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. 2019 Mar;119(3):723-733.
doi: 10.1007/s00421-018-04063-9. Epub 2019 Jan 8.

An acute dose of inorganic dietary nitrate does not improve high-intensity, intermittent exercise performance in temperate or hot and humid conditions

Kieran Smith  1   2 , David J Muggeridge  3 , Chris Easton  4 , Mark D Ross  5
Affiliations

An acute dose of inorganic dietary nitrate does not improve high-intensity, intermittent exercise performance in temperate or hot and humid conditions

Kieran Smith et al. Eur J Appl Physiol. 2019 Mar.

Abstract

Purpose: Dietary nitrate (NO3-) has repeatedly been shown to improve endurance and intermittent, high-intensity events in temperate conditions. However, the ergogenic effects of dietary NO3- on intermittent exercise performance in hot conditions have yet to be investigated.

Methods: In a randomised, counterbalanced, double-blind crossover study, 12 recreationally trained males ingested a nitrate-rich beetroot juice shot (BRJ) (6.2 mmol NO3-) or a nitrate-depleted placebo (PLA) (< 0.004 mmol NO3-) 3 h prior to an intermittent sprint test (IST) in temperate (22 °C, 35% RH) and hot conditions (30 °C, 70% RH). The cycle ergometer IST consisted of twenty maximal 6 s sprints interspersed by 114 s of active recovery. Work done, power output, heart rate and RPE were measured throughout; tympanic temperature was measured prior to and upon completion.

Results: There were no significant effects of supplement on sprint performance in either temperate or hot, humid conditions (p > 0.05). There was a reduced peak (BRJ: 659 ± 100W vs. PLA: 693 ± 139W; p = 0.056) and mean power (BRJ: 543 ± 29W vs. PLA: 575 ± 38W; p = 0.081) following BRJ compared to PLA in the hot and humid condition, but this was not statistically significant. There was no effect of supplement on total work done irrespective of environmental condition. However, ~ 75% of participants experienced performance decreases following BRJ in the hot and humid environment. No differences were observed between trials for tympanic temperature measured at the conclusion of the exercise trial.

Conclusion: In conclusion, an acute dose of inorganic dietary NO3- does not improve repeated-sprint performance in either temperate, or hot and humid conditions.

Keywords: Beetroot juice; Exercise; Heat; High-intensity; Humidity; Nitrate.

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Conflict of interest statement

The authors report no conflicts of interest.

Figures

Fig. 1
Fig. 1
Mean peak power output (a), mean power production (b) and mean work done (c) produced per sprint during the intermittent sprint test (IST) in temperate conditions after ingesting either nitrate-rich beetroot juice (BRJ) or placebo (PLA). d Illustrates total work done across the twenty 6 s sprints during the IST and e represents fatigue index between trials. Dashed lines represent individual participant response. Data are presented as mean ± SEM
Fig. 2
Fig. 2
Mean peak power output (a), mean power production (b) and mean work done (c) produced per sprint during the intermittent sprint test (IST) in the heat after ingesting either nitrate-rich beetroot juice (BRJ) or placebo (PLA). d Illustrates total work done across the twenty 6 s sprints during the IST and e represents Fatigue Index between trials. Dashed lines represent individual participant response. Data are presented as mean ± SEM
Fig. 3
Fig. 3
Mean power output during the intermittent sprint test (IST) following the nitrate-rich beetroot juice (BRJ; solid) and placebo (PLA; dashed) supplements in temperate (a) and hot and humid (b) conditions. Data are presented as mean ± SEM
Fig. 4
Fig. 4
Mean Work Done per Sprint during the intermittent sprint test (IST) following the nitrate-rich beetroot juice (BRJ; solid) and placebo (PLA; dashed) supplements in temperate (a) and hot and humid (b) conditions. Data are presented as mean ± SEM
Fig. 5
Fig. 5
Mean Power Output during the intermittent sprint test (IST) following the nitrate-rich beetroot juice (BRJ; solid) and placebo (PLA; dashed) supplements in different participants. Example of one of four participants who showed little or no change in performance indices in the IST in temperate (a) and hot, humid conditions (c), and one example of the 8 eight participants who displayed decrements in performance in IST with BRJ supplementation (temperate: b, hot, humid: d)
See this image and copyright information in PMC

References

    1. Almudehki F, Girard O, Grantham J, Racinais S. Hot ambient conditions do not alter intermittent cycling sprint performance. J Sci Med Sport. 2012;15(2):148–152. doi: 10.1016/j.jsams.2011.07.009. - DOI - PubMed
    1. Amano T, Okushima D, Breese BC, Bailey SJ, Koga S, Kondo N. Influence of dietary nitrate supplementation on local sweating and cutaneous vascular responses during exercise in a hot environment. Eur J Appl Physiol. 2018;118(8):1579–1588. doi: 10.1007/s00421-018-3889-9. - DOI - PubMed
    1. Aucouturier J, Boissiere J, Pawlak-Chaouch M, Cuvelier G, Gamelin FX. Effect of dietary nitrate supplementation on tolerance to supramaximal intensity intermittent exercise. Nitric Oxide. 2015;49:16–25. doi: 10.1016/j.niox.2015.05.004. - DOI - PubMed
    1. Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. J Appl Physiol. 2010;109(1):135–148. doi: 10.1152/japplphysiol.00046.2010. - DOI - PubMed
    1. Bishop D, Claudius B. Effects of induced metabolic alkalosis on prolonged intermittent-sprint performance. Med Sci Sports Exerc. 2005;37(5):759–767. doi: 10.1249/01.MSS.0000161803.44656.3C. - DOI - PubMed

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