{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T18:29:29Z","timestamp":1787682569182,"version":"build-2784847793"},"reference-count":62,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"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\/Objectives: Repeated sprint performance is typically reduced during the morning because of circadian-related changes in physiological function and muscle strength. Acute caffeine supplementation may attenuate these decrements; however, evidence remains inconsistent. This is partly because of inadequate control of chronobiological and methodological confounders. This study investigated the effects of acute morning caffeine ingestion on repeated sprint performance, physiological responses, strength, power and mood under rigorously standardized chronobiological conditions. Methods: Seventeen recreationally active, low habitual caffeine-consumer males completed six laboratory visits comprising three familiarization sessions and three experimental trials in a performance grouped, randomized for starting condition, counterbalanced, double-blind, placebo-controlled, crossover design. Participants ingested either caffeine (CAFF; 300 mg, 2.5\u20135.3 mg\u00b7kg\u22121), placebo (PLAC) or no-pill control (NoPill) 60 min before testing (07:30 h). Experimental sessions included assessments of mood, caffeine withdrawal symptoms, intra-aural temperature, grip strength, squat jump, countermovement jump and a 10 \u00d7 20 m repeated sprint protocol. Heart rate, ratings of perceived exertion (RPE), thermal comfort, blood lactate and blood glucose were assessed throughout the protocol. Data were analyzed using repeated-measures general linear models. Results: Caffeine did not significantly improve repeated sprint performance compared with PLAC or NoPill, although a trend towards faster 20 m sprint times was observed (3.39 \u00b1 0.19 s vs. 3.43 \u00b1 0.18 s and 3.41 \u00b1 0.19 s, respectively; p = 0.070). Caffeine significantly reduced RPE (p = 0.029) but did not alter heart rate, blood lactate, blood glucose, thermal comfort, intra-aural temperature, mood, sleepiness, caffeine withdrawal symptoms nor lower-body power outcomes. Conclusions: Acute morning ingestion of 300 mg caffeine reduced perceived exertion but did not produce a clear ergogenic effect on repeated sprint performance under rigorously standardized chronobiological conditions. These findings suggest that, in low habitual caffeine users, the central perceptual effects of caffeine are insufficient to overcome the physiological constraints limiting morning repeated sprint performance and highlight the importance of rigorous chronobiological standardization when evaluating nutritional ergogenic aids.<\/jats:p>","DOI":"10.3390\/nu18152541","type":"journal-article","created":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T12:32:43Z","timestamp":1785846763000},"page":"2541","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Effects of Acute Caffeine Ingestion on Morning Strength, Power and Repeated Sprint Measures in Males: A Standardized Approach"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-0707-6001","authenticated-orcid":false,"given":"Sophie J.","family":"Vickery","sequence":"first","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Magali","family":"Giacomoni","sequence":"additional","affiliation":[{"name":"Laboratory Youth Physical Activity Sport and Health (J-AP2S), University of Toulon, 83130 La Garde, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-6225-3471","authenticated-orcid":false,"given":"Jo\u00e3o P. S.","family":"Agulhari","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Theo","family":"Batten","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-3328-4790","authenticated-orcid":false,"given":"Olivia G.","family":"Crozier","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dylan","family":"Goorwappa","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4862-6531","authenticated-orcid":false,"given":"Benoit","family":"Mauvieux","sequence":"additional","affiliation":[{"name":"UR 7480 VERTEX, UFR STAPS, Universit\u00e9 de Caen Normandie (UNICAEN), Normandie Universit\u00e9, 14000 Caen, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7680-3991","authenticated-orcid":false,"given":"Samuel A.","family":"Pullinger","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"},{"name":"Sport Science Department, Inspire Institute of Sport, Vidyanagar, Bellary 583275, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Neil","family":"Chester","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stuart J.","family":"Hesketh","sequence":"additional","affiliation":[{"name":"School of Medicine and Dentistry, University of Lancashire, 135A Adelphi Street, Preston PR1 7BH, Lancashire, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8913-0941","authenticated-orcid":false,"given":"Ben J.","family":"Edwards","sequence":"additional","affiliation":[{"name":"Research Institute for Sport and Exercise Sciences (RISES), John Moores University (Liverpool), Byrom Street, Liverpool L3 3AF, Merseyside, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1007\/s40279-013-0029-x","article-title":"High-intensity interval training, solutions to the programming puzzle: Part I: Cardiopulmonary emphasis","volume":"43","author":"Buchheit","year":"2013","journal-title":"Sports Med."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"741","DOI":"10.2165\/11590560-000000000-00000","article-title":"Repeated-sprint ability\u2014Part II: Recommendations for training","volume":"41","author":"Bishop","year":"2011","journal-title":"Sports Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1025","DOI":"10.2165\/00007256-200535120-00003","article-title":"Physiological and metabolic responses of repeated-sprint activities: Specific to field-based team sports","volume":"35","author":"Spencer","year":"2005","journal-title":"Sports Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1080\/07420528.2019.1703732","article-title":"Time-of-day variation on performance measures in repeated-sprint tests: A systematic review","volume":"37","author":"Pullinger","year":"2020","journal-title":"Chronobiol. Int."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1055\/s-2005-865822","article-title":"Effects of the time of day on repeated all-out cycle performance and short-term recovery patterns","volume":"27","author":"Giacomoni","year":"2006","journal-title":"Int. J. Sports Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1081\/CBI-200041039","article-title":"Circadian rhythms in sports performance\u2014An update","volume":"22","author":"Drust","year":"2005","journal-title":"Chronobiol. Int."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Lok, R., Zerbini, G., Gordijn, M.C.M., Beersma, D.G.M., and Hut, R.A. (2020). Gold, silver or bronze: Circadian variation strongly affects performance in Olympic athletes. Sci. Rep., 10.","DOI":"10.1038\/s41598-020-72573-8"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1080\/07420528.2021.1994585","article-title":"Daily variation in performance measures related to anaerobic power and capacity: A systematic review","volume":"39","author":"Ravindrakumar","year":"2022","journal-title":"Chronobiol. Int."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"292","DOI":"10.2165\/00007256-199621040-00005","article-title":"Circadian variation in sports performance","volume":"21","author":"Atkinson","year":"1996","journal-title":"Sports Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1016\/0031-9384(92)90188-8","article-title":"The circadian rhythm of body temperature","volume":"51","author":"Refinetti","year":"1992","journal-title":"Physiol. Behav."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1062","DOI":"10.1080\/07420520802551568","article-title":"Effect of time of day and partial sleep deprivation on short-term, high-power output","volume":"25","author":"Souissi","year":"2008","journal-title":"Chronobiol. Int."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1984","DOI":"10.1519\/JSC.0b013e31825770a7","article-title":"The effect of training at a specific time of day: A review","volume":"26","author":"Chtourou","year":"2012","journal-title":"J. Strength Cond. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1016\/j.freeradbiomed.2024.08.020","article-title":"The clockwork of champions: Influence of circadian biology on exercise performance","volume":"224","author":"Hesketh","year":"2024","journal-title":"Free Radic. Biol. Med."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Singh, A., and Hesketh, S.J. (2026). Caffeine ingestion improves morning neuromuscular performance to evening levels in healthy females. PLoS ONE, 21.","DOI":"10.1371\/journal.pone.0336199"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Guest, N.S., VanDusseldorp, T.A., Nelson, M.T., Grgic, J., Schoenfeld, B.J., Jenkins, N.D.M., Arent, S.M., Antonio, J., Stout, J.R., and Trexler, E.T. (2021). International society of sports nutrition position stand: Caffeine and exercise performance. J. Int. Soc. Sports Nutr., 18.","DOI":"10.1186\/s12970-020-00383-4"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Agulhari, J.P.S., Chester, N., Giacomoni, M., Gibbons, K.C., Hajdukiewicz, D., O\u2019Brien, H.L., O\u2019Brien, T.D., Jensen, J., Lucas, B., and Moss, S.L. (2026). Effects of Caffeine Ingestion on Morning Cognitive and Muscle Strength Measures in Males: A Standardized Approach. Nutrients, 18.","DOI":"10.3390\/nu18060954"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/S0031-6997(24)01396-6","article-title":"Actions of caffeine in the brain with special reference to factors that contribute to its widespread use","volume":"51","author":"Fredholm","year":"1999","journal-title":"Pharmacol. Rev."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1257","DOI":"10.1038\/nature04284","article-title":"Hypothalamic regulation of sleep and circadian rhythms","volume":"437","author":"Saper","year":"2005","journal-title":"Nature"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"813","DOI":"10.2165\/11317770-000000000-00000","article-title":"Caffeine and anaerobic performance: Ergogenic value and mechanisms of action","volume":"39","author":"Davis","year":"2009","journal-title":"Sports Med."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Xue, R., Huang, J., Chen, B., Ding, L., Guo, L., Cao, Y., and Girard, O. (2025). Effects of Caffeine Dose and Administration Method on Time-Trial Performance: A Systematic Review and Network Meta-Analysis. Nutrients, 17.","DOI":"10.21203\/rs.3.rs-7622430\/v1"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1375","DOI":"10.1249\/MSS.0b013e3181cabbd8","article-title":"Effect of Caffeine Ingestion on Muscular Strength and Endurance: A Meta-Analysis","volume":"42","author":"Mckibaans","year":"2010","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_22","first-page":"245","article-title":"The effect of acute caffeine ingestion on repeated sprint ability in soccer players","volume":"20","author":"Guerra","year":"2021","journal-title":"Braz. J. Exerc. Physiol."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Chen, B., Ding, L., Qin, Q., Lei, T.H., Girard, O., and Cao, Y. (2024). Effect of caffeine ingestion on time trial performance in cyclists: A systematic review and meta-analysis. J. Int. Soc. Sports Nutr., 21.","DOI":"10.1080\/15502783.2024.2363789"},{"key":"ref_24","first-page":"472","article-title":"Effect of caffeine supplementation on repeated sprint running performance","volume":"48","author":"Carr","year":"2008","journal-title":"J. Sports Med. Phys. Fit."},{"key":"ref_25","first-page":"846","article-title":"The Effects of Acute Caffeine Supplementation on Repeated-Sprint Ability in Healthy Young Non-Athletes","volume":"15","author":"Belbis","year":"2022","journal-title":"Int. J. Exerc. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"633","DOI":"10.1139\/apnm-2012-0333","article-title":"Effects of caffeine and carbohydrate mouth rinses on repeated sprint performance","volume":"38","author":"Beaven","year":"2013","journal-title":"Appl. Physiol. Nutr. Metab."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Wang, Y., Su, W., Zhang, S., Zhao, L., Lv, Y., Gu, B., and Yu, L. (2025). Effects of Acute Caffeine Ingestion on Repeated Sprint Ability: A Systematic Review and Meta-Analysis. Nutrients, 17.","DOI":"10.3390\/nu17213475"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.pbb.2019.01.001","article-title":"Effects of caffeine ingestion on the diurnal variation of cognitive and repeated high-intensity performances","volume":"177","author":"Souissi","year":"2019","journal-title":"Pharmacol. Biochem. Behav."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1139\/apnm-2018-0373","article-title":"Can caffeine supplementation reverse the effect of time of day on repeated-sprint exercise performance?","volume":"44","author":"Santos","year":"2019","journal-title":"Appl. Physiol. Nutr. Metab."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Zhang, Y., Yang, W., Xue, Y., Hou, D., Chen, S., Xu, Z., Peng, S., Zhao, H., Wang, C., and Liu, C. (2024). Timing Matters: Time of Day Impacts the Ergogenic Effects of Caffeine-A Narrative Review. Nutrients, 16.","DOI":"10.3390\/nu16101421"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1007\/BF02245489","article-title":"Effects of caffeine, time of day and user history on study-related performance","volume":"109","author":"Mitchell","year":"1992","journal-title":"Psychopharmacology"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1473","DOI":"10.1080\/00140130500101452","article-title":"Gender differences in the circadian variations in muscle strength assessed with and without superimposed electrical twitches","volume":"48","author":"Giacomoni","year":"2005","journal-title":"Ergonomics"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1080\/09291016.2024.2316401","article-title":"Is there a diurnal variation in 4-km cycling time-trial performance, conducted in an environmental chamber where a standardised approach has been employed?","volume":"55","author":"Edwards","year":"2024","journal-title":"Biol. Rhythm Res."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1167","DOI":"10.1080\/07420528.2022.2090373","article-title":"Daily variation on performance measures related to time-trials: A systematic review","volume":"39","author":"Bommasamudram","year":"2022","journal-title":"Chronobiol. Int."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Bruggisser, F., Knaier, R., Roth, R., Wang, W., Qian, J., and Scheer, F.A.J.L. (2023). Best Time of Day for Strength and Endurance Training to Improve Health and Performance? A Systematic Review with Meta-analysis. Sports Med.-Open, 9.","DOI":"10.1186\/s40798-023-00577-5"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"317","DOI":"10.1123\/ijspp.2021-0451","article-title":"Defining training and performance characteristics of elite athletes","volume":"17","author":"McKay","year":"2021","journal-title":"Int. J. Sports Physiol. Perform."},{"key":"ref_37","unstructured":"Nutrition Science Team (2016). Government Dietary Recommendations: Government Recommendations for Energy and Nutrients for Males and Females Aged 1\u201318 Years and 19+ Years, Public Health England."},{"key":"ref_38","first-page":"151","article-title":"College students\u2019 use of caffeine and its relationship to personality","volume":"26","author":"Landrum","year":"1992","journal-title":"Coll. Stud. J."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"588","DOI":"10.1207\/s15327752jpa6703_13","article-title":"Comparison of Beck depression inventories\u2014IA and II in psychiatric outpatients","volume":"67","author":"Beck","year":"1996","journal-title":"J. Personal. Assess."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/0165-1781(89)90047-4","article-title":"The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research","volume":"28","author":"Buysse","year":"1989","journal-title":"Psychiatry Res."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"728","DOI":"10.1037\/0021-9010.74.5.728","article-title":"Evaluation of three circadian rhythm questionnaires with suggestions for an improved measure of morningness","volume":"74","author":"Smith","year":"1989","journal-title":"J. Appl. Psych."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"217","DOI":"10.2165\/00007256-199826040-00002","article-title":"Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine","volume":"26","author":"Atkinson","year":"1998","journal-title":"Sports Med."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Cintra, J.H., Costa-Pereira, J.P., Ripka, W.L., Freire-Correia, M.I., Jesus, F.A., Silva, A.M., Sardinha, L.B., Lohman, T.G., and Heymsfield, S.B. (2026). Skinfolds Measurement Protocols and Standards: A Narrative Review. Adv. Nutr., 17.","DOI":"10.1016\/j.advnut.2026.100662"},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"S\u00e1nchez-S\u00e1nchez, J., Bishop, D., Garc\u00eda-Unanue, J., Ubago-Guisado, E., Hernando, E., L\u00f3pez-Fern\u00e1ndez, J., Colino, E., and Gallardo, L. (2018). Effect of a Repeated Sprint Ability test on the muscle contractile properties in elite futsal players. Sci. Rep., 8.","DOI":"10.1038\/s41598-018-35345-z"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1081\/CBI-120004227","article-title":"A comparison of the suitabilities of rectal, gut, and insulated axilla temperatures for measurement of the circadian rhythm of core temperature in field studies","volume":"19","author":"Edwards","year":"2002","journal-title":"Chronobiol. Int."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/S1469-0292(01)00035-8","article-title":"Construct validity of the profile of Mood States-adolescents for use with adults","volume":"4","author":"Terry","year":"2003","journal-title":"Psychol. Sport Exerc."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"946","DOI":"10.1080\/02640410400000264","article-title":"The stress of travel","volume":"22","author":"Waterhouse","year":"2004","journal-title":"J. Sports Sci."},{"key":"ref_48","first-page":"90","article-title":"Perceived exertion: A note on \u201chistory\u201d and methods","volume":"5","author":"Borg","year":"1973","journal-title":"Med. Sci. Sports"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.drugalcdep.2012.01.009","article-title":"Development of the caffeine withdrawal symptom questionnaire: Caffeine withdrawal symptoms cluster into 7 factors","volume":"124","author":"Juliano","year":"2012","journal-title":"Drug Alcohol Depend."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"901","DOI":"10.1080\/09637486.2017.1320537","article-title":"Caffeine, coffee, and appetite control: A review","volume":"68","author":"Schubert","year":"2017","journal-title":"Int. J. Food Sci. Nutr."},{"key":"ref_51","first-page":"1753","article-title":"Physiological and perceptual responses to self-paced time trials in well-trained cyclists: A comparison of 10 km and 40 km time trials","volume":"117","author":"Gough","year":"2017","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.ptsp.2005.05.004","article-title":"How big does my sample need to be? A primer on the murky world of sample size estimation","volume":"63","author":"Batterham","year":"2005","journal-title":"Phys. Ther. Sport"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"175","DOI":"10.3758\/BF03193146","article-title":"G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciences","volume":"39","author":"Faul","year":"2007","journal-title":"Behav. Res. Methods"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1080\/00480169.2018.1415604","article-title":"P values, p values everywhere!","volume":"66","author":"Hawkins","year":"2018","journal-title":"N. Z. Vet. J."},{"key":"ref_55","unstructured":"Cohen, J. (1988). Statistical Power Analysis for the Behavioral Sciences, Lawrence Erlbaum Associates. [2nd ed.]."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"3","DOI":"10.5114\/biolsport.2021.102930","article-title":"Higher evening metabolic responses contribute to diurnal variation of self-paced cycling performance","volume":"39","author":"Souissi","year":"2021","journal-title":"Biol. Sport"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"673","DOI":"10.2165\/11590550-000000000-00000","article-title":"Repeated-sprint ability\u2014Part I: Factors contributing to fatigue","volume":"41","author":"Girard","year":"2011","journal-title":"Sports Med."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1080\/09291016.2025.2453834","article-title":"Sleep quality, behaviour, disorders prevalence and chronotype in elite junior and senior athletes","volume":"56","author":"Pullinger","year":"2025","journal-title":"Biol. Rhythm Res."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Peng, Y., He, L., Du, W., Liu, B., Wang, X., and Gong, Y. (2026). Does acute caffeine ingestion improve high-intensity interval exercise performance? A systematic review and meta-analysis. Front. Physiol., 17.","DOI":"10.3389\/fphys.2026.1858094"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"330","DOI":"10.1080\/02640414.2015.1052746","article-title":"Caffeine ingestion enhances perceptual responses during intermittent exercise in female team-game players","volume":"34","author":"Ali","year":"2016","journal-title":"J. Sports Sci."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1111\/j.1600-0838.2005.00445.x","article-title":"Effects of caffeine ingestion on rating of perceived exertion during and after exercise: A meta-analysis","volume":"15","author":"Doherty","year":"2005","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"681","DOI":"10.1136\/bjsports-2018-100278","article-title":"Wake up and smell the coffee: Caffeine supplementation and exercise performance-an umbrella review of 21 published meta-analyses","volume":"54","author":"Grgic","year":"2020","journal-title":"Br. J. Sports Med."}],"container-title":["Nutrients"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6643\/18\/15\/2541\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T12:43:48Z","timestamp":1785847428000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6643\/18\/15\/2541"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,4]]},"references-count":62,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["nu18152541"],"URL":"https:\/\/doi.org\/10.3390\/nu18152541","relation":{},"ISSN":["2072-6643"],"issn-type":[{"value":"2072-6643","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,4]]}}}