After running 230 kilometers, elite runners show higher levels of nitrite in their blood, which indicates increased production of nitric oxide—a molecule that helps blood vessels relax and improve blood flow.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Whether nitrite elevation after ultramarathons is a consistent physiological adaptation across different populations and whether it correlates with improved vascular function.
A systematic review and meta-analysis of all studies measuring plasma or RBC nitrite in endurance athletes before and after races >200 km, pooling standardized mean differences and assessing heterogeneity by race duration, climate, and training status.
Whether enhancing nitric oxide bioavailability before an ultramarathon improves microvascular perfusion or reduces fatigue.
A double-blind RCT of 80 elite runners assigned to receive either a nitrate-rich beetroot juice supplement or placebo for 7 days before a 230-km race, measuring plasma nitrite, microvascular flow via near-infrared spectroscopy, and time to fatigue during the race.
Whether runners with higher post-race nitrite levels recover faster or have lower incidence of vascular events over time.
A prospective cohort study following 200 ultramarathon runners for 5 years, measuring plasma nitrite after each race and tracking cardiovascular events, endothelial function, and recovery metrics.
Whether baseline nitrite levels predict post-race nitrite response in elite runners.
A single-timepoint cross-sectional study measuring resting plasma nitrite in 150 elite ultramarathon runners and correlating it with their post-race nitrite increase after a 230-km race.
Whether nitrite elevation is absent or abnormal in runners with endothelial dysfunction or nitric oxide synthesis disorders.
A case series of 10 ultramarathon runners with known endothelial dysfunction (e.g., severe hypertension or diabetes) who complete a 230-km race, measuring plasma nitrite response compared to healthy controls.