Effects of Nutritional Supplements on Explosive Lower Limb Performance in Volleyball Players: A Systematic Review and Network Meta-Analysis.

Background: Explosive lower limb power, a critical determinant of success in volleyball, is a prime candidate for focused research. Consequently, nutritional supplements are commonly employed to gain an ergogenic edge. Despite this widespread practice, a comprehensive and evidence-based ranking of supplements for improving this key attribute is lacking, leaving athletes and practitioners without targeted evidence to guide decisions. Methods: PubMed, Web of Science, CENTRAL, and Embase were searched from inception to 1 August 2025. We included RCTs in volleyball athletes (≥14 years) with ≥1-week interventions and relevant explosive lower limb performance outcomes. A Bayesian NMA estimated effects with 95% credible intervals (CrIs) and SUCRA; certainty was appraised with CINeMA. Results: A total of 35 RCTs (n = 838 volleyball athletes) examining 13 different supplements were included. The results indicated that β-alanine was associated with the greatest improvement in vertical jump (MD 4.6; 95% CrI 1.2-7.8), followed by creatine (MD 3.7; 0.57-6.9) and caffeine (MD 2.1; 0.06-4.1). It also appeared to be the most promising method for substantially increasing lower limb peak power (SMD 1.1; 0.21-2.0). No statistically significant improvement was found in lower limb mean power, and no serious adverse events were reported. Conclusions: Among volleyball athletes, β-alanine appeared most promising effective supplement for enhancing key components of explosive lower limb performance, specifically vertical jump height and peak power. Creatine and caffeine are also effective for improving vertical jump height. However, these findings are based on low-to-moderate certainty of evidence; they should be interpreted with caution and regarded as preliminary. Supplement strategies should be individualized by age and competitive level; further, high-quality, standardized randomized controlled trials are warranted to validate these initial observations.