Effects of Acute Caffeine Ingestion on Physical Performance and Skill Execution in Volleyball Players: A Systematic...

It is well established that oral caffeine administration (3-9 mg/kg) is ergogenic, enhancing numerous aspects of physical performance including strength and power. However, the extent to which these effects translate to volleyball-specific skills remains unclear. The purpose of this study was to systematically review the effects of acute caffeine ingestion on performance outcomes in volleyball-specific actions. A systematic review of published studies was conducted using scientific databases from their inception through December 2024 (registered in PROSPERO, CRD420251006314). We included studies with blinded crossover experimental designs that compared caffeine ingestion to a placebo in samples of volleyball players performing physical performance tests or volleyball-specific tasks. The data from these studies were meta-analyzed to calculate standardized mean differences (Hedges' g) between placebo and caffeine conditions, using a random-effects model. The Q and I² statistic was calculated to verify the degree of similarity in the observed mean differences and the degree of heterogeneity, respectively. In total, after examining 60 effect sizes include 9 RCTs, 123 volleyball players with caffeine doses 1.7-6.4 mg/kg and administered 15-60 min pre-exercise, the meta-analysis indicated that caffeine improved performance in jumping activities (g = 0.24, p =0.009), strength-based tasks (g = 0.31, p =0.006) and performance in volleyball-specific skill tasks (g = 0.52, p =0.001). Specifically, subgroup analysis indicated significant improvement with caffeine in attack (g = 0.52, p =0.003), serve (g = 0.44, p =0.046) and accuracy (g = 0.68, p =0.001) tasks, but not in the velocity-based tasks (g = 0.26, p =0.168). Moreover, The I² statistics showed low heterogeneity for the studies (I² = 0 - 34.6). Acute caffeine ingestion appears to enhance physical performance in volleyball, with positive effects translating in jump and strength-based tests translated into improved skill execution during volleyball-specific tasks. Further research is needed to refine dosing strategies, account for individual differences based on habitual caffeine intake and player position, and assess long-term outcomes of caffeine intake.