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- Title
Influence of acute dietary nitrate supplementation timing on nitrate metabolism, central and peripheral blood pressure and exercise tolerance in young men.
- Authors
Rowland, Samantha N.; James, Lewis J.; O'Donnell, Emma; Bailey, Stephen J.
- Abstract
Purpose: Dietary nitrate (NO3−) supplementation can lower systolic blood pressure (SBP) and improve exercise performance. Salivary flow rate (SFR) and pH are key determinants of oral NO3− reduction and purported to peak in the afternoon. We tested the hypotheses that NO3−-rich beetroot juice (BR) would increase plasma [nitrite] ([NO2−]), 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. NO3−-depleted beetroot juice (PL) or BR (~ 13 mmol NO3−) were ingested in the MORN, AFT and EVE. SFR and pH, salivary and plasma [NO3−] and [NO2−], 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 [NO2−] 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 [NO2−] and lowering central SBP across the day, which may have implications for informing NO3− supplementation strategies.
- Subjects
EXERCISE tolerance; BLOOD pressure; DIETARY supplements; SYSTOLIC blood pressure; METABOLISM
- Publication
European Journal of Applied Physiology, 2024, Vol 124, Issue 5, p1381
- ISSN
1439-6319
- Publication type
Article
- DOI
10.1007/s00421-023-05369-z