# Cardiorespiratory and Hematological Responses to High-Intensity Interval Training in Adolescent Girls With Overweight or Obesity: A Randomized Controlled Trial

PMID: 42050353
Journal: European journal of sport science
Published: 2026 May
Authors: Abassi W, Ouerghi N, Feki M, Marsigliante S, Bouassida A, Knechtle B, Muscella A

## Question

Does 10 weeks of supervised HIIT improve body composition, cardiorespiratory fitness, hematological markers, plasma volume, and muscle/metabolic strain markers in adolescent girls with overweight or obesity compared with control?

## Summary

In adolescent girls with overweight or obesity, a supervised 10-week running-based HIIT program improved body mass, BMI, body fat, waist circumference, maximal aerobic speed, and estimated VO2max compared with a usual-activity control pattern. Hematological changes suggested plasma volume expansion, and creatine kinase and lactate dehydrogenase decreased within the HIIT group. The trial was small and VO2max was estimated from a field test rather than directly measured.

## Population

- Adolescent girls with overweight or obesity.
- Sample size: 28
- Age: Completers mean 16.2 +/- 0.92 years.
- Sex: Female.
- Fitness level: School PE participants, no recent structured physical activity allowed.
- Health status: BMI >=95th percentile for age; no major medical conditions.

## Methodology

- Parallel randomized controlled trial.
- 10 weeks, 30 HIIT sessions planned.
- Public high schools in Kalaat Sinan, Kef Governorate, Tunisia; supervised by qualified physical education instructors.
- Randomized and controlled study design.

## Protocol

- 10-week running HIIT.
- Modality: Running.
- Work intervals: 15 s at 90-105% MAS.
- Recovery: 15 s active recovery at 50% MAS.
- Sets or repetitions: 4 sets x 6 reps in weeks 1-2; 4 sets x 8 reps in weeks 3-10.
- Intensity: 90% MAS weeks 1-4, 95% weeks 5-6, 100% weeks 7-8, 105% weeks 9-10.
- Session duration: 10 min warm-up, interval sets, 5 min cool-down.
- Frequency: 3 sessions/week.
- Program length: 10 weeks.
- Progression: Repetitions and %MAS progressed over time.
- Control.
- Modality: Usual activities and standard physical education.
- Program length: 10 weeks.

## Outcomes

### Body composition
Status: improved
HIIT produced within-group reductions in body mass, BMI, body fat percentage, and waist circumference; control did not change.

Body mass p<0.001; BMI p<0.001; body fat p=0.001; waist circumference p<0.001.

### Estimated aerobic fitness
Status: improved
HIIT increased maximal aerobic speed and estimated VO2max.

MAS p=0.007; estimated VO2max p=0.007.

### Hematological profile
Status: mixed
HIIT reduced erythrocytes, hemoglobin, and hematocrit and increased plasma volume variation; authors interpret as plasma volume expansion but hemoglobin was lower than control post-intervention.

Erythrocytes p=0.007; hemoglobin p=0.019 and lower than control p=0.004; hematocrit p=0.004; PVV higher than control p<0.001.

### CK and LDH
Status: improved
Creatine kinase and lactate dehydrogenase decreased in the HIIT group.

CK p=0.049; LDH p=0.032.

## Practical Insights

- Short 15-s running intervals with equal active recovery are a realistic school-based HIIT structure.
- Progressing speed from 90% to 105% MAS over 10 weeks can produce estimated fitness and body composition improvements in supervised adolescent girls.
- VO2max findings should be described as estimated from a field test.

## Limitations

- Small sample size.
- Single-sex adolescent sample.
- No long-term follow-up.
- VO2max estimated rather than directly measured.
- Limited reporting of achieved interval intensity.

## Safety And Adherence

- Participants could discontinue or modify training for musculoskeletal pain, cardiovascular overload signs, personal request, or medical advice.
- No specific adverse events were reported in the article text reviewed.
- Sessions were supervised by qualified physical education instructors.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/42050353/) (pubmed)
- [DOI](https://doi.org/10.1002/ejsc.70181) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13124659/) (full text)

## Agent Guidance

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