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The purpose of this study was to investigate the effects of acute nitrate (NO 3 - )-rich beetroot juice ingestion on explosive and high-intensity exercise performance, oral microbiota composition, and cognitive flexibility (i.e., function), before and after maximal intermittent running exercise. Fifteen women team-sport athletes were assigned in a randomized, double-blind, crossover design to consume concentrated NO 3 - -depleted beetroot juice (PL; 0.1 mmol NO 3 - ) and NO 3 - -rich beetroot juice (BR; 12.0 mmol NO 3 - ) 2.5 h prior to performing a battery of exercise performance tasks and cognitive testing before and after the Yo-Yo intermittent recovery level 1 (YYIR1) running test. Resting plasma [NO 3 - ] and plasma nitrite ([NO 2 - ]) were elevated following BR (P < 0.001). BR did not impact global composition or relative abundance of taxa in the oral microbiome (P > 0.05) or cognitive flexibility before or after exercise (P > 0.05). There was no significant difference in performance during 20-m (PRE, PL: 4.38 ± 0.27 vs. BR: 4.38 ± 0.32 s; POST, PL: 4.45 ± 0.29 vs. BR: 4.43 ± 0.35 s) and 10-m sprints (PRE, PL 2.78 ± 0.15 vs. BR 2.79 ± 0.18 s; POST, PL: 2.82 ± 0.16 vs. BR: 2.81 ± 0.19 s), isokinetic handgrip dynamometry, medicine ball throw, horizontal countermovement jump, or YYIR1 (PL: 355 ± 163 m vs. BR: 368 ± 184 m) between BR and PL (P > 0.05). These findings indicate that acute dietary NO 3 - may not influence the oral microbiome, explosive and high-intensity exercise performance, or cognitive function in women team-sport athletes., Competing Interests: Declarations Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Ethics statement The studies involving human participants were reviewed and approved by Pepperdine University Institutional Review Board. The patients/participants provided their written informed consent to participate in this study., (© 2024. The Author(s).)

Cold exposure increases blood pressure (BP) and salivary flow rate (SFR). Increased cold-induced SFR would be hypothesized to enhance oral nitrate delivery for reduction to nitrite by oral anaerobes and to subsequently elevate plasma [nitrite] and nitric oxide bioavailability. We tested the hypothesis that dietary nitrate supplementation would increase plasma [nitrite] and lower BP to a greater extent in cool compared with normothermic conditions. Twelve males attended the laboratory on four occasions. Baseline measurements were completed at 28°C. Subsequently, participants ingested 140 mL of concentrated nitrate-rich (BR; ∼13 mmol nitrate) or nitrate-depleted (PL) beetroot juice. Measurements were repeated over 3 h at either 28°C (Norm) or 20°C (Cool). Mean skin temperature was lowered compared with baseline in PL-Cool and BR-Cool. SFR was greater in BR-Norm, PL-Cool, and BR-Cool than PL-Norm. Plasma [nitrite] at 3 h was higher in BR-Cool (592 ± 239 nM) versus BR-Norm (410 ± 195 nM). Systolic BP (SBP) at 3 h was not different between PL-Norm (117 ± 6 mmHg) and BR-Norm (113 ± 9 mmHg). SBP increased above baseline at 1, 2, and 3 h in PL-Cool but not BR-Cool. These results suggest that BR consumption is more effective at increasing plasma [nitrite] in cool compared with normothermic conditions and blunts the rise in BP following acute cool air exposure, which might have implications for attenuating the increased cardiovascular strain in the cold. NEW & NOTEWORTHY Compared with normothermic conditions, acute nitrate ingestion increased plasma [nitrite], a substrate for oxygen-independent nitric oxide generation, to a greater extent during cool air exposure. Systolic blood pressure was increased during cool air exposure in the placebo condition with this cool-induced blood pressure increase attenuated after acute nitrate ingestion. These findings improve our understanding of environmental factors that influence nitrate metabolism and the efficacy of nitrate supplementation to lower blood pressure.

Purpose: Dietary nitrate (NO 3 - ) supplementation can lower systolic blood pressure (SBP) and improve exercise performance. Salivary flow rate (SFR) and pH are key determinants of oral NO 3 - reduction and purported to peak in the afternoon. We tested the hypotheses that NO 3 - -rich beetroot juice (BR) would increase plasma [nitrite] ([NO 2 - ]), lower SBP and improve exercise performance to a greater extent in the afternoon (AFT) compared to the morning (MORN) and evening (EVE)., Method: Twelve males completed six experimental visits in a repeated-measures, crossover design. NO 3 - -depleted beetroot juice (PL) or BR (~ 13 mmol NO 3 - ) were ingested in the MORN, AFT and EVE. SFR and pH, salivary and plasma [NO 3 - ] and [NO 2 - ], brachial SBP and central SBP were measured pre and post supplementation. A severe-intensity exercise tolerance test was completed to determine cycling time to exhaustion (TTE)., Results: There were no between-condition differences in mean SFR or salivary pH. The elevation in plasma [NO 2 - ] after BR ingestion was not different between BR-MORN, BR-AFT and BR-EVE. Brachial SBP was unchanged following BR supplementation in all conditions. Central SBP was reduced in BR-MORN (- 3 ± 4 mmHg), BR-AFT (- 4 ± 3 mmHg), and BR-EVE (- 2 ± 3 mmHg), with no differences between timepoints. TTE was not different between BR and PL at any timepoint., Conclusion: Acute BR supplementation was ineffective at improving TTE and brachial SBP and similarly effective at increasing plasma [NO 2 - ] and lowering central SBP across the day, which may have implications for informing NO 3 - supplementation strategies., (© 2023. The Author(s).)

This systematic review and meta-analysis of randomized controlled trials examined whether dietary nitrate supplementation attenuates exercise-induced muscle damage (EIMD) and is reported according to the PRISMA guidelines. Medline and SPORTDiscus databases were searched from inception to June 2020. Inclusion criteria were studies in adult humans consuming inorganic nitrate before and after exercise and that measured markers implicated in the etiology of EIMD (muscle function, muscle soreness, inflammation, myocellular protein efflux, oxidative stress, range of motion) <168 h post. The Cochrane Collaboration risk of bias two tool was used to critically appraise the studies; forest plots were generated with random-effects models and standardized mean differences (SMD). Nine studies were included in the systematic review and six in the meta-analysis. All studies were rated to have some concerns for risk of bias. All trials in the meta-analysis provided nitrate as beetroot juice, which accelerated isometric strength recovery 72 h post-exercise (SMD: 0.54, p  = 0.01) and countermovement jump performance 24-72 h post-exercise (SMD range: 0.75-1.32, p <  0.03). Pressure pain threshold was greater with beetroot juice 48 (SMD: 0.58, p  = 0.03) and 72 h post-exercise (SMD: 0.61, p  = 0.02). Beetroot juice had no effect on markers of oxidative stress and creatine kinase ( p >  0.05), but c-reactive protein was higher vs. placebo at 48 h post-exercise (SMD: 0.55, p  = 0.03). These findings suggest that nitrate-rich beetroot juice may attenuate some markers of EIMD, but more large-scale controlled trials in elite athletes are needed.

This study tested the hypothesis that exposure to chlorine-sterilised pool water would impair oral nitrate reduction (ONR). ONR was assessed in elite swimmers before and after morning and afternoon pool-based training. Nonswimmers were only assessed in the morning. ONR was similar in swimmers and nonswimmers ( P  = 1.000) and unchanged before and after morning and afternoon training ( P  ≥ 0.341). Therefore, exposure to chlorinated pool water does not interfere with ONR. Novelty Exposure to chlorine-sterilised pool water does not impair oral nitrate reduction in elite swimmers.