No thermoregulatory or ergogenic effect of dietary nitrate among physically inactive males, exercising above gas exchange threshold in hot and dry conditions

Fowler, Rebecca, Jeffries, Owen, Tallent, Jamie, Theis, Nicola ORCID: 0000-0002-0775-1355, Heffernan, Shane M., McNarry, Melitta A., Kilduff, Liam and Waldron, Mark (2020) No thermoregulatory or ergogenic effect of dietary nitrate among physically inactive males, exercising above gas exchange threshold in hot and dry conditions. European Journal of Sport Science. ISSN 1746-1391 (In Press)

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Abstract

The aim of this study was to determine the effect of five days dietary nitrate (NO3-) consumption on exercise tolerance and thermoregulation during cycling in hot, dry conditions. In a double-blind, randomised crossover design, 11 healthy males participated in an exercise tolerance test (Tlim) in the heat (35°C, 28% relative humidity), cycling above the thermoneutral gas exchange threshold, after five days of dietary supplementation, with either NO3--rich beetroot juice (BR; ~ 9.2 mmol NO3-) or placebo (PLA). Changes in plasma [NO3-] and nitrite [NO2-], core and mean skin temperatures, mean local and whole-body sweat rates, heart rate, perceptual ratings and pulmonary gas exchange were measured during exercise, alongside calorimetric estimations of thermal balance. Mean arterial pressures (MAP) were recorded pre-Tlim. There were no differences in Tlim between conditions (BR = 22.8 ± 8.1 min; Placebo = 20.7 ± 7.9 min) (P = 0.184), despite increases in plasma [NO3-] and [NO2-] (P < 0.001) and a 3.8% reduction in resting MAP (P = 0.004) in the BR condition. There were no other differences in thermoregulatory, cardio-metabolic, perceptual or calorimetric responses to the Tlim between conditions (P > 0.05). Dietary NO3- supplementation had no effect on exercise tolerance or thermoregulation in hot, dry conditions, despite reductions in resting MAP and increases in plasma [NO3-] and [NO2-]. Healthy, yet physically inactive individuals with no known impairments in vasodilatory and sudomotor function do not appear to require BR for ergogenic or thermolytic effects during exercise in the heat.

Item Type: Article
Article Type: Article
Additional Information: This is an Accepted Manuscript of an article published by Taylor & Francis in European Journal of Sport Science on 4th of March 2020, available online: https://www.tandfonline.com/doi/full/10.1080/17461391.2020.1739144
Uncontrolled Keywords: Beetroot; Hot; Sweating; Cooling; Ergogenic aids
Subjects: Q Science > QP Physiology
Q Science > QP Physiology > QP301.H75 Physiology. Sport
Divisions: Schools and Research Institutes > School of Sport and Exercise
Research Priority Areas: Sport, Exercise, Health & Wellbeing
Depositing User: Rhiannon Goodland
Date Deposited: 17 Mar 2020 11:28
Last Modified: 17 Mar 2020 11:30
URI: http://eprints.glos.ac.uk/id/eprint/8233

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