# Comparison of High-Intensity Interval Training and Moderate-to-Vigorous Continuous Training for Cardiometabolic Health and Exercise Enjoyment in Obese Young Women: A Randomized Controlled Trial

PMID: 27368057
Journal: PLOS ONE
Published: 2016-07-01
Authors: Kong Z, Fan X, Sun S, Song L, Shi Q, Nie J

## Question

How do 5 weeks of low-volume cycling HIIT and moderate-to-vigorous continuous cycling compare for cardiometabolic outcomes, sex hormones, and exercise enjoyment in obese young women?

## Summary

In sedentary obese young women, 5 weeks of low-volume cycling HIIT improved VO2peak about as much as much longer moderate-to-vigorous continuous cycling and was more enjoyable. Continuous training produced clearer within-group reductions in body mass and fat measures, while HIIT mostly maintained body weight. Neither training mode improved blood lipids, and the trial lacked a no-exercise control.

## Population

- Sedentary obese young women.
- Sample size: 31
- Age: 18-35 years by inclusion criteria.
- Sex: Female.
- Fitness level: Sedentary, less than 60 min exercise/week.
- Health status: Obese by body fat percentage >30%, cleared for vigorous exercise.

## Methodology

- Two-arm randomized controlled training trial without no-exercise control.
- 5 weeks.
- Supervised exercise testing and cycle training.
- Randomized and controlled study design.

## Protocol

- Cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 8 s sprinting.
- Recovery: 12 s passive rest.
- Sets or repetitions: Up to 60 repetitions.
- Intensity: Sprint as hard as possible; initial resistance 1.0 kg with progression.
- Session duration: About 26 min including warm-up/cool-down.
- Frequency: 4 sessions/week.
- Program length: 5 weeks.
- Progression: Increase resistance by 0.5 kg after two consecutive completed sessions at current load.
- MVCT.
- Modality: Continuous cycle ergometer.
- Work intervals: 40 min continuous cycling.
- Intensity: 60% VO2peak progressing to 80% VO2peak.
- Session duration: About 46 min including warm-up/cool-down.
- Frequency: 4 sessions/week.
- Program length: 5 weeks.
- Progression: Resistance increased by 0.5 kg after two successful sessions until 80% VO2peak.

## Outcomes

### VO2peak
Status: improved
Both HIIT and MVCT increased VO2peak by about 10%.

HIIT +9.1%, MVCT +10.3%, p = .010, partial eta2 = .41.

### Body composition
Status: mixed
MVCT reduced body water, fat mass, and percent body fat within group; no clear adjusted between-group advantage.

MVCT TBW -1.8% p = .034; FM -4.7% p = .002; PBF -2.9% p = .016.

### Blood lipids
Status: no clear change
Neither group had favorable lipid changes.

### Enjoyment
Status: improved
HIIT was more enjoyable than MVCT.

First two sessions PAES 65 +/- 10 HIIT vs 45 +/- 17 MVCT, p = .001.

## Practical Insights

- Micro-interval cycling can improve fitness with less time and higher enjoyment than continuous cycling.
- Weight/fat-loss claims should be modest for a 5-week HIIT dose.
- Enjoyment can be measured repeatedly as a product signal.

## Limitations

- Small sample.
- No no-exercise control.
- Short 5-week intervention.
- Menstrual phase and possible PCOS not fully controlled.
- BIA body composition.
- Cycling protocol not directly bodyweight-translatable.
- No detailed adverse-event reporting.

## Safety And Adherence

- No adverse-event details were reported.
- Participants required medical clearance for vigorous exercise.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/27368057/) (pubmed)
- [DOI](https://doi.org/10.1371/journal.pone.0158589) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4930190/) (full text)

## Agent Guidance

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