Combined Effects of Aerobic Training and Vitamin D Supplementation on Inflammatory Markers and Metabolic Health in Overweight Middle-School Girls: A Randomized Controlled Trial

Introduction: Overweight during early adolescence is associated with chronic low-grade inflammation and increased cardiometabolic risk. School-based aerobic exercise is a practical strategy to improve metabolic health, and vitamin D may provide additional anti-inflammatory benefits.
Objective: To examine the effects of aerobic training (AT) with or without vitamin D supplementation on inflammatory markers and metabolic outcomes in overweight middle-school girls.
Methods: In this 12-week, three-arm randomized controlled trial, overweight girls (11–14 years) were randomly assigned to AT plus vitamin D (AT+VitD), AT only (AT), or control (CON). The AT was conducted 3 sessions/week at moderate-to-vigorous intensity. The AT+VitD group received vitamin D (2000 IU/day). Fasting blood samples were collected at baseline and post-intervention to assess hs-CRP, IL-6, TNF-α, fasting glucose, insulin, HOMA-IR, HbA1c, and lipid profile. Anthropometrics, waist indices, and blood pressure were also measured. Data was analyzed using ANCOVA adjusted for baseline values.
Results: After 12 weeks, hs-CRP, IL-6, and TNF-α showed significant group effects (p < 0.05), with the greatest reductions in AT+VitD, followed by AT, versus CON. Fasting insulin and HOMA-IR also improved significantly in both intervention groups, with larger changes in AT+VitD. Waist indices, systolic blood pressure, and lipid profile improved favorably, generally with the strongest effects in the combined group. Serum 25(OH)D increased significantly only in AT+VitD (p < 0.05), confirming supplementation effectiveness.
Conclusion: Combining AT with vitamin D may be an effective, feasible strategy to reduce inflammation-related cardiometabolic risk during early adolescence.