EXPRESS: Effects of Aerobic, Resistance, and Combined Exercise on Inflammatory Markers in Patients with Metabolic Syndrome: A Systematic Review and Network Meta-Analysis

BACKGROUND: The comparative effectiveness of different exercise modalities on systemic inflammation in patients with metabolic syndrome (MetS) remains poorly defined. OBJECTIVE: To systematically evaluate and rank the effects of aerobic exercise (AE), resistance training (RT), and combined training (COM) on inflammatory markers (CRP, TNF-α, and IL-6) in MetS. METHODS: A network meta-analysis of 28 randomized controlled trials (RCTs) was conducted. Data were synthesized using frequentist random-effects models. Treatment efficacy was ranked using the Surface Under the Cumulative Ranking Curve (SUCRA). RESULTS: Compared to the control group, all exercise modalities were associated with reductions in TNF-α levels, though the strength of this evidence is limited by high heterogeneity and potential publication bias. Among the interventions, COM showing the greatest effect (SMD = -1.74; 95% CI: -3.06 to -0.43; SUCRA = 75.7%), followed by RT and AE. For CRP, significant reductions were observed in COM (SMD = -0.79; 95% CI: -1.36 to -0.21; SUCRA = 86.8%) and AE (SMD = -0.64; 95% CI: -0.95 to -0.32), while RT demonstrated a smaller effect. No modalities reached statistical significance for IL-6, although RT ranked highest in SUCRA (75.8%). Notably, CRP findings were robust with moderate certainty and no publication bias (p = 0.86), whereas TNF-α and IL-6 exhibited significant publication bias (p < 0.05) and extreme heterogeneity (I2 > 90%). CONCLUSION: Exercise, particularly COM, appears to be a promising intervention for reducing CRP and TNF-α in MetS. While the findings for CRP are robust, results for TNF-α should be interpreted with caution due to observed heterogeneity and potential publication bias.