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Acute dietary nitrate supplementation and exercise performance in COPD: a double-blind, placebo-controlled, randomised controlled pilot study

Acute dietary nitrate supplementation and exercise performance in COPD: a double-blind, placebo-controlled, randomised controlled pilot study
Acute dietary nitrate supplementation and exercise performance in COPD: a double-blind, placebo-controlled, randomised controlled pilot study
Background: Dietary nitrate supplementation can enhance exercise performance in healthy people, but it is not clear if it is beneficial in COPD. We investigated the hypotheses that acute nitrate dosing would improve exercise performance and reduce the oxygen cost of submaximal exercise in people with COPD.

Methods: We performed a double-blind, placebo-controlled, cross-over single dose study. Subjects were randomised to consume either nitrate-rich beetroot juice (containing 12.9mmoles nitrate) or placebo (nitrate-depleted beetroot juice) 3 hours prior to endurance cycle ergometry, performed at 70% of maximal workload assessed by a prior incremental exercise test. After a minimum washout period of 7 days the protocol was repeated with the crossover beverage.

Results: 21 subjects successfully completed the study (age 68±7years; BMI 25.2±5.5kg/m2; FEV1 percentage predicted 50.1±21.6%; peak VO2 18.0±5.9ml/min/kg). Resting diastolic blood pressure fell significantly with nitrate supplementation compared to placebo (-7±8mmHg nitrate vs. -1±8mmHg placebo; p = 0.008). Median endurance time did not differ significantly; nitrate 5.65 (3.90–10.40) minutes vs. placebo 6.40 (4.01–9.67) minutes (p = 0.50). However, isotime oxygen consumption (VO2) was lower following nitrate supplementation (16.6±6.0ml/min/kg nitrate vs. 17.2±6.0ml/min/kg placebo; p = 0.043), and consequently nitrate supplementation caused a significant lowering of the amplitude of the VO2-percentage isotime curve.

Conclusions: Acute administration of oral nitrate did not enhance endurance exercise performance; however the observation that beetroot juice caused reduced oxygen consumption at isotime suggests that further investigation of this treatment approach is warranted, perhaps targeting a more hypoxic phenotype.

Trial Registration: ISRCTN Registry ISRCTN66099139
1932-6203
1-18
Curtis, Katrina J.
e3edc386-2a76-47b4-925f-10c1299e7040
O'Brien, Katie A.
548aadd1-580b-41e7-bc91-cecd0f8997fe
Tanner, Rebecca J.
36a008fb-5a7c-4314-a5c5-927b0483186c
Polkey, Juliet I.
c267ea34-d7f0-4385-b7f5-6545478f0024
Minnion, Magdalena
ab23b32b-9f8e-4876-aaf5-99cb6a725a2f
Feelisch, Martin
8c1b9965-8614-4e85-b2c6-458a2e17eafd
Polkey, Michael I.
4f841dc9-9b94-4021-bbfc-64092cddc7b6
Edwards, Lindsay M.
b340a399-eac0-40b8-ba26-b1f618f6687b
Hopkinson, Nicholas S.
91e9a2af-8ab3-4671-b766-761e82bd5310
Curtis, Katrina J.
e3edc386-2a76-47b4-925f-10c1299e7040
O'Brien, Katie A.
548aadd1-580b-41e7-bc91-cecd0f8997fe
Tanner, Rebecca J.
36a008fb-5a7c-4314-a5c5-927b0483186c
Polkey, Juliet I.
c267ea34-d7f0-4385-b7f5-6545478f0024
Minnion, Magdalena
ab23b32b-9f8e-4876-aaf5-99cb6a725a2f
Feelisch, Martin
8c1b9965-8614-4e85-b2c6-458a2e17eafd
Polkey, Michael I.
4f841dc9-9b94-4021-bbfc-64092cddc7b6
Edwards, Lindsay M.
b340a399-eac0-40b8-ba26-b1f618f6687b
Hopkinson, Nicholas S.
91e9a2af-8ab3-4671-b766-761e82bd5310

Curtis, Katrina J., O'Brien, Katie A., Tanner, Rebecca J., Polkey, Juliet I., Minnion, Magdalena, Feelisch, Martin, Polkey, Michael I., Edwards, Lindsay M. and Hopkinson, Nicholas S. (2015) Acute dietary nitrate supplementation and exercise performance in COPD: a double-blind, placebo-controlled, randomised controlled pilot study. PLoS ONE, 10 (12), 1-18. (doi:10.1371/journal.pone.0144504). (PMID:26698120)

Record type: Article

Abstract

Background: Dietary nitrate supplementation can enhance exercise performance in healthy people, but it is not clear if it is beneficial in COPD. We investigated the hypotheses that acute nitrate dosing would improve exercise performance and reduce the oxygen cost of submaximal exercise in people with COPD.

Methods: We performed a double-blind, placebo-controlled, cross-over single dose study. Subjects were randomised to consume either nitrate-rich beetroot juice (containing 12.9mmoles nitrate) or placebo (nitrate-depleted beetroot juice) 3 hours prior to endurance cycle ergometry, performed at 70% of maximal workload assessed by a prior incremental exercise test. After a minimum washout period of 7 days the protocol was repeated with the crossover beverage.

Results: 21 subjects successfully completed the study (age 68±7years; BMI 25.2±5.5kg/m2; FEV1 percentage predicted 50.1±21.6%; peak VO2 18.0±5.9ml/min/kg). Resting diastolic blood pressure fell significantly with nitrate supplementation compared to placebo (-7±8mmHg nitrate vs. -1±8mmHg placebo; p = 0.008). Median endurance time did not differ significantly; nitrate 5.65 (3.90–10.40) minutes vs. placebo 6.40 (4.01–9.67) minutes (p = 0.50). However, isotime oxygen consumption (VO2) was lower following nitrate supplementation (16.6±6.0ml/min/kg nitrate vs. 17.2±6.0ml/min/kg placebo; p = 0.043), and consequently nitrate supplementation caused a significant lowering of the amplitude of the VO2-percentage isotime curve.

Conclusions: Acute administration of oral nitrate did not enhance endurance exercise performance; however the observation that beetroot juice caused reduced oxygen consumption at isotime suggests that further investigation of this treatment approach is warranted, perhaps targeting a more hypoxic phenotype.

Trial Registration: ISRCTN Registry ISRCTN66099139

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Accepted/In Press date: 15 November 2015
Published date: 23 December 2015
Organisations: Clinical & Experimental Sciences

Identifiers

Local EPrints ID: 390055
URI: https://eprints.soton.ac.uk/id/eprint/390055
ISSN: 1932-6203
PURE UUID: 8f86dd25-a811-461d-90ed-d246cf3a4341
ORCID for Martin Feelisch: ORCID iD orcid.org/0000-0003-2320-1158

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Date deposited: 17 Mar 2016 14:41
Last modified: 06 Jun 2018 12:29

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Contributors

Author: Katrina J. Curtis
Author: Katie A. O'Brien
Author: Rebecca J. Tanner
Author: Juliet I. Polkey
Author: Magdalena Minnion
Author: Martin Feelisch ORCID iD
Author: Michael I. Polkey
Author: Lindsay M. Edwards
Author: Nicholas S. Hopkinson

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