The effect of dietary nitrate supplementation on the spatial heterogeneity of quadriceps deoxygenation during heavy-intensity cycling

Abstract

This study investigated the influence of dietary inorganic nitrate (NO 3 −) supplementation on pulmonary O2 uptake (trueV˙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 two step cycle tests at a work rate equivalent to 50% of the difference between the gas exchange threshold and peak trueV˙O2 over separate 4‐day supplementation periods with NO 3 −‐rich (BR; providing 8.4 mmol NO 3 −∙day−1) and NO 3 −‐depleted (placebo; PLA) beetroot juice. Pulmonary trueV˙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 μmol/L, 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 μmol/L sec−1, P = 0.08). The trueV˙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 (r 2 = 0.62 and 0.66, P < 0.05). Dietary NO 3 − supplementation increased O2 diffusive conductance across locomotor muscles in association with improved trueV˙O2 dynamics during heavy‐intensity cycling transitions.

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

“…, James White Drinks, Ipswich, UK). The dose of BR administered was based on a previous dose-response study reporting an increase in plasma NO 3 and NO 2 concentration and peak reduction in systolic blood pressure following the ingestion of 8 mmol NO 3 -(Breese et al 2017;Cermak et al 2012;Lansley et al 2011;Kuennen et al 2015). The NO 3 -…”

Habitual exercise training in older adults offsets the age-related prolongation in leg vasodilator kinetics during single-limb lower body exercise

“…In the current study, BF and vasodilator responses were examined in the common femoral artery while the subject kicked at a cadence of 40 times per minute. Previous investigations into the BF and vasodilator kinetic responses to exercise have used a variety of cadences (20 -60 kicks per minute), examined responses bilaterally (30,38), or have utilized near-infrared spectroscopy to interrogate microvascular O 2 /deoxygenated dynamics (9,27,28). In this regard, the present study provides data on the kinetics of vasodilation in a large conduit artery that feeds into a larger skeletal muscle (quadriceps).…”

The benefits and risks of beetroot juice consumption: a systematic review

“…However, Kapil et al (2010) also found a significant systolic BP reduction after non-concentrated BRJ consumption (Kapil et al 2010). Several of these studies have in common that the largest reduction in systolic BP (SBP) occurs 3 h after BRJ consumption (Breese et al 2017;Kapil et al 2010;McDonagh et al 2018;Raubenheimer et al 2017). Burleigh et al (2019) found a peak SBP reduction after a couple of hours of BRJ ingestion, however, this reduction dissipated after 10 h, suggesting that daily doses of nitrate would be needed for a sustained BP reduction (Burleigh et al 2019).…”

“…Some studies show no significant beneficial effects of BRJ on VO 2 or VO 2 kinetics (Arnold et al 2015;Betteridge et al 2016;Boorsma, Whitfield, and Spriet 2014;Breese et al 2013;Breese et al 2017;Christensen, Nyberg, and Bangsbo 2013;Christensen et al 2017;MacLeod et al 2015;. It should be noted that the majority of the studies which did not establish effects on VO 2 used "well-trained" or "elite" athletes as subjects (Arnold et al 2015;Boorsma, Whitfield, and Spriet 2014;Christensen, Nyberg, and Bangsbo 2013;MacLeod et al 2015).…”