Influence of nitrate supplementation on endurance cyclic sports performance: A systematic review 

This 2020 systematic review was conducted to clarify the use and effects of nitrate as a dietary supplement in endurance athletes trained in cyclic sports (repetitive movement sports).  Statistically significant ergogenic results were obtained in eight (29.63%) of the 27 studies investigated, with significant results obtained for cardiorespiratory parameters and performance measures. Improvement in exercise tolerance was obtained, which could help with exhaustion over time, while the improvement in exercise economics was not as clear. The acute dose is around 6-12.4 mmol/day of nitrate administered two to three hours before the activity, with the same amount given as a chronic dose over six to 15 days.  

References:

Lorenzo Calvo J, Alorda-Capo F, Pareja-Galeano H, Jiménez SL. Influence of Nitrate Supplementation on Endurance Cyclic Sports Performance: A Systematic Review. Nutrients. 2020 Jun 17;12(6):1796. doi: 10.3390/nu12061796. PMID: 32560317; PMCID: PMC7353291. https://pubmed.ncbi.nlm.nih.gov/32560317/