Datson N, Hulton A, Andersson H, Lewis T, Weston M, Drust B, et al. Applied physiology of female soccer: an update. Sports Med. 2014;44(9):1225–40.
Barnes C, Archer D, Hogg B, Bush M, Bradley P. The evolution of physical and technical performance parameters in the English premier league. Int J Sports Med. 2014;35(13):1095–100.
Rogan S, Schumacher N, Schmidt M, Wellmann K, Braumann K-M. General perceptual-cognitive abilities: age and position in soccer. PLOS ONE. 2018;13(8):e0202627.
Krustrup P, Mohr M, Ellingsgaard H, Bangsbo J. Physical demands during an elite female soccer game: importance of training status. Med Sci Sports Exerc. 2005;37(7):1242.
Naderi A, Earnest CP, Lowery RP, Wilson JM, Willems ME. Co-ingestion of nutritional ergogenic aids and high-intensity exercise performance. Sports Med. 2016;46(10):1407–18.
Tallis J, Clarke N, Morris R, Richardson D, Ellis M, Eyre E, et al. The prevalence and practices of caffeine use as an ergogenic aid in English professional soccer. Biol Sport. 2021;38(1):525.
Barreto G, Grecco B, Merola P, Reis CEG, Gualano B, Saunders B. Novel insights on caffeine supplementation, CYP1A2 genotype, physiological responses and exercise performance. Eur J Appl Physiol. 2021;121:749–69.
Del Coso J, Muñoz-Fernández VE, Muñoz G, Fernández-Elías VE, Ortega JF, Hamouti N, et al. Effects of a caffeine-containing energy drink on simulated soccer performance. PLOS ONE. 2012;7(2):e31380.
Ferreira RES, Pacheco RL, de Oliveira-Cruz-Latorraca C, Riera R, Eid RG, Martimbianco ALC. Effects of caffeine supplementation on physical performance of soccer players: systematic review and meta-analysis. Sports Health. 2021;13:347–58.
Wylie LJ, Mohr M, Krustrup P, Jackman SR, Ermιdis G, Kelly J, et al. Dietary nitrate supplementation improves team sport-specific intense intermittent exercise performance. Eur J Appl Physiol. 2013;113(7):1673–84.
Nyakayiru J, Jonvik K, Trommelen J, Pinckaers P, Senden J, van Loon L, et al. Beetroot juice supplementation improves high-intensity intermittent type exercise performance in trained soccer players. Nutrients. 2017;9(3):314.
López-Samanes Á, Pérez-López A, Moreno-Pérez V, Nakamura FY, Acebes-Sánchez J, Quintana-Milla I, et al. Effects of beetroot juice ingestion on physical performance in highly competitive tennis players. Nutrients. 2020;12(2):584.
López-Samanes Á, Gómez Parra A, Moreno-Pérez V, Courel-Ibáñez J. Does acute beetroot juice supplementation improve neuromuscular performance and match activity in young basketball players? A randomized, placebo-controlled study. Nutrients. 2020;12(1):188.
Rojas-Valverde D, Montoya-Rodríguez J, Azofeifa-Mora C, Sanchez-Urena B. Effectiveness of beetroot juice derived nitrates supplementation on fatigue resistance during repeated-sprints: a systematic review. Crit Rev Food Sci Nutr. 2020;1–12.
Senefeld JW, Wiggins CC, Regimbal RJ, Dominelli PB, Baker SE, Joyner MJ. Ergogenic effect of nitrate supplementation: a systematic review and meta-analysis. Med Sci Sports Exerc. 2020;52(10):2250.
Lane SC, Hawley JA, Desbrow B, Jones AM, Blackwell JR, Ross ML, et al. Single and combined effects of beetroot juice and caffeine supplementation on cycling time trial performance. Appl Physiol Nutr Metab. 2014;39(9):1050–7.
Glaister M, Pattison JR, Muniz-Pumares D, Patterson SD, Foley P. Effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance. J Strength Cond Res. 2015;29(1):165–74.
Handzlik MK, Gleeson M. Likely additive ergogenic effects of combined preexercise dietary nitrate and caffeine ingestion in trained cyclists. ISRN Nutr. 2013;2013:1–8.
Oskarsson J, McGawley K. No individual or combined effects of caffeine and beetroot-juice supplementation during submaximal or maximal running. Appl Physiol Nutr Metab. 2018;43(7):697–703.
Meeusen R, Decroix L. Nutritional supplements and the brain. Int J Sport Nutr Exerc Metab. 2018;28(2):200–11.
Lorenzo Calvo J, Fei X, Domínguez R, Pareja-Galeano H. Caffeine and cognitive functions in sports: a systematic review and meta-analysis. Nutrients. 2021;13(3):868.
Mora-Rodríguez R, Pallarés JG, López-Gullón JM, López-Samanes Á, Fernández-Elías VE, Ortega JF. Improvements on neuromuscular performance with caffeine ingestion depend on the time-of-day. J Sci Med Sport. 2015;18(3):338–42.
Dumar AM, Huntington AF, Rogers RR, Kopec TJ, Williams TD, Ballmann CG. Acute beetroot juice supplementation attenuates morning-associated decrements in supramaximal exercise performance in trained sprinters. Int J Environ Res Public Health. 2021;18(2):412.
Bühler E, Lachenmeier D, Schlegel K, Winkler G. Development of a tool to assess the caffeine intake among teenagers and young adults. Ernahrungs Umschau. 2014;61(4):58–63.
Easton C, Monaghan C, Liddle L, McIlvenna LC, Burleigh M, Muggeridge D, et al., editors. Anti-bacterial mouthwash reduces plasma nitrite following dietary nitrate supplementation but does not alter stress response. In: American college of sports medicine 64th annual meeting: 8th world congress on exercise is medicine® and world congress on the basic science of exercise and the brain; 2017.
Domínguez R, Garnacho-Castaño MV, Cuenca E, García-Fernández P, Muñoz-González A, De Jesús F, et al. Effects of beetroot juice supplementation on a 30-s high-intensity inertial cycle ergometer test. Nutrients. 2017;9(12):1360.
Mason RL, Gunst RF, Hess JL. Statistical design and analysis of experiments: with applications to engineering and science. Hoboken: Wiley; 2003.
Krustrup P, Mohr M, Amstrup T, Rysgaard T, Johansen J, Steensberg A, et al. The yo-yo intermittent recovery test: physiological response, reliability, and validity. Med Sci Sports Exerc. 2003;35(4):697–705.
Mujika I, Santisteban J, Impellizzeri FM, Castagna C. Fitness determinants of success in men’s and women’s football. J Sports Sci. 2009;27(2):107–14.
Koozehchian MS, Earnest CP, Jung YP, Collins PB, O’Connor A, Dalton R, et al. Dose response to one week of supplementation of a multi-ingredient preworkout supplement containing caffeine before exercise. J Caffeine Res. 2017;7(3):81–94.
Pfeiffer B, Cotterill A, Grathwohl D, Stellingwerff T, Jeukendrup AE. The effect of carbohydrate gels on gastrointestinal tolerance during a 16-km run. Int J Sport Nutr Exerc Metab. 2009;19(5):485–503.
Sawilowsky SS. New effect size rules of thumb. J Mod Appl Stat Methods. 2009;8(2):26.
Amrhein V, Korner-Nievergelt F, Roth T. The earth is flat (p > 0.05): significance thresholds and the crisis of unreplicable research. PeerJ. 2017;5:e3544.
Thompson C, Vanhatalo A, Jell H, Fulford J, Carter J, Nyman L, et al. Dietary nitrate supplementation improves sprint and high-intensity intermittent running performance. Nitric Oxide. 2016;61:55–61.
Nyakayiru J, van Loon LJC, Verdijk LB. Could intramuscular storage of dietary nitrate contribute to its ergogenic effect? A mini-review. Free Radic Biol Med. 2020;152:295–300.
Shah I, Petroczi A, James RA, Naughton DP. Determination of nitrate and nitrite content of dietary supplements using ion chromatography. J Anal Bioanal Techn 2013;12(003).
Gallardo EJ, Coggan AR. What is in your beet juice? Nitrate and nitrite content of beet juice products marketed to athletes. Int J Sport Nutr Exerc Metab. 2019;29(4):345–9.
Cermak NM, Gibala MJ, van Loon LJC. Nitrate supplementation’s improvement of 10-km time-trial performance in trained cyclists. Int J Sport Nutr Exerc Metab. 2012;22(1):64–71.
Guest NS, VanDusseldorp TA, Nelson MT, Grgic J, Schoenfeld BJ, Jenkins ND, et al. International society of sports nutrition position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18(1):1–37.
Abian-Vicen J, Puente C, Salinero JJ, González-Millán C, Areces F, Muñoz G, et al. A caffeinated energy drink improves jump performance in adolescent basketball players. Amino Acids. 2014;46(5):1333–41.
Ranchordas MK, King G, Russell M, Lynn A, Russell M. Effects of caffeinated gum on a battery of soccer-specific tests in trained university-standard male soccer players. Int J Sport Nutr Exerc Metab. 2018;28(6):629–34.
Muro N, Parada M. Effect of caffeine on aerobic endurance performance. Mexican J Med Res. 2016;4:8.
Ellis M, Noon M, Myers T, Clarke N. Low doses of caffeine: enhancement of physical performance in elite adolescent male soccer players. Int J Sports Physiol Perform. 2019;14(5):569–75.
Grgic J, Garofolini A, Pickering C, Duncan MJ, Tinsley GM, Del Coso J. Isolated effects of caffeine and sodium bicarbonate ingestion on performance in the Yo–Yo test: a systematic review and meta-analysis. J Sci Med Sport. 2020;23(1):41–7.
Pickering C, Kiely J. Are the current guidelines on caffeine use in sport optimal for everyone? Inter-individual variation in caffeine ergogenicity, and a move towards personalised sports nutrition. Sports Med. 2018;48(1):7–16.
Jones AM, Ferguson SK, Bailey SJ, Vanhatalo A, Poole DC. Fiber type-specific effects of dietary nitrate. Exerc Sport Sci Rev. 2016;44(2):53–60.
San Juan AF, López-Samanes Á, Jodra P, Valenzuela PL, Rueda J, Veiga-Herreros P, et al. Caffeine supplementation improves anaerobic performance and neuromuscular efficiency and fatigue in Olympic-level boxers. Nutrients. 2019;11(9):2120.
Esteves GP, Swinton P, Sale C, James RM, Artioli GG, Roschel H, et al. Individual participant data meta-analysis provides no evidence of intervention response variation in individuals supplementing with beta-alanine. Int J Sport Nutr Exerc Metab. 2021;31(4):305–13.
Doherty M, Smith PM. Effects of caffeine ingestion on rating of perceived exertion during and after exercise: a meta-analysis. Scand J Med Sci Sports. 2005;15(2):69–78.
Lara B, Gonzalez-Millán C, Salinero JJ, Abian-Vicen J, Areces F, Barbero-Alvarez JC, et al. Caffeine-containing energy drink improves physical performance in female soccer players. Amino Acids. 2014;46(5):1385–92.
Lago-Rodríguez Á, Jodra P, Bailey S, Domínguez R. Caffeine improves performance but not duration of the countermovement jump phases. J Sports Med Phys Fitness; 2020.
Sanchez-Medina L, González-Badillo JJ. Velocity loss as an indicator of neuromuscular fatigue during resistance training. Med Sci Sports Exerc. 2011;43(9):1725–34.
Maté-Muñoz JL, Lougedo JH, Barba M, García-Fernández P, Garnacho-Castaño MV, Domínguez R. Muscular fatigue in response to different modalities of CrossFit sessions. PLOS ONE. 2017;12(7):e0181855.
García-Pinillos F, Ramírez-Campillo R, Boullosa D, Jiménez-Reyes P, Latorre-Román PÁ. Vertical jumping as a monitoring tool in endurance runners: a brief review. J Hum Kinet. 2021;80(1):297–308.
Hogervorst E, Riedel W, Jeukendrup A, Jolles J. Cognitive performance after strenuous physical exercise. Percept Mot Skills. 1996;83(2):479–88.
Fery Y, Ferry A, Hofe AV, Rieu M. Effect of physical exhaustion on cognitive functioning. Percept Mot Skills. 1997;84(1):291–8.
Calverley TA, Ogoh S, Marley CJ, Steggall M, Marchi N, Brassard P, et al. HIITing the brain with exercise: mechanisms, consequences and practical recommendations. J Physiol. 2020;598(13):2513–30.
Thompson C, Wylie LJ, Fulford J, Kelly J, Black MI, McDonagh ST, et al. Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise. Eur J Appl Physiol. 2015;115(9):1825–34.
Crowe MJ, Leicht AS, Spinks WL. Physiological and cognitive responses to caffeine during repeated, high-intensity exercise. Int J Sport Nutr Exerc Metab. 2006;16(5):528–44.
Lakens D. Sample size justification. 2021.
Saunders B, de Oliveira LF, da Silva RP, de Salles PV, Gonçalves L, Yamaguchi G, et al. Placebo in sports nutrition: a proof-of-principle study involving caffeine supplementation. Scand J Med Sci Sports. 2017;27(11):1240–7.