Effects of nitrate supplementation in trained and untrained muscle are modest with initial high plasma nitrite levels. (16th March 2017)

• Record Type: Journal Article
• Authors: Christensen, P. M.; Petersen, N. K.; Friis, S. N.; Weitzberg, E.; Nybo, L.
• Is Part Of: Scandinavian journal of medicine & science in sports. Volume 27:Number 12(2017)
• Page Start: 1616
• Page End: 1626
• Publication Date: 2017-03-16
• Subjects: blood pressure -- cycling economy -- NO bioavailability -- VO2‐max; Sports medicine -- Periodicals; Sports -- Physiological aspects -- Periodicals; Sports -- Periodicals; 617.1027
• DOI: 10.1111/sms.12848
• Languages: English
• ISSNs: 0905-7188

Abstract

Abstract : Nitrate ( NO 3 − ) supplementation resulting in higher plasma nitrite ( NO 2 − ) is reported to lower resting mean arterial blood pressure (MAP) and oxygen uptake (VO2 ) during submaximal exercise in non‐athletic populations, whereas effects in general are absent in endurance‐trained individuals. To test whether physiologic effects of NO 3 − supplementation depend on local muscular training status or cardiovascular fitness, male endurance‐trained cyclists (CYC, n=9, VO2 ‐max: 64±3 mL/min/kg; mean±SD) and recreational active subjects serving as a control group (CON, n=8, 46±3 mL/min/kg), acutely consumed nitrate‐rich beetroot juice ([ NO 3 − ] ~9 mmol) (NIT) or placebo (PLA) with assessment of resting MAP and energy expenditure during moderate intensity (~50% VO2 ‐max) and incremental leg cycling (LEG‐ex) and arm‐cranking exercise (ARM‐ex). NIT increased ( P <.001) resting plasma NO 3 − by ~1200% relative to PLA. Plasma NO 2 − increased ~25% ( P <.01) with a significant change only in CYC. LEG‐ex VO2 (~2.60 L/min), ARM‐ex VO2 (~1.14 L/min), and resting MAP (~87 mm Hg) remained unchanged for CYC, and similarly for CON, no changes were observed for LEG‐ex VO2 (~2.03 L/min), ARM‐ex VO2 (~1.06 L/min), or resting MAP (~85 mm Hg). VO2 ‐max was not affected by supplementation, but incremental test peak power was higher ( P <.05) in LEG‐ex for CYC in NIT relative to PLA (418±47 vs 407±46 W). In both CYC and CON, high initial baseline values and small increases in plasma NO 2 − after NIT may have lowered the effect of the intervention implying that muscular and cardiovascular training status is likely not the only factors that influence the physiologic effects of NO 3 − supplementation.