PMID 39183975

Research
All papers

Effect of eight-week high-intensity interval training versus moderate-intensity continuous training programme on body composition, cardiometabolic risk factors in sedentary adolescents

Sun F, Williams CA, Sun Q, Hu F, Zhang T

Question

Do 8 weeks of running-based HIIT and MICT improve body composition and cardiometabolic risk factors in sedentary adolescents, and are there differences between the two programs?

Summary

This small randomized trial tested 8 weeks of field-based running HIIT against moderate continuous running and usual activity in sedentary normal-weight Chinese university-age adolescents. HIIT and MICT similarly reduced several body-fat measures, but HIIT had additional within-group improvements in waist/hip ratio, blood pressure, and triglycerides. Insulin resistance and several lipids did not significantly improve.

Methodology

  • Sedentary normal-weight Chinese adolescents/university entrants with no known disease or exercise contraindications.
  • 18 participants.
  • Outdoor running sprints.
  • Work intervals: 8 seconds all-out in weeks 1-4; 10 seconds all-out in weeks 5-8.
  • Recovery: 24 seconds active walking recovery in weeks 1-4; 30 seconds in weeks 5-8.
  • Intensity: 85-95% HRmax; actual recorded exercise HR generally corresponded to target intensity.
  • 30 minutes including 5-minute warm-up, 20-minute sprint interval training, and 5-minute cooldown/stretching.
  • 3 sessions/week.
  • 8 weeks.
  • Three-arm randomized controlled trial with HIIT, MICT, and no-intervention control groups.
  • Body composition, Blood pressure, Fasting cardiometabolic biomarkers, and Lipids were tracked.

Outcomes

Body fat

HIIT and MICT both reduced body fat mass, body fat percentage, and visceral fat area; HIIT uniquely reduced waist/hip ratio.

BF: HIIT p=0.021 ES=0.19, MICT p=0.016 ES=0.30; BFP: HIIT p=0.037 ES=0.17, MICT p=0.041 ES=0.28; VFA: HIIT p=0.001 ES=0.35, MICT p=0.003 ES=0.49; WHR improved in HIIT p=0.033 ES=0.43 but not MICT.

Improved

Blood pressure and triglycerides

Within-group pairwise comparisons showed systolic BP, diastolic BP, and triglycerides decreased in HIIT but not MICT or control.

SBP p=0.018 ES=0.84; DBP p=0.008 ES=1.76; TG p=0.004 ES=1.33.

Improved

Insulin resistance and inflammation

The study did not confirm significant improvements in insulin resistance or hs-CRP, although HOMA-IR slightly decreased in HIIT and increased in MICT/control.

Authors state statistical results did not confirm an effective insulin resistance change; HIIT HOMA-IR decreased 5.63% while MICT and control increased.

No clear change

BMI and cholesterol fractions

BMI, total cholesterol, HDL-C, and LDL-C did not significantly change.

Reported as p > 0.05.

No clear change

Insights

  • Very short running sprints with long active recovery can improve some body-composition markers in sedentary normal-weight adolescents.
  • For cardiometabolic markers, the strongest signals were blood pressure and triglycerides in the HIIT group, not broad lipid or insulin improvements.
  • Heart-rate monitoring and professional supervision were part of the field protocol.

Limitations

  • Very small completed sample with only six participants per group.
  • Pandemic conditions limited enrollment and protocol fidelity.
  • Normal-weight late adolescents limit generalization to adults, children, or adolescents with obesity.
  • No long-term follow-up and no detailed adverse-event table.
  • Diet was recommended but not tightly controlled.

Safety

  • No testing- or training-related severe injuries occurred.
  • One participant was excluded before randomization for bradycardia after ECG screening.