# Impact of a 12-week high-intensity interval training without caloric restriction on body composition and lipid profile in sedentary healthy overweight/obese youth

PMID: 29511662
Journal: Journal of Exercise Rehabilitation
Published: 2018-02-26
Authors: Khammassi M, Ouerghi N, Hadj-Taieb S, Feki M, Thivel D, Bouassida A

## Question

Does 12 weeks of running-based 30:30 HIIT without caloric restriction improve body composition, aerobic capacity, and lipid profile in sedentary overweight or obese young men?

## Summary

In sedentary overweight or obese young men, 12 weeks of progressive 30:30 running HIIT improved weight-related measures and between-group changes in aerobic capacity, total cholesterol, and triglycerides without a calorie-restriction program. The final analyzed sample was small and safety/adherence outcomes were not reported.

## Population

- Healthy untrained overweight or obese males aged 18-21 years with BMI >=25 kg/m2.
- Sample size: 16
- Age: 18-21 years; analyzed mean 19.4 +/- 1.1 years.
- Sex: Male only.
- Fitness level: Untrained/sedentary, although they had 3 hours per week of school physical education.
- Health status: Healthy overweight or obese; nonsmokers, nonalcohol drinkers, and no disease history expected to affect results.

## Methodology

- Randomized controlled pre/post intervention.
- 12 weeks of training within a 14-week testing-and-training period
- School/university exercise setting with running track testing in Tunisia.
- Randomized and controlled study design.

## Protocol

- Progressive 30:30 running HIIT.
- Modality: Running.
- Work intervals: 30 seconds.
- Recovery: 30 seconds active recovery.
- Sets or repetitions: Started at 15 repetitions and progressed to 27 repetitions.
- Intensity: Work at 100% maximal aerobic velocity; active recovery at 50% maximal aerobic velocity.
- Session duration: Warm-up plus 15-27 minutes of 30:30 intervals; cool-down was not clearly reported.
- Frequency: 3 sessions per week.
- Program length: 12 weeks.
- Progression: Number of repetitions and intensity increased over time; repetitions increased from 15 to 27.
- Control without intervention.
- Modality: Habitual activity.
- Program length: 12 weeks.
- Progression: No prescribed exercise intervention.

## Outcomes

### Body composition
Status: improved
Weight, BMI, waist circumference, and body fat percentage changes favored HIIT over control.

Delta weight -3.9 +/- 3.2; delta BMI -1.2 +/- 1.0, p<0.01; delta body fat -1.6 +/- 1.3, p<0.05; delta waist -5.0 +/- 3.6, p<0.01.

### Aerobic capacity
Status: improved
Within-group pre/post changes were not significant, but changes in maximal aerobic velocity and estimated VO2max were significantly better than control.

Delta MAV and delta VO2max differed between HIIT and control, p<0.01; HIIT delta MAV 1.5 +/- 1.0 and delta VO2max 4.8 +/- 3.8 vs control -0.3 +/- 0.5 and -1.1 +/- 1.9.

### Lipids
Status: mixed
Total cholesterol and triglyceride changes favored HIIT; LDL and HDL did not significantly change.

Delta total cholesterol 2.7 +/- 19.1 control vs -24.9 +/- 25.5 HIIT, p<0.05; delta triglycerides 3.9 +/- 40.5 control vs -38.6 +/- 27.2 HIIT, p<0.05.

## Practical Insights

- A 30:30 running format with MAV-based intensity is a concrete youth/young-adult HIIT template.
- The study supports weight and lipid improvements without prescribed caloric restriction, but diet and daily activity were not recorded.
- The protocol is more applicable to supervised track or school settings than unsupervised home workouts.

## Limitations

- Small analyzed sample.
- Male-only overweight/obese young adult sample.
- Food intake and daily physical activity outside sessions were not recorded.
- VO2max was estimated from a field test rather than directly measured.
- Safety, adherence, and dropout reasons were not reported.

## Safety And Adherence

- Participants were informed of potential risks and gave written consent.
- The article did not report adverse events, injuries, adherence, or dropout reasons.
- Four of 20 enrolled participants were not represented in the final analyzed results.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/29511662/) (pubmed)
- [DOI](https://doi.org/10.12965/jer.1835124.562) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5833956/) (full text)

## Agent Guidance

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