2%, p<0.05.

### Other cardiometabolic markers
Status: mixed
No significant changes were found in other cardiometabolic markers; DBP did not significantly change within intervention groups but was lower than control post-intervention.

Authors report no significant change in other cardiometabolic markers.

## Practical Insights

- A very short MAS-paced 15/15 running protocol can improve fitness in boys with obesity.
- Compared with MICT, HIIT achieved similar or better outcomes with much less session time.
- Some participants initially struggled to hit prescribed distances, so pacing should be adaptive.

## Limitations

- Small sample and boys only.
- Some students refused participation, creating potential selection bias.
- No daily physical activity diary/accelerometer for all participants.
- Running intensity on track was difficult to measure and monitor precisely.
- Maturation during intervention may have influenced outcomes.
- Adverse events were not clearly reported.

## Safety And Adherence

- Adverse events were not explicitly reported in the extracted full text.
- Participants with medical conditions or contraindications were excluded.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/35232402/) (pubmed)
- [DOI](https://doi.org/10.1186/s12887-021-03079-z) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8886768/) (full text)

## Agent Guidance

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