Different whole body HIIT protocols do not promote different muscle thickness and functional adaptations among healthy physically active subjects
Question
Do two different whole-body HIIT interval configurations produce different muscle-thickness and functional adaptations in healthy physically active adults?
Summary
In 34 healthy physically active young adults, two whole-body bodyweight HIIT formats performed twice weekly for 6 weeks both improved vastus lateralis muscle thickness, muscular endurance, and estimated VO2max. A 30-seconds work/10-seconds rest format was not meaningfully better or worse than a 40-seconds work/20-seconds rest format.
Methodology
- Healthy physically active Physical Education students and young adults
- 34 participants.
- Whole-body bodyweight exercises.
- Work intervals: 30 seconds.
- Recovery: 10 seconds passive recovery.
- Intensity: All-out effort.
- 2 sessions/week.
- 6 weeks.
- Randomized comparative exercise-training study
- Muscle thickness, Muscular endurance, and VO2max were tracked.
Outcomes
All outcomes
Both bodyweight HIIT configurations improved muscle thickness, muscular endurance, and VO2max.
Within-group improvements p<0.05.
Group difference
No significant differences were found between 30:10 and 40:20 protocols.
Between-group differences not significant.
Insights
- For active users, 30:10 and 40:20 whole-body HIIT can be treated as interchangeable options.
- Bodyweight HIIT is highly translatable, but all-out intensity should be scaled for beginners.
Limitations
- Small sample
- No inactive or no-exercise control group
- Active participants continued regular physical activity
- Adverse-event reporting absent despite reported 100% adherence
Safety
- Article did not report adverse events or injuries.
- All training protocols were supervised by researchers not involved in data analysis.
- Adherence was 100% in both groups; missed sessions were made up another day in the same week, and one G30x10 participant missed only the final Yo-Yo test.