{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T17:05:24Z","timestamp":1792515924663,"version":"4.5.0"},"reference-count":37,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2024,5,7]],"date-time":"2024-05-07T00:00:00Z","timestamp":1715040000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100007480","name":"University of Castilla-La Mancha","doi-asserted-by":"publisher","award":["2023-UNIVERS-11983"],"award-info":[{"award-number":["2023-UNIVERS-11983"]}],"id":[{"id":"10.13039\/501100007480","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100007480","name":"University of Castilla-La Mancha","doi-asserted-by":"publisher","award":["2020-PREDUCLM-16702"],"award-info":[{"award-number":["2020-PREDUCLM-16702"]}],"id":[{"id":"10.13039\/501100007480","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100007480","name":"University of Castilla-La Mancha","doi-asserted-by":"publisher","award":["2023-UNIVERS-11983"],"award-info":[{"award-number":["2023-UNIVERS-11983"]}],"id":[{"id":"10.13039\/501100007480","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100007480","name":"University of Castilla-La Mancha","doi-asserted-by":"publisher","award":["2020-PREDUCLM-16702"],"award-info":[{"award-number":["2020-PREDUCLM-16702"]}],"id":[{"id":"10.13039\/501100007480","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>This study aimed to analyse the placebo effect associated with a high dose of caffeine (9 mg\/kg) on heart rate and its variability and on strength tests. Methods: 18 participants experienced in strength training (19.7 \u00b1 2.3 years; 72.2 \u00b1 15.0 kg; 169.6 \u00b1 9.0 cm) performed two days of trials (caffeine-informed\/placebo-ingested (placebo) and non-ingested (control)). Firstly, heart rate and its variability were measured while participants lay down for 15 min. After that, bench press and squat tests were performed at 3 different loads (50%, 75% and 90% of 1RM). Perception of performance, effort and side effects were also evaluated. Results: no differences were found in the vast majority of strength variables analysed. Resting heart rate decreased in the placebo trial (60.39 \u00b1 10.18 bpm control vs. 57.56 \u00b1 9.50 bpm placebo, p = 0.040), and mean RR increased (1020.1 \u00b1 172.9 ms control vs. 1071.5 \u00b1 185.7 ms placebo, p = 0.032). Heart rate variability and perception of performance and effort were similar between conditions (p &gt; 0.05 in all cases). Side effects such as activeness and nervousness were reported while consuming the placebo. Conclusions: the placebo effect did not modify performance in the majority of the strength test variables, HRV and perception of performance and effort. However, resting heart rate was reduced, mean RR increased, and some side effects appeared in the placebo trial.<\/jats:p>","DOI":"10.3390\/nu16101405","type":"journal-article","created":{"date-parts":[[2024,5,7]],"date-time":"2024-05-07T11:00:10Z","timestamp":1715079610000},"page":"1405","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Placebo Effect of Caffeine on Physiological Parameters and Physical Performance"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-2930-829X","authenticated-orcid":false,"given":"David","family":"Ortiz-S\u00e1nchez","sequence":"first","affiliation":[{"name":"Performance and Sport Rehabilitation Laboratory (DEPORSALUD), Faculty of Sports Sciences, University of Castilla-La Mancha, Avenida Carlos III s\/n, 45071 Toledo, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0476-066X","authenticated-orcid":false,"given":"Alfredo","family":"Bravo-S\u00e1nchez","sequence":"additional","affiliation":[{"name":"Performance and Sport Rehabilitation Laboratory (DEPORSALUD), Faculty of Sports Sciences, University of Castilla-La Mancha, Avenida Carlos III s\/n, 45071 Toledo, Spain"},{"name":"Faculty of Health Sciences, Universidad Francisco de Vitoria, 28223 Pozuelo de Alarc\u00f3n, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7898-1254","authenticated-orcid":false,"given":"Mar\u00eda","family":"Ram\u00edrez-delaCruz","sequence":"additional","affiliation":[{"name":"Performance and Sport Rehabilitation Laboratory (DEPORSALUD), Faculty of Sports Sciences, University of Castilla-La Mancha, Avenida Carlos III s\/n, 45071 Toledo, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pablo","family":"Abi\u00e1n","sequence":"additional","affiliation":[{"name":"Performance and Sport Rehabilitation Laboratory (DEPORSALUD), Faculty of Sports Sciences, University of Castilla-La Mancha, Avenida Carlos III s\/n, 45071 Toledo, Spain"},{"name":"Faculty of Humanities and Social Sciences, Comillas Pontifical University, Calle. Alberto Aguilera 23, 28049 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9635-3289","authenticated-orcid":false,"given":"Javier","family":"Abi\u00e1n-Vic\u00e9n","sequence":"additional","affiliation":[{"name":"Performance and Sport Rehabilitation Laboratory (DEPORSALUD), Faculty of Sports Sciences, University of Castilla-La Mancha, Avenida Carlos III s\/n, 45071 Toledo, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,5,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1123\/ijsnem.2017-0429","article-title":"Athletes and Supplements: Prevalence and Perspectives","volume":"28","author":"Garthe","year":"2018","journal-title":"Int. J. Sport. Nutr. Exerc. 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