Much research has been done in sports nutrition in recent years as the demand for performance-enhancing substances increases. Higher intake of nitrates from the diet can increase the bioavailability of nitric oxide (NO) via the nitrate-nitrite-NO pathway. Nevertheless, the increased availability of NO does not always lead to improved performance in some individuals. This review aims to evaluate the relationship between the athlete's training status and the change in time trial performance after increased dietary nitrate intake. Articles indexed by Scopus and PubMed published from 2015 to 2019 were reviewed. Thirteen articles met the eligibility criteria: clinical trial studies on healthy participants with different training status (according to VO2max), conducting time trial tests after dietary nitrate supplementation. The PRISMA guidelines were followed to process the review. We found a statistically significant relationship between VO2max and ergogenicity in time trial performance using one-way ANOVA (p = 0.001) in less-trained athletes (VO2 < 55 mL/kg/min). A strong positive correlation was observed in experimental situations using a chronic supplementation protocol but not in acute protocol situations. In the context of our results and recent histological observations of muscle fibres, there might be a fibre-type specific role in nitric oxide production and, therefore, supplement of ergogenicity.

Faculty of Sports Studies Masaryk University Kamenice 5 625 00 Brno Czech Republic

See more in PubMed

Jones A.M., Thompson C., Wylie L.J., Vanhatalo A. Dietary nitrate and physical performance. Annu. Rev. Nutr. 2018;38:303–328. doi: 10.1146/annurev-nutr-082117-051622. PubMed DOI

Murad F. Discovery of some of the biological effects of nitric oxide and its role in cell signaling. Biosci. Rep. 1999;19:133–154. doi: 10.1023/A:1020265417394. PubMed DOI

Ignarro L.J. Nitric oxide: A unique endogenous signaling molecule in vascular biology. Biosci. Rep. 1999;19:51–71. doi: 10.1023/A:1020150124721. PubMed DOI

Furchgott R.F. Endothelium-derived relaxing factor: Discovery, early studies, and identification as nitric oxide. Biosci. Rep. 1999;19:235–251. doi: 10.1023/A:1020537506008. PubMed DOI

Clifford T., Howatson G., West D.J., Stevenson E.J. The potential benefits of red beetroot supplementation in health and disease. Nutrients. 2015;7:2801–2822. doi: 10.3390/nu7042801. PubMed DOI PMC

Burke L.M. Practical issues in evidence-based use of performance supplements: Supplement interactions, repeated use and individual responses. Sports Med. 2017;47:79–100. doi: 10.1007/s40279-017-0687-1. PubMed DOI PMC

Peeling P., Castell L.M., Derave W., de Hon O., Burke L.M. Sports foods and dietary supplements for optimal function and performance enhancement in track-and-field athletes. Int. J. Sport Nutr. Exerc. Metab. 2019;29:198–209. doi: 10.1123/ijsnem.2018-0271. PubMed DOI

Vitale K., Getzin A. Nutrition and supplement update for the endurance athlete: Review and recommendations. Nutrients. 2019;11:1289. doi: 10.3390/nu11061289. PubMed DOI PMC

Hord N.G., Tang Y., Bryan N.S. Food sources of nitrates and nitrites: The physiologic context for potential health benefits. Am. J. Clin. Nutr. 2009;90:1–10. doi: 10.3945/ajcn.2008.27131. PubMed DOI

Jonvik K.L., Nyakayiru J., van Loon L.J.C., Verdijk L.B. Can elite athletes benefit from dietary nitrate supplementation? J. Appl. Physiol. 2015;119:759–761. doi: 10.1152/japplphysiol.00232.2015. PubMed DOI

Murad F. Nitric oxide and cyclic GMP in cell signaling and drug development. N. Engl. J. Med. 2006;355:2003–2011. doi: 10.1056/NEJMsa063904. PubMed DOI

Rhodes P.M., Leone A.M., Francis P.L., Struthers A.D., Moncada S. The L-arginine: Nitric oxide pathway is the major source of plasma nitrite in fasted humans. Biochem. Biophys. Res. Commun. 1995;209:590–596. doi: 10.1006/bbrc.1995.1541. PubMed DOI

Lundberg J.O., Carlström M., Larsen F.J., Weitzberg E. Roles of dietary inorganic nitrate in cardiovascular health and disease. Cardiovasc. Res. 2011;89:525–532. doi: 10.1093/cvr/cvq325. PubMed DOI

Kapil V., Weitzberg E., Lundberg J.O., Ahluwalia A. Clinical evidence demonstrating the utility of inorganic nitrate in cardiovascular health. Nitric Oxide. 2014;38:45–57. doi: 10.1016/j.niox.2014.03.162. PubMed DOI

Lidder S., Webb A.J. Vascular effects of dietary nitrate (as found in green leafy vegetables and beetroot) via the nitrate-nitrite-nitric oxide pathway. Br. J. Clin. Pharmacol. 2013;75:677–696. doi: 10.1111/j.1365-2125.2012.04420.x. PubMed DOI PMC

Duncan C., Dougall H., Johnston P., Green S., Brogan R., Leifert C., Smith L., Golden M., Benjamin N. Chemical generation of nitric oxide in the mouth from the enterosalivary circulation of dietary nitrate. Nat. Med. 1995;1:546. doi: 10.1038/nm0695-546. PubMed DOI

Benjamin N., O’Driscoll F., Dougall H., Duncan C., Smith L., Golden M., McKenzie H. Stomach NO synthesis. Nature. 1994;368:502. doi: 10.1038/368502a0. PubMed DOI

James P.E., Willis G.R., Allen J.D., Winyard P.G., Jones A.M. Nitrate pharmacokinetics: Taking note of the difference. Nitric Oxide. 2015;48:44–50. doi: 10.1016/j.niox.2015.04.006. PubMed DOI

Lundberg J.O., Weitzberg E. NO generation from inorganic nitrate and nitrite: Role in physiology, nutrition and therapeutics. Arch. Pharm. Res. 2009;32:1119–1126. doi: 10.1007/s12272-009-1803-z. PubMed DOI

Domínguez R., Maté-Muñoz J.L., Cuenca E., García-Fernández P., Mata-Ordoñez F., Lozano-Estevan M.C., Veiga-Herreros P., da Silva S.F., Garnacho-Castaño M.V. Effects of beetroot juice supplementation on intermittent high-intensity exercise efforts. J. Int. Soc. Sports Nutr. 2018;15:2. doi: 10.1186/s12970-017-0204-9. PubMed DOI PMC

Moncada S., Higgs A. The L-arginine-nitric oxide pathway. N. Engl. J. Med. 1993;329:2002–2012. doi: 10.1056/NEJM199312303292706. PubMed DOI

Larsen F.J., Schiffer T.A., Borniquel S., Sahlin K., Ekblom B., Lundberg J.O., Weitzberg E. Dietary inorganic nitrate improves mitochondrial efficiency in humans. Cell Metab. 2011;13:149–159. doi: 10.1016/j.cmet.2011.01.004. PubMed DOI

Sarti P., Forte E., Mastronicola D., Giuffrè A., Arese M. Cytochrome c oxidase and nitric oxide in action: Molecular mechanisms and pathophysiological implications. Biochim. Biophys. Acta. 2012;1817:610–619. doi: 10.1016/j.bbabio.2011.09.002. PubMed DOI

Van Faassen E.E., Bahrami S., Feelisch M., Hogg N., Kelm M., Kim-Shapiro D.B., Kozlov A.V., Li H., Lundberg J.O., Mason R., et al. Nitrite as regulator of hypoxic signaling in mammalian physiology. Med. Res. Rev. 2009;29:683–741. doi: 10.1002/med.20151. PubMed DOI PMC

Bailey S.J., Fulford J., Vanhatalo A., Winyard P.G., Blackwell J.R., DiMenna F.J., Wilkerson D.P., Benjamin N., Jones A.M. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. J. Appl. Physiol. 2010;109:135–148. doi: 10.1152/japplphysiol.00046.2010. PubMed DOI

Coggan A.R., Peterson L.R. Dietary nitrate enhances the contractile properties of human skeletal muscle. Exerc. Sport Sci. Rev. 2018;46:254–261. doi: 10.1249/JES.0000000000000167. PubMed DOI PMC

Rokkedal-Lausch T., Franch J., Poulsen M.K., Thomsen L.P., Weitzberg E., Kamavuako E.N., Karbing D.S., Larsen R.G. Chronic high-dose beetroot juice supplementation improves time trial performance of well-trained cyclists in normoxia and hypoxia. Nitric Oxide Biol. Chem. 2019;85:44–52. doi: 10.1016/j.niox.2019.01.011. PubMed DOI

Wylie L.J., Kelly J., Bailey S.J., Blackwell J.R., Skiba P.F., Winyard P.G., Jeukendrup A.E., Vanhatalo A., Jones A.M. Beetroot juice and exercise: Pharmacodynamic and dose-response relationships. J. Appl. Physiol. 2013;115:325–336. doi: 10.1152/japplphysiol.00372.2013. PubMed DOI

Hoon M.W., Jones A.M., Johnson N.A., Blackwell J.R., Broad E.M., Lundy B., Rice A.J., Burke L.M. The effect of variable doses of inorganic nitrate-rich beetroot juice on simulated 2,000-m rowing performance in trained athletes. Int. J. Sports Physiol. Perform. 2014;9:615–620. doi: 10.1123/ijspp.2013-0207. PubMed DOI

Vanhatalo A., Bailey S.J., Blackwell J.R., DiMenna F.J., Pavey T.G., Wilkerson D.P., Benjamin N., Winyard P.G., Jones A.M. Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2010;299:R1121–R1131. doi: 10.1152/ajpregu.00206.2010. PubMed DOI

Wylie L.J., Ortiz de Zevallos J., Isidore T., Nyman L., Vanhatalo A., Bailey S.J., Jones A.M. Dose-dependent effects of dietary nitrate on the oxygen cost of moderate-intensity exercise: Acute vs. chronic supplementation. Nitric Oxide. 2016;57:30–39. doi: 10.1016/j.niox.2016.04.004. PubMed DOI

Thompson K.G., Turner L., Prichard J., Dodd F., Kennedy D.O., Haskell C., Blackwell J.R., Jones A.M. Influence of dietary nitrate supplementation on physiological and cognitive responses to incremental cycle exercise. Respir. Physiol. Neurobiol. 2014;193:11–20. doi: 10.1016/j.resp.2013.12.015. PubMed DOI

Muggeridge D.J., Sculthorpe N., Grace F.M., Willis G., Thornhill L., Weller R.B., James P.E., Easton C. Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists. Nitric Oxide. 2015;48:3–9. doi: 10.1016/j.niox.2014.09.158. PubMed DOI

Hernández A., Schiffer T.A., Ivarsson N., Cheng A.J., Bruton J.D., Lundberg J.O., Weitzberg E., Westerblad H. Dietary nitrate increases tetanic [Ca2+]i and contractile force in mouse fast-twitch muscle. J. Physiol. 2012;590:3575–3583. doi: 10.1113/jphysiol.2012.232777. PubMed DOI PMC

Haider G., Folland J.P. Nitrate supplementation enhances the contractile properties of human skeletal muscle. Med. Sci. Sports Exerc. 2014;46:2234–2243. doi: 10.1249/MSS.0000000000000351. PubMed DOI

Whitfield J., Gamu D., Heigenhauser G.J.F., van Loon L.J.C., Spriet L.L., Tupling A.R., Holloway G.P. Beetroot juice increases human muscle force without changing Ca2+-handling proteins. Med. Sci. Sports Exerc. 2017;49:2016–2024. doi: 10.1249/MSS.0000000000001321. PubMed DOI

Jones A.M., Ferguson S.K., Bailey S.J., Vanhatalo A., Poole D.C. Fiber Type-Specific Effects of Dietary Nitrate. Exerc. Sport Sci. Rev. 2016;44:53. doi: 10.1249/JES.0000000000000074. PubMed DOI

Sussman I., Erecińska M., Wilson D.F. Regulation of cellular energy metabolism. The Crabtree effect. Biochim. Biophys. Acta Bioenerg. 1980;591:209–223. doi: 10.1016/0005-2728(80)90153-X. PubMed DOI

Nourry C., Fabre C., Bart F., Grosbois J.-M., Berthoin S., Mucci P. Evidence of exercise-induced arterial hypoxemia in prepubescent trained children. Pediatr. Res. 2004;55:674–681. doi: 10.1203/01.PDR.0000114481.58902.FB. PubMed DOI

Lundberg J.O., Weitzberg E. NO-synthase independent NO generation in mammals. Biochem. Biophys. Res. Commun. 2010;396:39–45. doi: 10.1016/j.bbrc.2010.02.136. PubMed DOI

Modin A., Björne H., Herulf M., Alving K., Weitzberg E., Lundberg J.O. Nitrite-derived nitric oxide: A possible mediator of “acidic-metabolic” vasodilation. Acta Physiol. Scand. 2001;171:9–16. doi: 10.1046/j.1365-201x.2001.171001009.x. PubMed DOI

Lundberg J.O., Weitzberg E., Gladwin M.T. The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics. Nat. Rev. Drug Discov. 2008;7:156–167. doi: 10.1038/nrd2466. PubMed DOI

Behnke B.J., McDonough P., Padilla D.J., Musch T.I., Poole D.C. Oxygen exchange profile in rat muscles of contrasting fibre types. J. Physiol. 2003;549:597–605. doi: 10.1113/jphysiol.2002.035915. PubMed DOI PMC

McDonough P., Behnke B.J., Padilla D.J., Musch T.I., Poole D.C. Control of microvascular oxygen pressures in rat muscles comprised of different fibre types. J. Physiol. 2005;563:903–913. doi: 10.1113/jphysiol.2004.079533. PubMed DOI PMC

Ferreira L.F., McDonough P., Behnke B.J., Musch T.I., Poole D.C. Blood flow and O2 extraction as a function of O2 uptake in muscles composed of different fiber types. Respir. Physiol. Neurobiol. 2006;153:237–249. doi: 10.1016/j.resp.2005.11.004. PubMed DOI

Vanin A.F., Bevers L.M., Slama-Schwok A., van Faassen E.E. Nitric oxide synthase reduces nitrite to NO under anoxia. Cell. Mol. Life Sci. 2007;64:96–103. doi: 10.1007/s00018-006-6374-2. PubMed DOI PMC

Bailey S.J., Varnham R.L., DiMenna F.J., Breese B.C., Wylie L.J., Jones A.M. Inorganic nitrate supplementation improves muscle oxygenation, O₂ uptake kinetics, and exercise tolerance at high but not low pedal rates. J. Appl. Physiol. 2015;118:1396–1405. doi: 10.1152/japplphysiol.01141.2014. PubMed DOI

Coggan A.R., Leibowitz J.L., Kadkhodayan A., Thomas D.P., Ramamurthy S., Spearie C.A., Waller S., Farmer M., Peterson L.R. Effect of acute dietary nitrate intake on maximal knee extensor speed and power in healthy men and women. Nitric Oxide. 2015;48:16–21. doi: 10.1016/j.niox.2014.08.014. PubMed DOI PMC

Cermak N.M., Res P., Stinkens R., Lundberg J.O., Gibala M.J., van Loon L.J.C. No improvement in endurance performance after a single dose of beetroot juice. Int. J. Sport Nutr. Exerc. Metab. 2012;22:470–478. doi: 10.1123/ijsnem.22.6.470. PubMed DOI

Christensen P.M., Nyberg M., Bangsbo J. Influence of nitrate supplementation on VO₂ kinetics and endurance of elite cyclists. Scand. J. Med. Sci. Sports. 2013;23:e21–e31. doi: 10.1111/sms.12005. PubMed DOI

Mosher S.L., Gough L.A., Deb S., Saunders B., Naughton L.R.M., Brown D.R., Sparks S.A. High dose Nitrate ingestion does not improve 40 km cycling time trial performance in trained cyclists. Res. Sports Med. 2020;28:138–146. doi: 10.1080/15438627.2019.1586707. PubMed DOI

Boorsma R.K., Whitfield J., Spriet L.L. Beetroot juice supplementation does not improve performance of elite 1500-m runners. Med. Sci. Sports Exerc. 2014;46:2326–2334. doi: 10.1249/MSS.0000000000000364. PubMed DOI

Bescós R., Ferrer-Roca V., Galilea P.A., Roig A., Drobnic F., Sureda A., Martorell M., Cordova A., Tur J.A., Pons A. Sodium nitrate supplementation does not enhance performance of endurance athletes. Med. Sci. Sports Exerc. 2012;44:2400–2409. doi: 10.1249/MSS.0b013e3182687e5c. PubMed DOI

Peacock O., Tjønna A.E., James P., Wisløff U., Welde B., Böhlke N., Smith A., Stokes K., Cook C., Sandbakk Ø. Dietary nitrate does not enhance running performance in elite cross-country skiers. Med. Sci. Sports Exerc. 2012;44:2213–2219. doi: 10.1249/MSS.0b013e3182640f48. PubMed DOI

Coyle E.F., Feltner M.E., Kautz S.A., Hamilton M.T., Montain S.J., Baylor A.M., Abraham L.D., Petrek G.W. Physiological and biomechanical factors associated with elite endurance cycling performance. Med. Sci. Sports Exerc. 1991;23:93–107. doi: 10.1249/00005768-199101000-00015. PubMed DOI

Jeukendrup A.E., Craig N.P., Hawley J.A. The bioenergetics of world class cycling. J. Sci. Med. Sport. 2000;3:414–433. doi: 10.1016/S1440-2440(00)80008-0. PubMed DOI

Yan Z., Okutsu M., Akhtar Y.N., Lira V.A. Regulation of exercise-induced fiber type transformation, mitochondrial biogenesis, and angiogenesis in skeletal muscle. J. Appl. Physiol. 2010;110:264–274. doi: 10.1152/japplphysiol.00993.2010. PubMed DOI PMC

Peeling P., Cox G.R., Bullock N., Burke L.M. Beetroot juice improves on-water 500 M time-trial performance, and laboratory-based paddling economy in national and international-level kayak athletes. Int. J. Sport Nutr. Exerc. Metab. 2015;25:278–284. doi: 10.1123/ijsnem.2014-0110. PubMed DOI

Muggeridge D.J., Howe C.C.F., Spendiff O., Pedlar C., James P.E., Easton C. The effects of a single dose of concentrated beetroot juice on performance in trained flatwater kayakers. Int. J. Sport Nutr. Exerc. Metab. 2013;23:498–506. doi: 10.1123/ijsnem.23.5.498. PubMed DOI

Johnson M.A., Polgar J., Weightman D., Appleton D. Data on the distribution of fibre types in thirty-six human muscles. An autopsy study. J. Neurol. Sci. 1973;18:111–129. doi: 10.1016/0022-510X(73)90023-3. PubMed DOI

Polgar J., Johnson M.A., Weightman D., Appleton D. Data on fibre size in thirty-six human muscles: An autopsy study. J. Neurol. Sci. 1973;19:307–318. doi: 10.1016/0022-510X(73)90094-4. PubMed DOI

Jennekens F.G.I., Tomlinson B.E., Walton J.N. The sizes of the two main histochemical fibre types in five limb muscles in man: An autopsy study. J. Neurol. Sci. 1971;13:281–292. doi: 10.1016/0022-510X(71)90033-5. PubMed DOI

Roth W., Schwanitz P., Pas P., Bauer P. Force-time characteristics of the rowing stroke and corresponding physiological muscle adaptations. Int. J. Sports Med. 1993;14:S32–S34. doi: 10.1055/s-2007-1021221. PubMed DOI

Shephard R.J. Science and medicine of canoeing and kayaking. Sports Med. 1987;4:19–33. doi: 10.2165/00007256-198704010-00003. PubMed DOI

Steinacker J. Physiological aspects of training in rowing. Int. J. Sports Med. 1993;14(Suppl. 1):S3. PubMed

Wylie L.J., Park J.W., Vanhatalo A., Kadach S., Black M.I., Stoyanov Z., Schechter A.N., Jones A.M., Piknova B. Human skeletal muscle nitrate store: Influence of dietary nitrate supplementation and exercise. J. Physiol. 2019;597:5565–5576. doi: 10.1113/JP278076. PubMed DOI PMC

Bryan N.S., Ivy J.L. Inorganic nitrite and nitrate: Evidence to support consideration as dietary nutrients. Nutr. Res. 2015;35:643–654. doi: 10.1016/j.nutres.2015.06.001. PubMed DOI

Porcelli S., Ramaglia M., Bellistri G., Pavei G., Pugliese L., Montorsi M., Rasica L., Marzorati M. Aerobic fitness affects the exercise performance responses to nitrate supplementation. Med. Sci. Sports Exerc. 2015;47:1643–1651. doi: 10.1249/MSS.0000000000000577. PubMed DOI

Tesch P.A., Karlsson J. Muscle fiber types and size in trained and untrained muscles of elite athletes. J. Appl. Physiol. 1985;59:1716–1720. doi: 10.1152/jappl.1985.59.6.1716. PubMed DOI

Proctor D.N., Sinning W.E., Walro J.M., Sieck G.C., Lemon P.W. Oxidative capacity of human muscle fiber types: Effects of age and training status. J. Appl. Physiol. 1995;78:2033–2038. doi: 10.1152/jappl.1995.78.6.2033. PubMed DOI

McQuillan J.A., Dulson D.K., Laursen P.B., Kilding A.E. Dietary nitrate fails to improve 1 and 4 km cycling performance in highly trained cyclists. Int. J. Sport Nutr. Exerc. Metab. 2017;27:255–263. doi: 10.1123/ijsnem.2016-0212. PubMed DOI

Liberati A., Altman D.G., Tetzlaff J., Mulrow C., Gøtzsche P.C., Ioannidis J.P.A., Clarke M., Devereaux P.J., Kleijnen J., Moher D. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: Explanation and elaboration. PLoS Med. 2009;6:e1000100. doi: 10.1371/journal.pmed.1000100. PubMed DOI PMC

De Pauw K., Roelands B., Cheung S.S., De Geus B., Rietjens G., Meeusen R. Guidelines to classify subject groups in sport-science research. Int. J. Sports Physiol. Perform. 2013;8:111–122. doi: 10.1123/ijspp.8.2.111. PubMed DOI

Decroix L., Pauw K.D., Foster C., Meeusen R. Guidelines to classify female subject groups in sport-science research. Int. J. Sports Physiol. Perform. 2016;11:204–213. doi: 10.1123/ijspp.2015-0153. PubMed DOI

Jo E., Fischer M., Auslander A.T., Beigarten A., Daggy B., Hansen K., Kessler L., Osmond A., Wang H., Wes R. The effects of multi-day vs. single pre-exercise nitrate supplement dosing on simulated cycling time trial performance and skeletal muscle oxygenation. J. Strength Cond. Res. 2019;33:217–224. doi: 10.1519/JSC.0000000000001958. PubMed DOI

Maher C.G., Sherrington C., Herbert R.D., Moseley A.M., Elkins M. Reliability of the PEDro scale for rating quality of randomized controlled trials. Phys. Ther. 2003;83:713–721. doi: 10.1093/ptj/83.8.713. PubMed DOI

Verhagen A.P., de Vet H.C., de Bie R.A., Kessels A.G., Boers M., Bouter L.M., Knipschild P.G. The Delphi list: A criteria list for quality assessment of randomized clinical trials for conducting systematic reviews developed by Delphi consensus. J. Clin. Epidemiol. 1998;51:1235–1241. doi: 10.1016/S0895-4356(98)00131-0. PubMed DOI

Glaister M., Pattison J.R., Muniz-Pumares D., Patterson S.D., Foley P. Effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance. J. Strength Cond. Res. 2015;29:165–174. doi: 10.1519/JSC.0000000000000596. PubMed DOI

Callahan M.J., Parr E.B., Hawley J.A., Burke L.M. Single and combined effects of beetroot crystals and sodium bicarbonate on 4-km cycling time trial performance. Int. J. Sport Nutr. Exerc. Metab. 2017;27:271–278. doi: 10.1123/ijsnem.2016-0228. PubMed DOI

Sandbakk S.B., Sandbakk Ø., Peacock O., James P., Welde B., Stokes K., Böhlke N., Tjønna A.E. Effects of acute supplementation of L-arginine and nitrate on endurance and sprint performance in elite athletes. Nitric Oxide Biol. Chem. 2015;48:10–15. doi: 10.1016/j.niox.2014.10.006. PubMed DOI

Nyakayiru J.M., Jonvik K.L., Pinckaers P.J.M., Senden J., van Loon L.J.C., Verdijk L.B. No effect of acute and 6-day nitrate supplementation on VO2 and time-trial performance in highly trained cyclists. Int. J. Sport Nutr. Exerc. Metab. 2017;27:11–17. doi: 10.1123/ijsnem.2016-0034. PubMed DOI

Oskarsson J., McGawley K. No individual or combined effects of caffeine and beetrootjuice supplementation during submaximal or maximal running. Appl. Physiol. Nutr. Metab. 2018;43:697–703. doi: 10.1139/apnm-2017-0547. PubMed DOI

McQuillan J.A., Dulson D.K., Laursen P.B., Kilding A.E. The effect of dietary nitrate supplementation on physiology and performance in trained cyclists. Int. J. Sports Physiol. Perform. 2017;12:684–689. doi: 10.1123/ijspp.2016-0202. PubMed DOI

Shannon O.M., Barlow M.J., Duckworth L., Williams E., Wort G., Woods D., Siervo M., O’Hara J.P. Dietary nitrate supplementation enhances short but not longer duration running time-trial performance. Eur. J. Appl. Physiol. 2017;117:775–785. doi: 10.1007/s00421-017-3580-6. PubMed DOI

de Castro T.F., Manoel F.A., Figueiredo D.H., Figueiredo D.H., Machado F.A. Effect of beetroot juice supplementation on 10-km performance in recreational runners. Appl. Physiol. Nutr. Metab. 2019;44:90–94. doi: 10.1139/apnm-2018-0277. PubMed DOI

McMahon N.F., Leveritt M.D., Pavey T.G. The effect of dietary nitrate supplementation on endurance exercise performance in healthy adults: A systematic review and meta-analysis. Sports Med. 2017;47:735–756. doi: 10.1007/s40279-016-0617-7. PubMed DOI

Hoon M.W., Johnson N.A., Chapman P.G., Burke L.M. The effect of nitrate supplementation on exercise performance in healthy individuals: A systematic review and meta-analysis. Int. J. Sport Nutr. Exerc. Metab. 2013;23:522–532. doi: 10.1123/ijsnem.23.5.522. PubMed DOI

Nyakayiru J., van Loon L.C., Verdijk L. Could intramuscular storage of dietary nitrate contribute to its ergogenic effect? A mini-review. Free Radic. Biol. Med. 2020 doi: 10.1016/j.freeradbiomed.2020.03.025. PubMed DOI

Murray A.J., Horscroft J.A. Mitochondrial function at extreme high altitude. J. Physiol. 2016;594:1137–1149. doi: 10.1113/JP270079. PubMed DOI PMC

Murray A.J. Metabolic adaptation of skeletal muscle to high altitude hypoxia: How new technologies could resolve the controversies. Genome Med. 2009;1:117. doi: 10.1186/gm117. PubMed DOI PMC

Kelly J., Vanhatalo A., Bailey S.J., Wylie L.J., Tucker C., List S., Winyard P.G., Jones A.M. Dietary nitrate supplementation: Effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2014;307:R920–R930. doi: 10.1152/ajpregu.00068.2014. PubMed DOI

Masschelein E., van Thienen R., Wang X., van Schepdael A., Thomis M., Hespel P. Dietary nitrate improves muscle but not cerebral oxygenation status during exercise in hypoxia. J. Appl. Physiol. 2012;113:736–745. doi: 10.1152/japplphysiol.01253.2011. PubMed DOI

Shannon O.M., Duckworth L., Barlow M.J., Deighton K., Matu J., Williams E.L., Woods D., Xie L., Stephan B.C.M., Siervo M., et al. Effects of dietary nitrate supplementation on physiological responses, cognitive function, and exercise performance at moderate and very-high simulated altitude. Front. Physiol. 2017;8 doi: 10.3389/fphys.2017.00401. PubMed DOI PMC

Shannon O.M., Duckworth L., Barlow M.J., Woods D., Lara J., Siervo M., O’Hara J.P. Dietary nitrate supplementation enhances high-intensity running performance in moderate normobaric hypoxia, independent of aerobic fitness. Nitric Oxide Biol. Chem. 2016;59:63–70. doi: 10.1016/j.niox.2016.08.001. PubMed DOI

Arnold J.T., Oliver S.J., Lewis-Jones T.M., Wylie L.J., Macdonald J.H. Beetroot juice does not enhance altitude running performance in well-trained athletes. Appl. Physiol. Nutr. Metab. 2015;40:590–595. doi: 10.1139/apnm-2014-0470. PubMed DOI

Puype J., Ramaekers M., van Thienen R., Deldicque L., Hespel P. No effect of dietary nitrate supplementation on endurance training in hypoxia. Scand. J. Med. Sci. Sports. 2015;25:234–241. doi: 10.1111/sms.12199. PubMed DOI

Cumpstey A.F., Hennis P.J., Gilbert-Kawai E.T., Fernandez B.O., Grant D., Jenner W., Poudevigne M., Moyses H., Levett D.Z., Cobb A., et al. Effects of dietary nitrate supplementation on microvascular physiology at 4559 m altitude—A randomised controlled trial (Xtreme Alps) Nitric Oxide. 2020;94:27–35. doi: 10.1016/j.niox.2019.10.004. PubMed DOI PMC

Cumpstey A.F., Hennis P.J., Gilbert-Kawai E.T., Fernandez B.O., Poudevigne M., Cobb A., Meale P., Mitchell K., Moyses H., Pöhnl H., et al. Effects of dietary nitrate on respiratory physiology at high altitude—Results from the Xtreme Alps study. Nitric Oxide. 2017;71:57–68. doi: 10.1016/j.niox.2017.10.005. PubMed DOI PMC

Bakker E., Engan H., Patrician A., Schagatay E., Karlsen T., Wisløff U., Gaustad S.E. Acute dietary nitrate supplementation improves arterial endothelial function at high altitude: A double-blinded randomized controlled cross over study. Nitric Oxide. 2015;50:58–64. doi: 10.1016/j.niox.2015.08.006. PubMed DOI

Hultström M. Commentaries on Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J. Appl. Physiol. 2015;119:762–769. doi: 10.1152/japplphysiol.00640.2015. PubMed DOI

Giro d’Italia 2019 | Stage 21 (ITT) | Results. [(accessed on 10 May 2020)]; Available online: https://www.procyclingstats.com/race/giro-d-italia/2019/stage-21.

Tour de France 2018 | Stage 20 (ITT) | Results. [(accessed on 10 May 2020)]; Available online: https://www.procyclingstats.com/race/tour-de-france/2018/stage-20.

Hopkins W.G. Measures of reliability in sports medicine and science. Sports Med. 2000;30:1–15. doi: 10.2165/00007256-200030010-00001. PubMed DOI

Atkinson G., Nevill A.M. Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sports Med. 1998;26:217–238. doi: 10.2165/00007256-199826040-00002. PubMed DOI

Paton C.D., Hopkins W.G. Tests of cycling performance. Sports Med. 2001;31:489–496. doi: 10.2165/00007256-200131070-00004. PubMed DOI

Close G.L., Kasper A.M., Morton J.P. From paper to podium: Quantifying the translational potential of performance nutrition research. Sports Med. 2019;49:25–37. doi: 10.1007/s40279-018-1005-2. PubMed DOI PMC

Piknova B., Park J.W., Swanson K.M., Dey S., Noguchi C.T., Schechter A.N. Skeletal muscle as an endogenous nitrate reservoir. Nitric Oxide. 2015;47:10–16. doi: 10.1016/j.niox.2015.02.145. PubMed DOI PMC

Piknova B., Park J.W., Lam K.K., Schechter A.N. Nitrate as a source of nitrite and nitric oxide during exercise hyperemia in rat skeletal muscle. Nitric Oxide. 2016;55:54–61. doi: 10.1016/j.niox.2016.03.005. PubMed DOI PMC

Gilliard C.N., Lam J.K., Cassel K.S., Park J.W., Schechter A.N., Piknova B. Effect of dietary nitrate levels on nitrate fluxes in rat skeletal muscle and liver. Nitric Oxide. 2018;75:1–7. doi: 10.1016/j.niox.2018.01.010. PubMed DOI PMC

Srihirun S., Park J.W., Teng R., Sawaengdee W., Piknova B., Schechter A.N. Nitrate uptake and metabolism in human skeletal muscle cell cultures. Nitric Oxide. 2020;94:1–8. doi: 10.1016/j.niox.2019.10.005. PubMed DOI PMC

Kapur S., Bédard S., Marcotte B., Côté C.H., Marette A. Expression of nitric oxide synthase in skeletal muscle: A novel role for nitric oxide as a modulator of insulin action. Diabetes. 1997;46:1691–1700. doi: 10.2337/diab.46.11.1691. PubMed DOI

Nyakayiru J., Kouw I.W.K., Cermak N.M., Senden J.M., van Loon L.J.C., Verdijk L.B. Sodium nitrate ingestion increases skeletal muscle nitrate content in humans. J. Appl. Physiol. 2017;123:637–644. doi: 10.1152/japplphysiol.01036.2016. PubMed DOI

McDonagh S.T.J., Wylie L.J., Webster J.M.A., Vanhatalo A., Jones A.M. Influence of dietary nitrate food forms on nitrate metabolism and blood pressure in healthy normotensive adults. Nitric Oxide. 2018;72:66–74. doi: 10.1016/j.niox.2017.12.001. PubMed DOI