Effects of chronic dietary nitrate supplementation on the hemodynamic response to dynamic exercise

Jae Seok Lee, Charles L Stebbins, Eunji Jung, Hosung Nho, Jong Kyung Kim, Myoung Jei Chang, Hyun Min Choi

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

While acute treatment with beetroot juice (BRJ) containing nitrate (NO<sup>‑</sup><inf>3</inf>) can lower systolic blood pressure (SBP), afterload, and myocardial O2 demand during submaximal exercise, effects of chronic supplementation with BRJ (containing a relatively low dose of NO<sup>‑</sup><inf>3</inf>, 400 mg) on cardiac output (CO), SBP, total peripheral resistance (TPR), and the work of the heart in response to dynamic exercise are not known. Thus, in 14 healthy males (22 ± 1 yr), we compared effects of 15 days of both BRJ and nitrate-depleted beetroot juice (NDBRJ) supplementation on plasma concentrations of NOx (N<sup>‑</sup><inf>3</inf>/NO<sup>‑</sup><inf>2</inf>), SBP, diastolic blood pressure (DBP), mean arterial pressure (MAP), CO, TPR, and rate pressure product (RPP) at rest and during progressive cycling exercise. Endothelial function was also assessed via flow-mediated dilation (FMD). BRJ supplementation increased plasma NOx from 83.8 ± 13.8 to 167.6 ± 13.2 µM. Compared with NDBRJ, BRJ reduced SBP, DBP, MAP, and TPR at rest and during exercise (P < 0.05). In addition, RPP was decreased during exercise, while CO was increased, but only at rest and the 30% workload (P < 0.05). BRJ enhanced FMDinduced increases in brachial artery diameter (pre: 12.3 ± 1.6%; post: 17.8 ± 1.9%). We conclude that 1) chronic supplementation with BRJ lowers blood pressure and vascular resistance at rest and during exercise and attenuates RPP during exercise and 2) these effects may be due, in part, to enhanced endothelium-induced vasodilation in contracting skeletal muscle. Findings suggest that BRJ can act as a dietary nutraceutical capable of enhancing O<inf>2</inf> delivery and reducing work of the heart, such that exercise can be performed at a given workload for a longer period of time before the onset of fatigue.

Original languageEnglish (US)
Pages (from-to)R459-R466
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume309
Issue number5
DOIs
StatePublished - Sep 3 2015

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Keywords

  • Afterload
  • Endothelial function
  • Nitrate
  • Nitrite
  • Rate × pressure product
  • Total peripheral resistance

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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