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Title: The effect of dietary nitrate supplementation on the spatial heterogeneity of quadriceps deoxygenation during heavy-intensity cycling
Authors: Breese, Brynmor C.
Poole, David C.
Okushima, Dai
Bailey, Stephen J.
Jones, Andrew M.
Kondo, N.
Amano, Tatsuro
Koga, Shunsaku
Keywords: Time resolved near-infrared spectroscopy
Nitrate supplementation
Heterogeneity
Oxygen delivery
Oxygen utilization
Issue Date: 2017
Publisher: Wiley on behalf of The Physiological Society and the American Physiological Society © The authors
Citation: The effect of dietary nitrate supplementation on the spatial heterogeneity of quadriceps deoxygenation during heavy-intensity cycling. Physiological Reports, 5 (14), e13340.
Abstract: This study investigated the influence of dietary inorganic nitrate (NO3-) supplementation on pulmonary O2 uptake ( o2) and muscle deoxyhemoglobin/myoglobin (i.e. deoxy[Hb+Mb]) kinetics during submaximal cycling exercise. In a randomized, placebo-controlled, cross-over study, eight healthy and physically active male subjects completed multiple step cycle tests at a work rate equivalent to 50% of the difference between the gas exchange threshold and peak o2 over separate 4-day supplementation periods with NO3--rich (BR; providing 8.4 mmol NO3-∙day-1) and NO3--depleted (placebo; PLA) beetroot juice. Pulmonary o2 was measured breath-by-breath and time-resolved near-infrared spectroscopy was utilized to quantify absolute deoxy[Hb+Mb] and total[Hb+Mb] within the rectus femoris, vastus lateralis, and vastus medialis. There were no significant differences (P > 0.05) in the primary deoxy[Hb+Mb] mean response time or amplitude between the PLA and BR trials at each muscle site. BR significantly increased the mean (three-site) end-exercise deoxy[Hb+Mb] (PLA: 91 ± 9 vs. BR: 95 ± 12 µM, P < 0.05), with a tendency to increase the mean (three-site) area under the curve for total(Hb+Mb) responses (PLA: 3650 ± 1188 vs. BR: 4467 ± 1315 µM·s-1, P = 0.08). The o2 slow component reduction after BR supplementation (PLA: 0.27 ± 0.07 vs. BR: 0.23 ± 0.08 L·min-1, P = 0.07) correlated inversely with the mean increases in deoxy[Hb+Mb] and total[Hb+Mb] across the three muscle regions (r2 = 0.62 and 0.66, P < 0.05). Dietary NO3- supplementation increased O2 diffusive conductance across locomotor muscles in association with improved o2 dynamics during heavy-intensity cycling transitions.
Description: This is an Open Access Article. It is published by Wiley under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/.
Version: Accepted for publication
DOI: 10.14814/phy2.13340
URI: https://dspace.lboro.ac.uk/2134/25847
Publisher Link: https://doi.org/10.14814/phy2.13340
ISSN: 2051-817X
Appears in Collections:Published Articles (Sport, Exercise and Health Sciences)

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