The effect of 4 weeks of high-intensity interval training and 2 weeks of detraining on cardiovascular disease risk factors in male adolescents
Question
What effect do 4 weeks of HIIT running and 2 weeks of detraining have on vascular function and traditional cardiovascular risk factors in adolescent boys?
Summary
In healthy adolescent boys, 4 weeks of school-based running HIIT improved brachial artery flow-mediated dilation, a macrovascular function marker, but did not change microvascular function, body composition, glucose, insulin, or lipids. The vascular improvement was no longer present after 2 weeks without training. Attendance was excellent and no adverse events occurred, but the sample was small and male-only.
Methodology
- Healthy male adolescents.
- 19 participants.
- Shuttle running.
- Work intervals: 1 min.
- Recovery: 75 s passive rest.
- Intensity: 90% maximal aerobic speed.
- About 18-26 min plus 1 min warm-up depending on week.
- 3 sessions/week.
- 4 weeks.
- Randomized controlled training and detraining study.
- Macrovascular function, Microvascular function, Body composition, and Glucose, insulin, and lipids were tracked.
Outcomes
Flow-mediated dilation
FMD was significantly greater in TRAIN than CON after 4 weeks, but no longer significantly different after 2 weeks detraining.
Post F(15)=5.33, p=0.036, ES=0.49; detraining p=0.062.
Microvascular function
No training effect was detected for peak reactive hyperemia.
p=0.821.
Body composition and blood biomarkers
No between-group differences were observed after training for BMI, fat mass, fat-free mass, body fat percentage, glucose, insulin, cholesterol fractions, or TAG.
Body composition p>=0.14; biomarkers p>=0.18.
Adherence and safety
All TRAIN participants completed 100% of sessions without adverse events.
Insights
- Short adolescent HIIT may need continued programming to preserve vascular benefits.
- A simple running protocol can be delivered before school lessons with strong adherence under supervision.
- Do not promise broad metabolic or body composition changes from only 4 weeks in healthy boys.
Limitations
- Small sample
- Male adolescents only
- Short intervention
- Surrogate vascular outcome
- Some missing vascular/lipid data
Safety
- All TRAIN participants completed all sessions without adverse events.
- Two participants failed to complete the overall study due to illness or time constraints.