Feasibility and efficacy of adding high-intensity interval training to a multidisciplinary lifestyle intervention in children with obesity-a randomized controlled trial
Question
Does adding a 12-week supervised HIIT program to a 12-month multidisciplinary lifestyle intervention improve BMI z-score, waist circumference, blood pressure, and health-related quality of life in children and adolescents with obesity, and is the program feasible?
Summary
This two-arm randomized controlled trial tested whether adding a 12-week community-based HIIT program to a 12-month multidisciplinary family lifestyle intervention improved outcomes in children and adolescents with obesity. HIIT did not add benefit for BMI z-score, waist circumference, or blood pressure versus lifestyle intervention alone, though the pooled cohort improved BMI z-score. HIIT improved child-reported quality of life at 3 months, was associated with lower dropout from the lifestyle intervention, and achieved 68% average attendance, but child-reported physical quality of life was lower in the HIIT group at 12 months after the exercise program ended.
Methodology
- Children and adolescents aged 9-16 years with obesity enrolled in Danish obesity treatment clinics.
- 173 participants.
- Playful group activities including strength-based exercise, ball games, and running games.
- Work intervals: 4 minutes.
- Recovery: 3 minutes active recovery.
- Intensity: Greater than 85% estimated HRmax target; actual average high-intensity time 8.7 +/- 4.8 minutes/session.
- 45-50 minutes prescribed; 47.5 +/- 10.5 minutes average.
- 3 sessions/week.
- 12 weeks HIIT plus 12 months TCOCT.
- Two-arm randomized controlled trial comparing 12 months of TCOCT lifestyle intervention with or without a supplementary 12-week HIIT program.
- BMI z-score, Waist circumference, Blood pressure, and Health-related quality of life were tracked.
Outcomes
BMI z-score
Adding HIIT did not further reduce BMI z-score compared with TCOCT alone, although BMI z-score improved across the pooled cohort.
Between-group MD 0.01 at 3 months, 95% CI -0.09 to 0.12, p=0.82; MD 0.06 at 12 months, 95% CI -0.07 to 0.19, p=0.34. Pooled cohort change -0.11 at 3 months and -0.20 at 12 months, both p<0.01.
Waist circumference
No significant between-group waist circumference benefit from HIIT.
MD 1.34 cm at 3 months, 95% CI -1.58 to 4.26, p=0.37; MD 2.81 cm at 12 months, 95% CI -0.51 to 6.12, p=0.09.
Blood pressure
No clinically relevant or significant between-group blood pressure effects were found.
Systolic BP MD 0.05 mmHg at 3 months, p=0.97; -0.33 mmHg at 12 months, p=0.83. Diastolic BP MD -0.72 mmHg at 3 months, p=0.47; -0.51 mmHg at 12 months, p=0.66.
Health-related quality of life at 3 months
HIIT improved child-reported PedsQL total and psychosocial scores more than control at 3 months.
PedsQL child total MD 2.73, 95% CI 0.01 to 5.44, p=0.05; psychosocial MD 3.85, 95% CI 0.96 to 6.74, p=0.01.
Health-related quality of life at 12 months
At 12 months, child-reported physical score and parent-proxy physical score were lower in HIIT than control.
PedsQL child physical MD -6.89, 95% CI -10.97 to -2.83, p<0.01; parent physical MD -5.04, 95% CI -9.53 to -0.56, p=0.03.
Feasibility and adherence
HIIT attendance averaged 68%, 61.1% completed at least 70% of sessions, and dropout was lower than control at both 3 and 12 months.
Attendance 68.0 +/- 23.2%; dropout HIIT vs control 7.8% vs 20.5% at 3 months and 25.5% vs 48.2% at 12 months.
Insights
- For children with obesity, HIIT may be more useful as an engagement and quality-of-life support than as an add-on weight-loss lever.
- Playful, non-competitive, varied movement formats are important pediatric HIIT design features.
- A short supervised HIIT program needs a continuation plan; participants may struggle after the structured program ends.
- App translation should keep pediatric HIIT claims bounded to supervised, family-supported contexts.
Limitations
- Sample size was below the planned 202 participants.
- COVID-19 disrupted recruitment and intervention timing and may have decreased the intervention signal.
- Some teams had delayed HIIT sessions and outdoor sessions because of restrictions.
- The flexible activity approach may have reduced the intensity achieved during sessions.
- No adverse-event details were reported in the main text.
- No structured exercise comparator was included.
Safety
- No adverse-event results were reported in the main text.
- Children with physical limitations or mental illness that would complicate participation were excluded.
- The HIIT intervention used trained in-person supervisors and continuous HR monitoring.