Anthony I Shepherd1, Daryl P Wilkerson2, Lee Dobson3, James Kelly2, Paul G Winyard4, Andrew M Jones2, Nigel Benjamin5, Angela C Shore4, Mark Gilchrist6. 1. College of Life and Environmental Sciences, Sport and Health Sciences, University of Exeter, Devon, UK; NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, University of Exeter Medical School, Exeter, Devon, UK. 2. College of Life and Environmental Sciences, Sport and Health Sciences, University of Exeter, Devon, UK. 3. Heart and Lung Unit, Torbay Hospital, Torquay, Devon, UK. 4. NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, University of Exeter Medical School, Exeter, Devon, UK. 5. NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, University of Exeter Medical School, Exeter, Devon, UK; Heart and Lung Unit, Torbay Hospital, Torquay, Devon, UK. 6. NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, University of Exeter Medical School, Exeter, Devon, UK. Electronic address: m.gilchrist@exeter.ac.uk.
Abstract
BACKGROUND:Chronic obstructive pulmonary disease (COPD) results in exercise intolerance. Dietary nitrate supplementation has been shown to lower blood pressure (BP), reduce the oxygen cost of exercise, and enhance exercise tolerance in healthy volunteers. This study assessed the effects of dietary nitrate on the oxygen cost of cycling, walking performance and BP in individuals with mild-moderate COPD. METHODS:Thirteen patients with mild-moderate COPD were recruited. Participants consumed 70 ml of either nitrate-rich (6.77 mmol nitrate; beetroot juice) or nitrate-depleted beetroot juice (0.002 mmol nitrate; placebo) twice a day for 2.5 days, with the final supplement ~3 hours before testing. BP was measured before completing two bouts of moderate-intensity cycling, where pulmonary gas exchange was measured throughout. The six-minute walk test (6 MWT) was completed 30 minutes subsequent to the second cycling bout. RESULTS:Plasma nitrate concentration was significantly elevated following beetroot juice vs. placebo (placebo; 48 ± 86 vs. beetroot juice; 215 ± 84 µM, P = 0.002). No significant differences were observed between placebo vs. beetroot juice for oxygen cost of exercise (933 ± 323 vs. 939 ± 302 ml: min(-1); P = 0.88), distance covered in the 6 MWT (456 ± 86 vs. 449 ± 79 m; P = 0.37), systolic BP (123 ± 14 vs. 123 ± 14 mmHg; P = 0.91), or diastolic BP (77 ± 9 vs. 79 ± 9 mmHg; P = 0.27). CONCLUSION: Despite a large rise in plasma nitrate concentration, two days of nitrate supplementation did not reduce the oxygen cost of moderate intensity cycling, increase distance covered in the 6 MWT, or lower BP.
RCT Entities:
BACKGROUND:Chronic obstructive pulmonary disease (COPD) results in exercise intolerance. Dietary nitrate supplementation has been shown to lower blood pressure (BP), reduce the oxygen cost of exercise, and enhance exercise tolerance in healthy volunteers. This study assessed the effects of dietary nitrate on the oxygen cost of cycling, walking performance and BP in individuals with mild-moderate COPD. METHODS: Thirteen patients with mild-moderate COPD were recruited. Participants consumed 70 ml of either nitrate-rich (6.77 mmol nitrate; beetroot juice) or nitrate-depleted beetroot juice (0.002 mmol nitrate; placebo) twice a day for 2.5 days, with the final supplement ~3 hours before testing. BP was measured before completing two bouts of moderate-intensity cycling, where pulmonary gas exchange was measured throughout. The six-minute walk test (6 MWT) was completed 30 minutes subsequent to the second cycling bout. RESULTS: Plasma nitrate concentration was significantly elevated following beetroot juice vs. placebo (placebo; 48 ± 86 vs. beetroot juice; 215 ± 84 µM, P = 0.002). No significant differences were observed between placebo vs. beetroot juice for oxygen cost of exercise (933 ± 323 vs. 939 ± 302 ml: min(-1); P = 0.88), distance covered in the 6 MWT (456 ± 86 vs. 449 ± 79 m; P = 0.37), systolic BP (123 ± 14 vs. 123 ± 14 mmHg; P = 0.91), or diastolic BP (77 ± 9 vs. 79 ± 9 mmHg; P = 0.27). CONCLUSION: Despite a large rise in plasma nitrate concentration, two days of nitrate supplementation did not reduce the oxygen cost of moderate intensity cycling, increase distance covered in the 6 MWT, or lower BP.
Authors: Andrew R Coggan; Joshua L Leibowitz; Catherine Anderson Spearie; Ana Kadkhodayan; Deepak P Thomas; Sujata Ramamurthy; Kiran Mahmood; Soo Park; Suzanne Waller; Marsha Farmer; Linda R Peterson Journal: Circ Heart Fail Date: 2015-07-15 Impact factor: 8.790
Authors: Anthony I Shepherd; Joseph T Costello; Stephen J Bailey; Nicolette Bishop; Alex J Wadley; Steven Young-Min; Mark Gilchrist; Harry Mayes; Danny White; Paul Gorczynski; Zoe L Saynor; Heather Massey; Clare M Eglin Journal: J Appl Physiol (1985) Date: 2019-07-25
Authors: Anthony I Shepherd; Daryl P Wilkerson; Jon Fulford; Paul G Winyard; Nigel Benjamin; Angela C Shore; Mark Gilchrist Journal: Am J Physiol Gastrointest Liver Physiol Date: 2016-07-14 Impact factor: 4.052
Authors: Charlotte Elizabeth Mills; Jibran Khatri; Perry Maskell; Chimed Odongerel; Andrew James Webb Journal: Br J Clin Pharmacol Date: 2016-05-06 Impact factor: 4.335
Authors: Paul Leong; Jane E Basham; Theresa Yong; Adrian Chazan; Paul Finlay; Sara Barnes; Phillip G Bardin; Donald Campbell Journal: BMC Pulm Med Date: 2015-05-02 Impact factor: 3.317
Authors: Katrina J Curtis; Katie A O'Brien; Rebecca J Tanner; Juliet I Polkey; Magdalena Minnion; Martin Feelisch; Michael I Polkey; Lindsay M Edwards; Nicholas S Hopkinson Journal: PLoS One Date: 2015-12-23 Impact factor: 3.240