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Eur J Appl Physiol. 2018 May 15. doi: 10.1007/s00421-018-3889-9. [Epub ahead of print]

Influence of dietary nitrate supplementation on local sweating and cutaneous vascular responses during exercise in a hot environment.

Author information

1
Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-ku, Kobe, 657-8501, Japan.
2
Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan.
3
Applied Physiology Laboratory, Kobe Design University, Kobe, Japan.
4
School of Biomedical and Healthcare Sciences, Plymouth University, Plymouth, UK.
5
School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
6
Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-ku, Kobe, 657-8501, Japan. kondo@kobe-u.ac.jp.

Abstract

PURPOSE:

We investigated the influence of inorganic nitrate ([Formula: see text]) supplementation on local sweating and cutaneous vascular responses during exercise in hot conditions.

METHOD:

Eight healthy, young subjects were assigned in a randomized, double-blind, crossover design to receive [Formula: see text]-rich beetroot (BR) juice (140 mL/day, containing ~ 8 mmol of [Formula: see text]) and [Formula: see text]-depleted placebo (PL) juice (140 mL/day, containing ~ 0.003 mmol of [Formula: see text]) for 3 days. On day 3 of supplementation, subjects cycled at an intensity corresponding to 55% of [Formula: see text]O2max for 30 min in hot conditions (30 °C, 50% relative humidity). Chest and forearm sweat rate (SR) and skin blood flow (SkBF), were measured continuously. Cutaneous vascular conductance (CVC) was calculated by SkBF/mean arterial pressure (MAP).

RESULTS:

Prior to exercise, plasma [Formula: see text] (21 ± 6 and 581 ± 161 µM) and nitrite ([Formula: see text], 87 ± 28 and 336 ± 156 nM) concentrations were higher after BR compared to PL supplementation (P ≤ 0.011, n = 6). Oesophageal, mean skin, and mean body temperatures during exercise were not different between conditions. In addition, BR supplementation did not affect SR, SkBF, and CVC during exercise. A lower MAP was found after 30 min of exercise following BR supplementation (112 ± 6 and 103 ± 6 mmHg for PL and BR, respectively, P = 0.021).

CONCLUSION:

These results suggest that inorganic [Formula: see text] supplementation, which increases the potential for O2-independent NO production, does not affect local sweating and cutaneous vascular responses, but attenuates blood pressure in young healthy subjects exercising in a hot environment.

KEYWORDS:

Heat loss response; Nitric oxide synthesis; Sweat glands; Thermoregulation

PMID:
29766294
DOI:
10.1007/s00421-018-3889-9

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