Synergistic Effects of Vitamin D Supplementation and Resistance Training on IGF-1 and Muscle Health: A Systematic Review

Abstract Background The interaction between vitamin D and IGF-1 in resistance-power training is not fully elucidated, despite their established roles in muscle physiology. Research compiles data about how resistance training and vitamin D supplementation affect the results of muscle parameters alongside serum IGF-1 concentrations. Methods The research analysis utilized PRISMA guidelines. Seventeen studies were reviewed, including eleven randomized controlled trials (RCTs) and six observational studies. The included studies examined children, adults, the elderly, and patients with metabolic or hormonal disorders. The primary outcomes were serum IGF-1 and IGF-binding proteins (IGFBPs), as well as muscle strength and physical function. Results 17 studies were included in the systematic review. Voluntary muscle expression of IGF-1 increased by at least 20% to 30% in elderly women through resistance training (p < 0.01) though combined training increased muscle IGF-1 levels and functional capacity by 22% (p = 0.01). Data confirm a positive association between serum 25(OH)D and IGF-1 levels, while limited evidence suggests a moderate reduction in IGFBPs. Conclusion The combination and individual effects of vitamin D supplementation with resistance training systems enhance IGF-1 bioavailability and muscle health in vitamin D-deficient adults.