Effects of high-intensity interval training combined with dietary intervention on body composition, cardiovascular function, endothelial cell function and blood lipid indexes in children with obesity: a randomized controlled trial.

All three intervention groups showed significant reductions in body mass index and fat mass after the 9-week intervention.

• 90 overweight children aged 9-12 years with BMI ≥ 23 kg/m² were randomly assigned to three groups (n=30 each) with a 1:1 gender ratio.
• Groups included MICT (60-80% of maximal aerobic speed), HIIT-only (100-120% of MAS), and Joint Intervention (HIIT plus dietitian-designed diet plan).
• All groups showed significant reductions in BMI and fat mass post-intervention.
• Pre- and post-intervention measurements covered body composition, cardiovascular function, endothelial function, and blood lipid profiles.
• Bonferroni post-hoc tests were used for pairwise comparisons.

The Joint Intervention group demonstrated superior improvements in body composition indicators compared to the other groups.

• Intergroup comparisons revealed that the Joint Intervention group had better outcomes in waist circumference, BMI, and fat mass compared to HIIT-only and MICT groups.
• Both HIIT groups showed greater reductions in body fat percentage compared to the MICT group (p < 0.05).
• The Joint Intervention group showed greater improvements in waist circumference and BMI compared to the HIIT-only group, with statistically significant differences (p < 0.05).

The Joint Intervention group exhibited better cardiovascular function outcomes compared to both the HIIT-only and MICT groups.

• Cardiac output (CO) and vasodilatory capacity index (VDC) values were significantly higher in the Joint Intervention group than in the HIIT-only and MICT groups.
• Heart rate (HR) and sympathetic nervous response (TCR) were lower in the Joint Intervention group compared to the HIIT-only group, with statistically significant differences (p < 0.05).
• These findings suggest that adding dietary intervention to HIIT produces additive cardiovascular benefits beyond exercise alone.

The Joint Intervention group showed superior endothelial cell function compared to the HIIT-only group post-intervention.

• Endothelin-1 (ET-1) and von Willebrand factor (vWF) levels were lower in the Joint Intervention group than in the HIIT-only group post-intervention.
• Flow-mediated dilation (FMD) and nitric oxide (NO) levels were higher in the Joint Intervention group compared to the HIIT-only group, with significant differences (p < 0.05).
• Endothelial function was assessed using biomarkers including endothelin-1 and nitric oxide.

The Joint Intervention group demonstrated greater improvements in blood lipid profiles compared to the HIIT-only group.

• Blood lipid profile improvements in the Joint Intervention group were statistically significantly greater than in the HIIT-only group (p < 0.05).
• Blood lipid profiles were measured both before and after the 9-week intervention period.
• Greater lipid improvements in the combined group suggest dietary intervention adds meaningful metabolic benefit beyond HIIT alone.