# Effects of 12-week combined training versus high intensity interval training on cardiorespiratory fitness, body composition and fat metabolism in obese male adults

PMID: 36820014
Journal: Journal of exercise science and fitness
Published: 2023 Apr
Authors: D'Alleva M, Vaccari F, Graniero F, Giovanelli N, Floreani M, Fiori F, Marinoni M, Parpinel M, Lazzer S

## Question

Does a combined high-intensity interval plus moderate continuous training protocol produce similar fitness, body composition, and fat-metabolism effects as energy-matched HIIT in obese male adults?

## Summary

In inactive obese adult men, 12 weeks of home-based run/walk HIIT improved body mass, fat mass, cardiorespiratory fitness, and fat-oxidation outcomes. A combined protocol with fewer HIIT intervals plus moderate continuous exercise produced similar benefits with lower heart rate and perceived exertion but longer session duration.

## Population

- Healthy inactive obese male adults aged 18-50 years, BMI at least 30, without major cardiovascular, respiratory, neurologic, musculoskeletal, metabolic, or endocrine disease. Final groups were combined training n=18 and HIIT n=16.
- Sample size: 34
- Age: 18-50 years; mean about 39 years
- Sex: Male
- Fitness level: Physically inactive
- Health status: Healthy obese adults without major comorbidities

## Methodology

- Randomized 12-week comparative exercise intervention without inactive control
- 12 weeks
- Home-based outdoor training with remote HR monitoring
- Randomized and controlled study design.

## Protocol

- Run/walk HIIT.
- Modality: Outdoor running/walking on flat terrain.
- Work intervals: 5-7 x 2 min high-intensity bouts.
- Recovery: 1 min walking recovery.
- Sets or repetitions: 5 to 7 intervals.
- Intensity: Work at speed corresponding to 95% VO2peak; recovery at 50% VO2peak.
- Session duration: Energy-matched to about 20 kJ/kg fat-free mass plus warm-up/cool-down.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Interval number adjusted from 5 to 7 to maintain matched energy expenditure.
- Combined HIIT plus moderate continuous training.
- Modality: Outdoor running/walking.
- Work intervals: 3 x 2 min at 95% VO2peak.
- Recovery: 1 min walking at 50% VO2peak between intervals, followed by continuous exercise.
- Sets or repetitions: 3 intervals plus 30 min continuous exercise.
- Intensity: Intervals at 95% VO2peak and continuous phase at 60% VO2peak.
- Session duration: Longer than HIIT, energy-matched to about 20 kJ/kg fat-free mass.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Not described beyond speed adjustment from HR response.

## Outcomes

### Body composition
Status: improved
Both groups reduced body mass, BMI, waist, and fat mass with no significant group-by-time difference.

### VO2peak
Status: improved
Absolute and fat-free-mass-normalized VO2peak increased in both groups by about 16% with no between-group difference.

### Fat oxidation
Status: improved
Fat oxidation measures improved in both groups without a clear superiority of one protocol.

### Training tolerance
Status: mixed
Combined training produced lower mean HR and RPE but required longer duration and more distance than HIIT.

## Practical Insights

- Energy-matched HIIT and combined training can both improve fitness and fat-loss markers in screened obese men.
- A combined protocol may be more tolerable because it lowers perceived exertion and heart rate, though it takes longer.
- Remote HR monitoring can support home-based exercise delivery when in-person sessions are limited.

## Limitations

- No inactive control group.
- Participants were healthy obese men without comorbidities, limiting clinical generalization.
- Only one combined-training ratio was tested.
- Remote real-life training introduced less control than laboratory delivery.
- Dietary influences cannot be ruled out.

## Safety And Adherence

- No adverse events occurred during the 12-week intervention. One person assigned to HIIT left before starting because heart disease was identified.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36820014/) (pubmed)
- [DOI](https://doi.org/10.1016/j.jesf.2023.01.004) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9937988/) (full text)

## Agent Guidance

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