# The Impact of Different High-Intensity Interval Training Protocols on Body Composition and Physical Fitness in Healthy Young Adult Females

PMID: 30622842
Journal: BioResearch Open Access
Published: 2018-12-28
Authors: Brown EC, Hew-Butler T, Marks CRC, Butcher SJ, Choi MD

## Question

Do multimodal and rowing HIIT differ in their effects on body composition, cardiovascular fitness, and muscular fitness in healthy young adult women?

## Summary

In a small randomized 12-week trial of healthy nonobese young women, both multimodal HIIT and rowing HIIT improved VO2max, lean mass, bone mineral content, and several strength/power outcomes. Multimodal HIIT improved deadlift 1RM more than rowing HIIT, but most outcomes did not differ between groups.

## Population

- Healthy nonobese recreationally active young adult women.
- Sample size: 16
- Age: 23 +/- 5.08 years
- Sex: Women
- Fitness level: Recreationally active, not systematically trained
- Health status: Apparently healthy

## Methodology

- Parallel-group randomized trial
- 12 weeks
- University recreation and health-sciences facilities
- Randomized and controlled study design.

## Protocol

- Multimodal HIIT.
- Modality: Barbell, dumbbell/bodyweight, and sprint-like movements.
- Work intervals: 60 s.
- Recovery: 3 min rest.
- Sets or repetitions: 6 sets per session.
- Intensity: As much effort as possible; HR >=90% estimated HRmax.
- Session duration: About 60 min session window.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Increase weight/speed after reaching prescribed repetitions; eight workouts repeated.
- Rowing HIIT.
- Modality: Rowing ergometer.
- Work intervals: 60 s.
- Recovery: 3 min rest.
- Sets or repetitions: 6 sets per session.
- Intensity: As much effort as possible; HR >=90% estimated HRmax.
- Session duration: About 60 min session window.
- Frequency: 3 sessions/week.
- Program length: 12 weeks.
- Progression: Participants encouraged to increase meters rowed each session.

## Outcomes

### VO2max
Status: improved
VO2max improved for the whole sample with no significant group interaction.

F(1,12)=8.52, p=0.01, partial eta squared=0.415.

### Lean mass/BMC
Status: improved
Lean mass and bone mineral content increased in the whole sample with no significant group interaction.

Lean mass p<0.001; BMC p<0.001.

### Deadlift strength
Status: improved
Deadlift 1RM increased more in multimodal HIIT than rowing HIIT.

Time by group F(1,12)=4.85, p=0.048.

### Adiposity
Status: mixed
Total body-fat percentage decreased, but fat mass, waist, waist-to-height ratio, and VAT did not significantly change.

Total body fat percentage p=0.04; no significant interactions.

## Practical Insights

- Supervised multimodal HIIT can improve strength and aerobic markers but loaded movements require skill preparation.
- Rowing HIIT plus identical warm-up also improved several muscular fitness outcomes, so strength changes should not be attributed only to resistance circuits.

## Limitations

- Small sample
- No non-exercise control group
- Healthy nonobese young women only
- Some missing outcome data
- Predicted HRmax used for session intensity
- No broad-jump familiarization

## Safety And Adherence

- No adverse events were reported during testing.
- Two muscle strains occurred outside exercise sessions during the intervention period, one in each group, causing one missed session each.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/30622842/) (pubmed)
- [DOI](https://doi.org/10.1089/biores.2018.0032) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6323591/) (full text)

## Agent Guidance

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