# Effects of long or short duration stimulus during high-intensity interval training on physical performance, energy intake, and body composition

PMID: 29114503
Journal: Journal of exercise rehabilitation
Published: 2017 Aug
Authors: Alves ED, Salermo GP, Panissa VLG, Franchini E, Takito MY

## Question

Do long and short HIIT work intervals with the same work-to-rest ratio produce different effects on body composition, aerobic power, energy intake, hunger, and perceived exertion in untrained women?

## Summary

In 20 previously untrained young women, 6 weeks of cycling HIIT using either 15 longer one-minute intervals or 45 shorter 20-second intervals produced similar improvements in estimated VO2max and body composition. Neither protocol changed body mass, hunger perception, or energy intake, and perceived exertion declined across the training period.

## Population

- Previously untrained young women
- Sample size: 20
- Age: 25 +/- 6 years
- Sex: Female
- Fitness level: Previously untrained
- Health status: Apparently healthy; BMI 19.1-34.9

## Methodology

- Quasi-experimental two-group intervention study
- 6 weeks
- Controlled study design.

## Protocol

- Long-HIIT.
- Modality: Cycle ergometer.
- Work intervals: 1 min at 90% HRmax.
- Recovery: 30 s active recovery at 60% HRmax.
- Sets or repetitions: 15.
- Intensity: 90% predicted HRmax work; 60% HRmax recovery.
- Session duration: 15 min effort/recovery plus 3-min warm-up and 3-min cooldown.
- Frequency: 3 sessions/week.
- Program length: 6 weeks.
- Progression: Weekly load adjustment to reach target HR while maintaining about 60 rpm.
- Short-HIIT.
- Modality: Cycle ergometer.
- Work intervals: 20 s at 90% HRmax.
- Recovery: 10 s active recovery at 60% HRmax.
- Sets or repetitions: 45.
- Intensity: 90% predicted HRmax work; 60% HRmax recovery.
- Session duration: 15 min effort/recovery plus 3-min warm-up and 3-min cooldown.
- Frequency: 3 sessions/week.
- Program length: 6 weeks.
- Progression: Weekly load adjustment to reach target HR while maintaining about 60 rpm.

## Outcomes

### Fat mass
Status: improved
Fat mass and fat percentage decreased over time in both HIIT groups.

### VO2max
Status: improved
Estimated VO2max increased in both groups.

### Energy intake
Status: no clear change
Energy intake did not change and did not differ between groups.

### RPE
Status: improved
RPE decreased across training sessions with no group difference.

## Practical Insights

- When total high-intensity time and work:rest ratio are matched, short and long interval formats may be interchangeable for early adaptations.
- RPE can improve with repeated exposure even while workload rises.
- Short-term HIIT did not increase hunger or reported energy intake in this sample.

## Limitations

- Small sample
- Female-only young adult sample
- Quasi-experimental design and no non-exercise control group
- Estimated VO2max rather than direct gas exchange
- Adherence and adverse events not reported

## Safety And Adherence

- The article did not report adverse events, injuries, or dropouts.
- Heart rate and RPE were monitored during sessions.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/29114503/) (pubmed)
- [DOI](https://doi.org/10.12965/jer.1734962.481) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5667615/) (full text)

## Agent Guidance

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