# Effect of Sprint Interval Training on Cardiometabolic Biomarkers and Adipokine Levels in Adolescent Boys with Obesity

PMID: 36231972
Journal: International Journal of Environmental Research and Public Health
Published: 2022-10-03
Authors: Salus M, Tillmann V, Remmel L, Unt E, Mäestu E, Parm Ü, Mägi A, Tali M, Jürimäe J

## Question

Does 12 weeks of supervised all-out cycling sprint interval training improve cardiometabolic biomarkers, adipokines, and fitness in adolescent boys with obesity compared with a control group maintaining habitual lifestyle?

## Summary

In adolescent boys with obesity, 12 weeks of supervised cycling sprint interval training improved cardiorespiratory fitness and produced a favorable between-group LDL cholesterol signal, but most metabolic biomarkers and adipokines did not improve relative to a non-exercising control group.

## Population

- Adolescent boys diagnosed with childhood obesity, recruited from Tartu City and County, Estonia.
- Sample size: 28
- Age: 12-16 years; SIT 13.1 +/- 1.3 years and control 13.7 +/- 1.6 years at baseline.
- Sex: Boys only.
- Fitness level: No regular training other than school physical education twice weekly.
- Health status: Obesity without chronic disease or medication/therapy that would prohibit participation.

## Methodology

- Controlled 12-week exercise intervention with pre/post testing; group allocation was described as distribution into SIT and control groups but randomization was not clearly stated.
- 12 weeks
- Supervised laboratory/clinical exercise sessions in Estonia using Wattbike cycle ergometers.
- Controlled study design.

## Protocol

- 12-week cycling sprint interval training.
- Modality: Electronically braked cycle ergometer.
- Work intervals: 30 seconds all-out cycling.
- Recovery: 4 minutes active rest after each sprint.
- Sets or repetitions: 4 sprints in weeks 1-4, 5 sprints in weeks 5-8, 6 sprints in weeks 9-12.
- Intensity: All-out effort with target cadence at least 90 rpm; heart rate monitored with Polar H7.
- Session duration: 10-minute warm-up, sprint/rest block, and 5-minute cool-down.
- Frequency: 3 sessions per week on non-consecutive weekdays.
- Program length: 12 weeks.
- Progression: Sprint count increased from 4 to 5 to 6 across successive 4-week blocks.
- Non-exercising control.
- Modality: Habitual lifestyle.
- Program length: 12 weeks.
- Progression: No prescribed exercise progression.

## Outcomes

### VO2peak
Status: improved
SIT improved cardiorespiratory fitness compared with control, including relative VO2peak per body mass and lean body mass.

Between-group change: absolute VO2peak p = 0.044, VO2peak/kg p = 0.004, VO2peak/lean body mass p < 0.001.

### LDL cholesterol
Status: improved
LDL-c change was favorable for SIT compared with control.

Marginal change SIT -0.06 +/- 0.1 vs control +0.19 +/- 0.1 mmol/L; p = 0.025, eta2 = 0.19.

### Body fat
Status: mixed
No significant between-group body composition difference was reported, but body fat percentage decreased within the SIT group.

SIT body fat percentage 41.1 +/- 1.3 to 39.2 +/- 1.5; within-group p = 0.006.

### Glucose, insulin, HOMA-IR, leptin, adiponectin
Status: no clear change
Most measured cardiometabolic and adipokine markers did not show meaningful SIT-specific improvements.

No significant group differences for fasting glucose, insulin, HOMA-IR, leptin, or adiponectin.

## Practical Insights

- A low-volume cycling SIT program can improve fitness in adolescent boys with obesity when closely supervised.
- A 4-to-6 sprint progression over 12 weeks is a concrete dose model for youth cycling SIT.
- Metabolic biomarker changes were limited, so fitness gains should not be presented as broad cardiometabolic normalization.

## Limitations

- Small final analyzed sample.
- Randomization was unclear.
- Secondary analysis from a larger parent study and no a priori sample-size calculation for these outcomes.
- No caloric restriction or controlled diet.
- Boys only, limiting sex generalizability.
- Cycle ergometer all-out sprints may not translate directly to unsupervised bodyweight HIIT.

## Safety And Adherence

- Sessions were supervised and heart rate monitored.
- The article did not report specific adverse events.
- Attendance was at least 80%.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36231972/) (pubmed)
- [DOI](https://doi.org/10.3390/ijerph191912672) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9564781/) (full text)

## Agent Guidance

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