{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,4]],"date-time":"2026-11-04T02:59:35Z","timestamp":1793761175572,"version":"4.6.1"},"reference-count":67,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2023,9,19]],"date-time":"2023-09-19T00:00:00Z","timestamp":1695081600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background: The improvement of performance and skill indices of volleyball players can affect their success rate. Therefore, the present study aimed to evaluate the effects of acute caffeine supplementation of varied doses on collegiate volleyball players\u2019 specific performance and skills. Method: This research was a randomized, double-blind, crossover design study in which 15 male volleyball players aged 18 to 25 years participated voluntarily. Participants were randomly placed in three different conditions, including 3 mg of caffeine per kilogram of body weight (C3), 6 mg of caffeine per kilogram of body weight (C6), and a placebo (PLA) with a one-week wash-out period between exercise trials. The supplement was taken 60 min before each exercise session. Ball throwing, hand movement speed, agility, Sargent\u2019s jump and handgrip, and attacking and serving skill tests were measured and analyzed to check the performance and skill of the volleyball players. Results: This study showed a significant increase in agility test in C6 compared with the PLA condition (p = 0.02). Additionally, there was a significant improvement in Sargent\u2019s jump in C6 compared with PLA (p = 0.00) and C6 compared with the C3 condition (p = 0.00). Also, attacking skill significantly increased in C3 compared with PLA (p = 0.00) and C6 compared with the PLA condition (p = 0.00). In addition, there was a significant increase in serving skill for C6 compared with PLA (p = 0.00) and C3 (p = 0.00). However, there were no significant differences in hand movement speed (p = 0.06), left handgrip (p = 0.85), right handgrip (p = 0.47), or medicine ball throwing (p = 0.22) between the three conditions. Conclusions: In conclusion, the findings of the current study suggested that a higher dose of caffeine compared with a lower dose may be more effective in movements requiring lower-body explosive power and the ability to change direction. Also, according to the findings, it seems that caffeine can lead to the improvement of complex skills, such as serving and attacking in volleyball.<\/jats:p>","DOI":"10.3390\/nu15184049","type":"journal-article","created":{"date-parts":[[2023,9,19]],"date-time":"2023-09-19T02:47:52Z","timestamp":1695091672000},"page":"4049","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Effects of Different Doses of Caffeine Supplementation on Collegiate Male Volleyball Players\u2019 Specific Performance and Skills: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study"],"prefix":"10.3390","volume":"15","author":[{"given":"Javad","family":"Nemati","sequence":"first","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7585-7592","authenticated-orcid":false,"given":"Mohammad","family":"Hemmatinafar","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1165-4961","authenticated-orcid":false,"given":"Alireza","family":"Niknam","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammad","family":"Nikahd","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Narjes","family":"Zeighami","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Babak","family":"Imanian","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kousar","family":"Safari","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nima","family":"Jahaniboushehri","sequence":"additional","affiliation":[{"name":"Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz 71345, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6572-5809","authenticated-orcid":false,"given":"Katsuhiko","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa 359-1192, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,9,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"758","DOI":"10.1519\/JSC.0b013e31816a8440","article-title":"Relative importance of strength, power, and anthropometric measures to jump performance of elite volleyball players","volume":"22","author":"Sheppard","year":"2008","journal-title":"J. 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