Introduction: Previous research has suggested that caffeine can enhance performance in volleyball. However, most meta-analyses on caffeine supplementation in volleyball have primarily focused on male athletes or mixed-sex samples. To date, no meta-analysis has specifically examined the effects of caffeine in female volleyball players. Therefore, the present study aimed to synthesize the available evidence to provide a cautious and preliminary evaluation of the effects of caffeine on multidimensional performance outcomes in female volleyball athletes. Methods: A systematic search was conducted in March 2026 across PubMed, Web of Science, the Cochrane Library, and ProQuest. The review was registered in PROSPERO (CRD420261355948). Randomized controlled trials examining the effects of caffeine intake on performance in female volleyball players were included. Methodological quality and risk of bias were assessed using the PEDro scale and the RoB 2 tool, and the certainty of evidence was evaluated using the GRADE approach. Results: Five studies were included, comprising a total of 66 female athletes. Overall methodological quality was high, although some risk of bias was identified. According to the GRADE assessment, the overall certainty of evidence was very low. The exploratory meta-analysis did not provide clear evidence supporting an ergogenic effect of caffeine supplementation on sport-specific performance (spike performance), physical performance (jump height, change of direction, handgrip strength, and power output), or physiological outcomes (fatigue- and heart rate-related parameters) in female volleyball players (p>0.05). In addition, caffeine intake was associated with potential adverse effects, including hand tremors, anxiety, and excessive stimulation. Conclusion: Based on the currently limited evidence, acute caffeine ingestion (2-6.4mg/kg) did not show a consistent ergogenic benefit multiple performance outcomes in female volleyball players and may be associated with potential adverse effects, such as hand tremors and anxiety. Therefore, the findings should be interpreted cautiously as preliminary and exploratory evidence rather than as a basis for definitive practical recommendations.
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