Effects of progressive versus consistent dose of caffeine ingestion on volleyball players' exercise performance adaptations following plyometric jump training Head title: Various caffeine doses and volleyball performance

Ganfang ZhuKeqi Fu^*Yangzheng Xie

• Zhejiang Chinese Medical University, Hangzhou, China

The consumption of caffeine (CAF) to enhance adaptations in athletes has been documented in prior studies; however, the identification of an optimal approach for CAF supplementation during short-term interventions remains unclear. This study aimed to investigate how different caffeine (CAF) dosage strategies consumed 1-hour before plyometric jump training (PJT) affect exercise performance adaptations in male volleyball athletes.Methods: A total of thirty-two young volleyball players volunteered for the study and were randomly divided into four groups: 3 mg/kg of caffeine (CAF-3, n=8), 6 mg/kg of caffeine (CAF-6, n=8), progressively increases from 3 to 6 mg/kg of caffeine (CAF-3 to 6, n=8), and placebo (PL, n=8). All athletes engaged in a 4-week PJT intervention, three times a week, and ingested their CAF or PL in a double-blind manner one hour prior to the PJT sessions.Countermovement vertical jump (CMVJ), spike jump (SPJ), block jump (BLJ), 10-m sprint, T-test change of direction speed (T-CODS), maximal strength, and Wingate anaerobic power test were assessed both before and after the training intervention. Results: The CAF-3 to 6 and CAF-6 groups showed more gains (p<0.05) than the CAF-3 and PL groups in the CMVJ (7.6% and 6.9% vs. 4.3% and 4.1%), SPJ (2.5% and 2.3% vs. 1.4% and 1.4%), BLJ (1.1% and 1.0% vs. 0.7% and 0.7%), 10-m sprint (-7.5% and -7.4% vs. -5.2% and -5.0%), T-CODS (-5.4% and -5.2% vs. -3.8% and -3.5%), 1RM strength (5.2% and 5.3% vs. 2.5% and 2.4%), peak power (10.1% and 9.4% vs. 6.2% and 6.0%) and mean power (8.7% and 8.2% vs 5.1% and 4.9%), respectively, following the training period. However, no significant (p>0.05) differences were observed between the CAF-3 to 6 versus CAF-6 in the magnitude of adaptations in the performance of players after training period. Conclusions: In summary, elevated caffeine intake serves as an ergogenic aid to enhance exercise performance adaptations in volleyball athletes. Furthermore, a progressive CAF loading strategy appears to be as effective as maintaining a consistent dosage throughout a 4-week PJT program. This approach presents a viable option for CAF supplementation, potentially attenuating total CAF usage while eliciting similar training benefits.