Effectiveness of high intensity and sprint interval training on metabolic biomarkers, body composition, and physical fitness in adolescents: randomized controlled trial
Question
What are the effects of school-based HIIT and SIT on adolescent body composition, blood pressure, lipids, glucose, cardiorespiratory fitness, and strength, and do the two protocols differ?
Summary
In a Spanish secondary-school randomized trial, adolescents completed either SIT, HIIT, or regular physical education for 8 weeks. Both interval programs improved body composition and strength markers, but the 3 x 2 min HIIT protocol produced broader benefits than the 6 x 1 min SIT protocol, including improvements in blood pressure, heart rate, and estimated VO2max. The study was school-relevant but had attrition and a final analyzed sample smaller than randomized.
Methodology
- Healthy adolescents recruited from a high school in Murcia, Spain.
- 60 participants.
- Running.
- Work intervals: 3 x 2 min.
- Recovery: 2 min rest at 50-55%.
- Intensity: 80-85% during work.
- 12 min intervention block.
- 2 sessions/week.
- 8 weeks.
- Randomized controlled trial with SIT, HIIT, and regular physical education control groups.
- Body composition, Blood pressure and heart rate, Lipids and glucose, and VO2max were tracked.
Outcomes
Body composition and strength
Both HIIT and SIT reduced fat mass and trunk fat mass and increased lean mass, handgrip, and long jump after sex adjustment.
Fat and trunk fat p<0.01; lean mass p=0.01/<0.01; handgrip p<0.01; long jump p=0.05-0.04.
Cardiovascular fitness and BP
HIIT, but not SIT, significantly improved blood pressure, diastolic blood pressure, heart rate, and VO2max.
HIIT p<0.05 for BP/DBP/HR/VO2max.
LDL
HIIT showed only a tendency toward LDL reduction.
p value described as tendency, not significant.
Protocol comparison
The 3 x 2-min HIIT protocol produced more benefits than the shorter, more intense SIT protocol.
Insights
- A 12-min 3 x 2-min running HIIT block is a plausible school-friendly structure.
- For adolescents, slightly longer intervals at lower intensity may be more beneficial than harder 1-min SIT.
- Report and monitor attrition when using school HIIT evidence.
Limitations
- Small sample
- Single secondary school
- Final analyzed sample smaller than randomized
- No long-term follow-up
- Adverse events not clearly reported
Safety
- Adverse events were not specifically reported.
- Exercise-limiting pathology was excluded.