Varying doses of evening caffeine ingestion have different effects on rowing ergometer performance, sleep quality, and wakefulness scores

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dc.authorid0000-0001-6092-2849
dc.authorid0000-0001-7767-8416
dc.contributor.authorKarakulak, Izzet
dc.contributor.authorYildirim, Ulas Can
dc.contributor.authorErkan, Dilara
dc.contributor.authorKarayigit, Raci
dc.contributor.authorEyuboglu, Ender
dc.contributor.authorDiedhiou, Azize Bingol
dc.contributor.authorGundem, Mehmet Can
dc.date.accessioned2026-02-03T12:00:04Z
dc.date.available2026-02-03T12:00:04Z
dc.date.issued2025
dc.departmentÇanakkale Onsekiz Mart Üniversitesi
dc.description.abstractIntroduction: This study investigated the dose-dependent effects of evening caffeine ingestion on rowing performance, sleep quality, and daytime sleepiness in trained male rowers. Methods: Using a double-blind, randomized, crossover design, 13 university-level rowers (mean age = 22.07 +/- 2.21 years; mean body mass = 77.66 +/- 6.45 kg) completed four 2,000 m time-trial sessions between 19:00 and 20:00 h under placebo (PLA), low-dose capsule caffeine (3 mg/kg, LDC), moderate-dose capsule caffeine (6 mg/kg, MDC), and high-dose capsule caffeine (9 mg/kg, HDC) conditions. Performance metrics, heart rate, and subjective sleep assessments were collected. Rowing performance was assessed by a standard 2,000 m rowing ergometer (Concept II, United States) time trial. Sleep quality was measured with a numerical rating scale in the morning after each trial, and daytime sleepiness was measured with the Karolinska Sleepiness Scale. Results: Results indicated significantly improved rowing times and power output with HDC and MDC compared to PLA (p < 0.05), with HDC yielding the most notable enhancements (d = 0.40-0.41). However, these ergogenic benefits were accompanied by significantly impaired sleep quality and elevated daytime sleepiness in both HDC and MDC groups (p < 0.01; d = 1.3-1.5). Notably, adverse effects such as headache, insomnia, and gastrointestinal discomfort were predominantly reported in the HDC condition (p < 0.05). Although LDC offered mild performance improvements with minimal sleep disruption, only the high dose condition exhibited large physiological and perceptual trade-offs. Discussion: These findings indicate a clear dose-response relationship, wherein higher evening caffeine intake improves performance but has detrimental effects on sleep and recovery markers. Coaches and athletes should carefully balance caffeine dosing against potential recovery costs, especially in evening training or competition contexts.
dc.identifier.doi10.3389/fnut.2025.1659220
dc.identifier.issn2296-861X
dc.identifier.pmid41477315
dc.identifier.scopus2-s2.0-105026242842
dc.identifier.scopusqualityQ1
dc.identifier.urihttps://doi.org/10.3389/fnut.2025.1659220
dc.identifier.urihttps://hdl.handle.net/20.500.12428/34503
dc.identifier.volume12
dc.identifier.wosWOS:001653379100001
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_20260130
dc.subjectcaffeine
dc.subjectdose-response
dc.subjectrowing performance
dc.subjectsleep quality
dc.subjectwakefulness
dc.titleVarying doses of evening caffeine ingestion have different effects on rowing ergometer performance, sleep quality, and wakefulness scores
dc.typeArticle

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