Faculty Collaboration Database

Dietary nitrate does not acutely enhance skeletal muscle blood flow and vasodilation in the lower limbs of older adults during single-limb exercise. Eur J Appl Physiol 2020 Jun;120(6):1357-1369

Date

04/19/2020

Pubmed ID

32303829

DOI

10.1007/s00421-020-04368-8

Scopus ID

2-s2.0-85083592813 (requires institutional sign-in at Scopus site)   6 Citations

Abstract

PURPOSE: Blood flow (BF) and vasodilator responses to knee-extension exercise are attenuated in older adults across an exercise transient (onset, kinetics, and steady-state), and reduced nitric oxide bioavailability (NO) has been hypothesized to be a primary mechanism contributing to this attenuation. We tested the hypothesis acute dietary nitrate (NO₃^-) supplementation (~ 4.03 mmol NO₃^- and 0.29 mmol NO₂^-) would improve leg vasodilator responses across an exercise transient during lower limb exercise in older adults.

METHODS: Older (n = 10) untrained adults performed single and rhythmic knee-extension contractions at 20% and 40% work-rate maximum (WR_max) prior to and 2-h after consuming a NO₃^- or placebo beverage in a double-blind, randomized fashion. Femoral artery BF was measured by Doppler ultrasound. Vascular conductance was calculated using BF and mean arterial pressure.

RESULTS: Acute ingestion of dietary NO₃^- enhanced plasma [NO₃^-] and [NO₂^-] (P < 0.05). Neither dietary NO₃^- or placebo enhanced vasodilator responses at the onset of exercise or during steady state at 20% and 40% WR_max (P > 0.05). Leg vasodilator kinetics during rhythmic exercise remained unchanged following NO₃^- and placebo ingestion (P > 0.05).

CONCLUSIONS: The key findings of this study are that despite increasing plasma [NO₃^-] and [NO₂^-]_, acute dietary NO₃^- intake had no effect on (1) rapid hyperaemic or vasodilator responses at the onset of exercise; (2) hyperaemic and vasodilator responses during steady-state submaximal exercise; or (3) kinetics of vasodilation preceding steady-state responses. Collectively, these findings suggest that low dose dietary NO₃^- supplementation does not improve hyperaemic and vasodilator responses across an exercise transient in older adults.

Author List

Hughes WE, Kruse NT, Ueda K, Feider AJ, Hanada S, Bock JM, Casey DP

Author

William E. Hughes Postdoctoral Fellow in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Aged
Blood Pressure
Composite Resins
Double-Blind Method
Exercise
Female
Femoral Artery
Glass Ionomer Cements
Heart Rate
Hemodynamics
Humans
Lower Extremity
Male
Muscle Contraction
Muscle, Skeletal
Nitrates
Regional Blood Flow
Ultrasonography, Doppler
Vasodilation