# Comparing Time Efficiency of Sprint vs. High-Intensity Interval Training in Reducing Abdominal Visceral Fat in Obese Young Women: A Randomized, Controlled Trial

PMID: 30123136
Journal: Frontiers in Physiology
Published: 2018-08-03
Authors: Tong TK, Zhang H, Shi H, Liu Y, Ai J, Nie J, Kong Z

## Question

Does a time-efficient sprint interval cycling program reduce abdominal visceral fat and other body fat depots as effectively as a longer HIIT cycling program in obese young women?

## Summary

In obese young women, 12 weeks of very short all-out cycling sprints and longer cycling HIIT both reduced body fat and abdominal visceral fat compared with no exercise. The sprint protocol required much less exercise time and produced a larger VO2max gain, but the longer HIIT protocol reduced abdominal subcutaneous fat and trunk fat more.

## Population

- Obese young female university students in China
- Sample size: 46
- Age: 18 to 23 years
- Sex: Female
- Fitness level: Low regular activity; PE classes only
- Health status: Obese by body fat percentage; otherwise screened healthy

## Methodology

- Three-arm randomized controlled trial
- 12 weeks
- Supervised university laboratory cycling intervention
- Randomized and controlled study design.

## Protocol

- SIT.
- Modality: Cycle ergometer.
- Work intervals: 6 s all-out sprint.
- Recovery: 9 s passive recovery.
- Sets or repetitions: 80.
- Intensity: All-out with progressive external load.
- Session duration: 8 min accumulated exercise plus 10-min warm-up and 5-min cool-down.
- Frequency: 3 to 4 sessions/week.
- Program length: 12 weeks.
- Progression: Load increased by 0.5 kp when 80 bouts were completed without undue fatigue.
- HIIT and control.
- Modality: Cycle ergometer; no exercise for control.
- Work intervals: 4 min at 90% VO2max.
- Recovery: 3 min passive recovery.
- Sets or repetitions: Repeated until 200 to 400 kJ target work completed.
- Intensity: 90% VO2max.
- Session duration: 27.6 to 48.2 min accumulated exercise plus warm-up/cool-down.
- Frequency: 3 to 4 sessions/week.
- Program length: 12 weeks.
- Progression: Target work increased from 200 to 400 kJ and workload adjusted after VO2max retesting.

## Outcomes

### Visceral fat
Status: improved
SIT reduced AVFA by 6.31 cm2 and HIIT by 9.70 cm2, with no significant difference between exercise protocols.

Both exercise groups improved versus control; SIT versus HIIT not significant for AVFA.

### Subcutaneous fat
Status: mixed
Both exercise groups reduced ASFA, but SIT reduced it less than HIIT.

SIT -17.4 cm2 versus HIIT -40.7 cm2; between-exercise difference p<0.05.

### VO2max
Status: improved
SIT increased VO2max more than HIIT.

SIT 30.7 to 38.5 mL/kg/min; HIIT 30.2 to 34.3 mL/kg/min; between-exercise p<0.01.

## Practical Insights

- Very short all-out intervals can change visceral fat with much lower exercise time.
- Longer HIIT may be preferable when subcutaneous abdominal fat reduction is a goal.
- All-out protocols need careful progression and screening.

## Limitations

- Small sample
- Young women only
- No objective confirmation of maximal effort in every sprint
- Cycling laboratory protocol limits app translation
- No long-term maintenance data

## Safety And Adherence

- No adverse events occurred during testing or training.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/30123136/) (pubmed)
- [DOI](https://doi.org/10.3389/fphys.2018.01048) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6085472/) (full text)

## Agent Guidance

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