Acute effects of combined and isolated caffeine and theanine supplementation on physical and cognitive performance in competitive athletes: a randomized, double-blind, placebo-controlled crossover study

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dc.contributor.authorTuncer, Selin Yildirim
dc.contributor.authorOzdenk, Serhat
dc.contributor.authorYildirim, Ulas Can
dc.contributor.authorErkan, Dilara
dc.contributor.authorSari, Cengizhan
dc.contributor.authorGundem, Mehmet Can
dc.contributor.authorSar, Halit
dc.date.accessioned2026-04-25T14:20:26Z
dc.date.available2026-04-25T14:20:26Z
dc.date.issued2026
dc.departmentSinop Üniversitesi
dc.description.abstractIntroduction Modern athletic performance is driven not only by physical capacity but also by rapid decision-making, attentional control, and visuomotor coordination. Evidence regarding the acute effects of caffeine (CAF), L-theanine (TEA), and their combination remains inconsistent, particularly with respect to their combined influence on physical and cognitive performance in athletic populations. This study examined the acute effects of isolated and combined CAF and TEA supplementation on maximal strength, intermittent aerobic endurance, and eye-hand coordination in competitive athletes. It was hypothesized that the combined ingestion of CAF and TEA would differentially affect physical performance and eye-hand coordination outcomes compared with isolated CAF or TEA intake.Methods Twenty trained athletes completed four randomized, double-blind, placebo-controlled crossover conditions: CAF (3 mgkg-1), TEA (200 mg), CAF+TEA (COM), and placebo (CON), with >= 72 h washout. Outcomes included isometric leg, back, and handgrip strength; Yo-Yo Intermittent Endurance Test Level 1 performance; and visuomotor coordination (CogniFit (R)). Data were analyzed using repeated-measures ANOVA with Bonferroni corrections (alpha = 0.05).Results Condition effects were found for leg strength (p = 0.004, eta p2 = 0.24) and back strength (p = 0.008, eta p2 = 0.19). In the COM condition, no additional or synergistic effect on maximal strength was observed. Additionally, no significant difference was found between the conditions in aerobic endurance, maximum isometric handgrip strength, and hand-eye coordination results. Caffeine ingestion did not differ from placebo for any strength outcome under the present conditions. Finally, acute ingestion of TEA was associated with reduced maximal isometric leg and back strength compared with CAF and CON.Discussion Findings challenge the prevailing assumption of CAF + TEA synergy and underscore the need for task-specific interpretation of co-supplementation strategies. Future studies should evaluate dose-response interactions, habitual caffeine intake, sex-specific responses, and broader cognitive domains beyond visuomotor control. The randomized controlled trial was registered at ClinicalTrials.gov, under the registration number NCT07268573.Clinical Trial Registration ClinicalTrials.gov, NCT07268573.
dc.identifier.doi10.3389/fnut.2025.1751673
dc.identifier.issn2296-861X
dc.identifier.pmid41668720
dc.identifier.scopus2-s2.0-105029561405
dc.identifier.scopusqualityN/A
dc.identifier.urihttps://doi.org/10.3389/fnut.2025.1751673
dc.identifier.urihttps://hdl.handle.net/11486/8571
dc.identifier.volume12
dc.identifier.wosWOS:001683972300001
dc.identifier.wosqualityQ1
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.indekslendigikaynakPubMed
dc.language.isoen
dc.publisherFrontiers Media Sa
dc.relation.ispartofFrontiers in Nutrition
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı
dc.rightsinfo:eu-repo/semantics/openAccess
dc.snmzKA_WOS_20260420
dc.subjectcaffeine
dc.subjectcognitive performance
dc.subjectco-supplementation
dc.subjectisometric strength
dc.subjectL-theanine
dc.titleAcute effects of combined and isolated caffeine and theanine supplementation on physical and cognitive performance in competitive athletes: a randomized, double-blind, placebo-controlled crossover study
dc.typeArticle

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