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Appl Physiol Nutr Metab. 2015 Feb;40(2):122-8. doi: 10.1139/apnm-2014-0228. Epub 2014 Oct 15.

Acute dietary nitrate supplementation does not augment submaximal forearm exercise hyperemia in healthy young men.

Author information

1
a Intercollege Graduate Degree Program in Physiology, The Pennsylvania State University, University Park, PA 16802, USA.

Abstract

Despite the popularity of dietary nitrate supplementation and the growing evidence base of its potential ergogenic and vascular health benefits, there is no direct information about its effects on exercising limb blood flow in humans. We hypothesized that acute dietary nitrate supplementation from beetroot juice would augment the increases in forearm blood flow, as well as the progressive dilation of the brachial artery, during graded handgrip exercise in healthy young men. In a randomized, double-blind, placebo-controlled crossover study, 12 young (22 ± 2 years) healthy men consumed a beetroot juice (140 mL Beet-It Sport, James White Juice Company) that provided 12.9 mmol (0.8 g) of nitrate or placebo (nitrate-depleted Beet-It Sport) on 2 study visits. At 3 h postconsumption, brachial artery diameter, flow, and blood velocity were measured (Doppler ultrasound) at rest and during 6 exercise intensities. Nitrate supplementation raised plasma nitrate (19.5-fold) and nitrite (1.6-fold) concentrations, and lowered resting arterial pulse wave velocity (PWV) versus placebo (all p < 0.05), indicating absorption, conversion, and a biological effect of this supplement. The supplement-associated lowering of PWV was also negatively correlated with plasma nitrite (r = -0.72, p = 0.0127). Despite these systemic effects, nitrate supplementation had no effect on brachial artery diameter, flow, or shear rates at rest (all p ≥ 0.28) or during any exercise workload (all p ≥ 0.18). These findings suggest that acute dietary nitrate supplementation favorably modifies arterial PWV, but does not augment blood flow or brachial artery vasodilation during nonfatiguing forearm exercise in healthy young men.

KEYWORDS:

fonction vasculaire; inorganic nitrate; nitrate inorganique; pulse wave velocity; vascular function; vélocité de l’onde pulsatile

PMID:
25536008
PMCID:
PMC4314377
DOI:
10.1139/apnm-2014-0228
[Indexed for MEDLINE]
Free PMC Article

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