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

Kieran Smith, David J. Muggeridge, Chris Easton, Mark D. Ross

Research output: Contribution to journalArticle

Abstract

Purpose
Exercise in hot and humid conditions augments a rise in core body temperature, leading to premature fatigue and performance impairments. Dietary nitrate (NO3-) has repeatedly been shown to improve self-paced endurance and intermittent, high-intensity events in ambient conditions. However, the ergogenic effects of dietary NO3- on intermittent exercise performance in hot conditions has yet to be investigated.

Methods
In a randomised, counterbalanced, double-blind crossover study, twelve trained males ingested a nitrate-rich beetroot juice shot (BRJ) (8.2 mmol NO3-) or a nitrate-depleted placebo (PLA) (<0.004mmol NO3-) 3h prior to an intermittent sprint test (IST) in ambient (22°C, 35% RH) and hot conditions (30°C, 70% RH). The cycle ergometer IST consisted of twenty maximal 6s sprints interspersed by 114s 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 trial x time effects were found on sprint performance in either ambient or hot, humid conditions (p>0.05). There was a reduced peak (BRJ: 659±100W vs. PLA: 693±139W; p=0.056; d=0.28) and mean power (BRJ: 543 ± 29W vs PLA: 575 ± 38W; p=0.081; d=0.27) 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 (ambient: p = 0.447, d = 0.07, hot and humid: p = 0.101, d = 0.28) 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 (BRJ: 37.3 ± 0.7°C vs PLA: 37.3 ± 0.6°C; p=0.93).

Conclusion
In conclusion, an acute dose of inorganic dietary NO3- does not improve repeated sprint performance in either ambient, or hot and humid conditions.
LanguageEnglish
Number of pages11
JournalEuropean Journal of Applied Physiology
Early online date8 Jan 2019
DOIs
StateE-pub ahead of print - 8 Jan 2019

Fingerprint

Nitrates
Placebos
Performance-Enhancing Substances
Temperature
Body Temperature
Double-Blind Method
Cross-Over Studies
Fatigue
Heart Rate
High-Intensity Interval Training

Keywords

  • Nitrate
  • Exercise
  • Heat
  • High-intensity
  • Beetroot juice
  • Humidity

Cite this

@article{cbbd7a81493343db9db8a715e457a0e6,
title = "An acute dose of inorganic dietary nitrate does not improve high-intensity, intermittent exercise performance in temperate or hot and humid conditions",
abstract = "PurposeExercise in hot and humid conditions augments a rise in core body temperature, leading to premature fatigue and performance impairments. Dietary nitrate (NO3-) has repeatedly been shown to improve self-paced endurance and intermittent, high-intensity events in ambient conditions. However, the ergogenic effects of dietary NO3- on intermittent exercise performance in hot conditions has yet to be investigated. MethodsIn a randomised, counterbalanced, double-blind crossover study, twelve trained males ingested a nitrate-rich beetroot juice shot (BRJ) (8.2 mmol NO3-) or a nitrate-depleted placebo (PLA) (<0.004mmol NO3-) 3h prior to an intermittent sprint test (IST) in ambient (22°C, 35\{%} RH) and hot conditions (30°C, 70\{%} RH). The cycle ergometer IST consisted of twenty maximal 6s sprints interspersed by 114s of active recovery. Work done, power output, heart rate and RPE were measured throughout; tympanic temperature was measured prior to and upon completion. ResultsThere were no significant trial x time effects were found on sprint performance in either ambient or hot, humid conditions (p>0.05). There was a reduced peak (BRJ: 659±100W vs. PLA: 693±139W; p=0.056; d=0.28) and mean power (BRJ: 543 ± 29W vs PLA: 575 ± 38W; p=0.081; d=0.27) 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 (ambient: p = 0.447, d = 0.07, hot and humid: p = 0.101, d = 0.28) 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 (BRJ: 37.3 ± 0.7°C vs PLA: 37.3 ± 0.6°C; p=0.93). ConclusionIn conclusion, an acute dose of inorganic dietary NO3- does not improve repeated sprint performance in either ambient, or hot and humid conditions.",
keywords = "Nitrate, Exercise, Heat, High-intensity, Beetroot juice, Humidity",
author = "Kieran Smith and Muggeridge, {David J.} and Chris Easton and Ross, {Mark D.}",
year = "2019",
month = "1",
day = "8",
doi = "10.1007/s00421-018-04063-9",
language = "English",
journal = "European Journal of Applied Physiology",
issn = "1439-6319",
publisher = "Springer-Verlag",

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TY - JOUR

T1 - An acute dose of inorganic dietary nitrate does not improve high-intensity, intermittent exercise performance in temperate or hot and humid conditions

AU - Smith,Kieran

AU - Muggeridge,David J.

AU - Easton,Chris

AU - Ross,Mark D.

PY - 2019/1/8

Y1 - 2019/1/8

N2 - PurposeExercise in hot and humid conditions augments a rise in core body temperature, leading to premature fatigue and performance impairments. Dietary nitrate (NO3-) has repeatedly been shown to improve self-paced endurance and intermittent, high-intensity events in ambient conditions. However, the ergogenic effects of dietary NO3- on intermittent exercise performance in hot conditions has yet to be investigated. MethodsIn a randomised, counterbalanced, double-blind crossover study, twelve trained males ingested a nitrate-rich beetroot juice shot (BRJ) (8.2 mmol NO3-) or a nitrate-depleted placebo (PLA) (<0.004mmol NO3-) 3h prior to an intermittent sprint test (IST) in ambient (22°C, 35% RH) and hot conditions (30°C, 70% RH). The cycle ergometer IST consisted of twenty maximal 6s sprints interspersed by 114s of active recovery. Work done, power output, heart rate and RPE were measured throughout; tympanic temperature was measured prior to and upon completion. ResultsThere were no significant trial x time effects were found on sprint performance in either ambient or hot, humid conditions (p>0.05). There was a reduced peak (BRJ: 659±100W vs. PLA: 693±139W; p=0.056; d=0.28) and mean power (BRJ: 543 ± 29W vs PLA: 575 ± 38W; p=0.081; d=0.27) 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 (ambient: p = 0.447, d = 0.07, hot and humid: p = 0.101, d = 0.28) 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 (BRJ: 37.3 ± 0.7°C vs PLA: 37.3 ± 0.6°C; p=0.93). ConclusionIn conclusion, an acute dose of inorganic dietary NO3- does not improve repeated sprint performance in either ambient, or hot and humid conditions.

AB - PurposeExercise in hot and humid conditions augments a rise in core body temperature, leading to premature fatigue and performance impairments. Dietary nitrate (NO3-) has repeatedly been shown to improve self-paced endurance and intermittent, high-intensity events in ambient conditions. However, the ergogenic effects of dietary NO3- on intermittent exercise performance in hot conditions has yet to be investigated. MethodsIn a randomised, counterbalanced, double-blind crossover study, twelve trained males ingested a nitrate-rich beetroot juice shot (BRJ) (8.2 mmol NO3-) or a nitrate-depleted placebo (PLA) (<0.004mmol NO3-) 3h prior to an intermittent sprint test (IST) in ambient (22°C, 35% RH) and hot conditions (30°C, 70% RH). The cycle ergometer IST consisted of twenty maximal 6s sprints interspersed by 114s of active recovery. Work done, power output, heart rate and RPE were measured throughout; tympanic temperature was measured prior to and upon completion. ResultsThere were no significant trial x time effects were found on sprint performance in either ambient or hot, humid conditions (p>0.05). There was a reduced peak (BRJ: 659±100W vs. PLA: 693±139W; p=0.056; d=0.28) and mean power (BRJ: 543 ± 29W vs PLA: 575 ± 38W; p=0.081; d=0.27) 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 (ambient: p = 0.447, d = 0.07, hot and humid: p = 0.101, d = 0.28) 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 (BRJ: 37.3 ± 0.7°C vs PLA: 37.3 ± 0.6°C; p=0.93). ConclusionIn conclusion, an acute dose of inorganic dietary NO3- does not improve repeated sprint performance in either ambient, or hot and humid conditions.

KW - Nitrate

KW - Exercise

KW - Heat

KW - High-intensity

KW - Beetroot juice

KW - Humidity

U2 - 10.1007/s00421-018-04063-9

DO - 10.1007/s00421-018-04063-9

M3 - Article

JO - European Journal of Applied Physiology

T2 - European Journal of Applied Physiology

JF - European Journal of Applied Physiology

SN - 1439-6319

ER -