Dose-dependent effects of dietary nitrate on the oxygen cost of moderate-intensity exercise: Acute vs. chronic supplementation.
To investigate whether chronic supplementation with a low or moderate dose of dietary nitrate (NO3(-)) reduces submaximal exercise oxygen uptake (V˙O2) and to assess whether or not this is dependent on acute NO3(-) administration prior to exercise.



Following baseline tests, 34 healthy subjects were allocated to receive 3 mmol NO3(-), 6 mmol NO3(-) or placebo. Two hours following the first ingestion, and after 7, 28 and 30 days of supplementation, subjects completed two moderate-intensity step exercise tests. On days 28 and 30, subjects in the NO3(-) groups completed the test 2 h post consumption of a NO3(-) dose (CHR + ACU) and a placebo dose (CHR).



Plasma nitrite concentration ([NO2(-)]) was elevated in a dose-dependent manner at 2 h, 7 days and 28-30 days on the CHR + ACU visit. Compared to pre-treatment baseline, 6 mmol NO3(-) reduced the steady-state V˙O2 during moderate-intensity exercise by 3% at 2 h (P = 0.06), 7 days and at 28-30 days (both P < 0.05) on the CHR + ACU visit, but was unaffected by 3 mmol NO3(-) at all measurement points. On the CHR visit in the 6 mmol group, plasma [NO2(-)] had returned to pre-treatment baseline, but the steady-state V˙O2 remained reduced.



Up to ∼4 weeks supplementation with 6 but not 3 mmol NO3(-) can reduce submaximal exercise V˙O2. A comparable reduction in submaximal exercise V˙O2 following chronic supplementation with 6 mmol NO3(-) can be achieved both with and without the acute ingestion of NO3(-) and associated elevation of plasma [NO2(-)].
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Heavitree, Exeter, EX1 2LU, UK.
Lee J
LJ
Wylie
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Heavitree, Exeter, EX1 2LU, UK.
Joaquin
J
Ortiz de Zevallos
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Heavitree, Exeter, EX1 2LU, UK.
Taro
T
Isidore
Gatorade Sports Science Institute, PepsiCo Global Nutrition R&D, Barrington, IL, USA.
Lara
L
Nyman
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Heavitree, Exeter, EX1 2LU, UK.
Anni
A
Vanhatalo
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Heavitree, Exeter, EX1 2LU, UK.
Stephen J
SJ
Bailey
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Heavitree, Exeter, EX1 2LU, UK. Electronic address: a.m.jones@exeter.ac.uk.
Andrew M
AM
Jones
D000293:Adolescent; D000328:Adult; D019587:Dietary Supplements; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009566:Nitrates / Q000008:administration & dosage* / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000097:blood; D010101:Oxygen Consumption; D064133:Sports Nutritional Physiological Phenomena; D055815:Young Adult
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide
Exercise efficiency; Nitrate supplementation; Nitric oxide; Nitrite; O(2) uptake