# Asthma and high-intensity interval training have no effect on clustered cardiometabolic risk or arterial stiffness in adolescents

PMID: 33778908
Journal: European Journal of Applied Physiology
Published: 2021
Authors: McNarry MA, Lester L, Ellins EA, Halcox JP, Davies G, Winn CON, Mackintosh KA

## Question

Do asthma status and a 6-month school-based HIIT intervention affect clustered cardiometabolic risk factors or arterial stiffness in adolescents?

## Summary

In a subsample of adolescents from a school-based HIIT trial, 6 months of game- and circuit-based HIIT did not change clustered cardiometabolic risk or arterial stiffness measures. No adverse events were reported, but the authors noted poor adherence as a key limitation.

## Population

- Adolescents with and without asthma who completed all four assessment timepoints in the X4A trial
- Sample size: 65
- Age: 13.5 +/- 0.9 years
- Sex: 37 boys, 28 girls
- Fitness level: School adolescents; not athlete-selected
- Health status: 33 adolescents had mostly mild, controlled asthma; unstable asthma exacerbation in the prior 4 weeks was excluded

## Methodology

- Randomized school-based intervention subsample analysis
- 6 months plus 3-month follow-up
- School-based HIIT sessions
- Randomized and controlled study design.

## Protocol

- School-based HIIT.
- Modality: Circuits and games-based activities.
- Work intervals: 10-30 seconds, progressed over the intervention.
- Recovery: Matched rest intervals.
- Sets or repetitions: Not fully specified; 30-minute sessions using 1:1 exercise-to-rest.
- Intensity: Intended >90% HRmax.
- Session duration: 30 minutes.
- Frequency: 3 sessions per week.
- Program length: 6 months.
- Progression: Bout duration progressed from 10 to 30 seconds.
- Control.
- Modality: Routine activities.
- Work intervals: Not applicable.
- Recovery: Not applicable.
- Sets or repetitions: Not applicable.
- Intensity: Usual activity.
- Session duration: Not applicable.
- Frequency: Not applicable.
- Program length: 6 months.
- Progression: No intervention progression.

## Outcomes

### Risk factors
Status: no clear change
The HIIT intervention did not affect clustered cardiometabolic risk factors.

No intervention effect or interaction was found for any PCA-derived factor at any timepoint.

### Arterial stiffness
Status: no clear change
Arterial stiffness outcomes were not improved by HIIT.

No intervention effect was found for arterial stiffness-related PCA factors; PWV and AIx were interpreted as distinct constructs.

### Individual markers
Status: mixed
Some individual markers such as LDL, diastolic blood pressure, and SEVR showed isolated intervention effects.

Intervention effects were reported for LDL at mid-intervention p=0.019, DBP at mid-intervention p=0.029, and SEVR post-intervention p=0.006.

### Safety
Status: no clear change
No adverse events were reported in either group.

Adverse events were reported narratively as none in both intervention and control groups.

## Practical Insights

- School HIIT did not change clustered cardiometabolic or arterial-stiffness measures in this adolescent subsample.
- Mild, controlled asthma was not associated with worse arterial stiffness in this cohort.
- Poor adherence can limit the impact of school-based HIIT even when the program is ecologically realistic.

## Limitations

- Subsample restricted to participants with all four timepoints.
- Mostly Caucasian urban adolescents.
- Asthma was mostly mild/well controlled and partly self-reported.
- Adiposity was measured indirectly.
- Poor adherence limited intervention influence.

## Safety And Adherence

- No adverse events were reported in either group. Adolescents with an unstable asthma exacerbation in the previous 4 weeks were excluded.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/33778908/) (pubmed)
- [DOI](https://doi.org/10.1007/s00421-020-04590-4) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8192411/) (full text)

## Agent Guidance

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