Vitamin D supplementation attenuates exercise induced muscle damage: A meta-analysis of randomized control trials

Abstract

Purpose: This meta-analysis evaluated the effectiveness of vitamin D (Vit D) supplementation in reducing muscle damage, inflammation, and perceived muscle soreness. Methods: A structured literature search was performed Web of Science, Scopus, and Google Scholar databases to identify relevant randomized controlled trials. Six studies comprising 209 participants (155 males, 54 females) met the inclusion criteria. Outcome measures included creatine kinase (CK), lactate dehydrogenase (LDH), serum cytokines, and visual analog scale (VAS) for muscle soreness. Post-exercise muscle damage was assessed by comparing the Vit D supplementation and placebo groups using participant numbers, mean differences, and standard deviations. Cohen’s d was used to compute the standardized mean differences (SMDs) for each study group. These values were then weighted based on the inverse of their variance to give more importance to studies with more precise results. A random effects model was selected to estimate the total effect size along with a 95% CI. Results: The analysis revealed a moderate effect of Vit D supplementation on muscle damage markers (CK = -0.46, 95% CI: -0.94, 0.02, LDH: - 0.28, 95% CI: -0.87, -0.30) and inflammatory markers (Serum Cytokines: -0.50, 95% CI: -0.90, -0.11). Strongest impact was observed on perceived muscle soreness (Visual Analogue Scale: -1.34, 95% CI: -1.91, -0.77). Notable improvements were highlighted in Vit D dosage and intervention duration but lacked consistency among the outcomes which contributing further variation in findings. Conclusion: Vit D demonstrated a moderate effect on muscle damage and inflammatory processes, its strongest impact was observed on perceived muscle soreness. However, inconsistencies in dosage, intervention duration, and study protocols limit the ability to draw robust conclusions. Future research should emphasis on standardized protocols, larger sample sizes, and consideration of factors such as skin biosynthesis of Vit D, climatic conditions, and controlled muscle damage models to enhance the reliability of findings.