|Does the vasodilatory effect of nitrates have a direct ergogenic effect that correlates with increases in blood flow?|
In said study, Julien Aucouturier et al. tried to determine whether 3 days on NO3-rich beetroot juice would boost the tolerance to supra-maximal intermittent exercise.
To this ends, the French researchers had their subjects, who were not previously engaged in any form of intense endurance exercise perform a standardized exercise test, which consisted of 15-second exercise periods at 170% of the maximal aerobic power interspersed with 30-second passive recovery
periods, to failure.
|Figure 1: Overview of the study design (Aucouturier. 2015).|
|Figure 2: Individual data points for the increase in reps (=number of intervals to exhaustion) and markers of potential mechanisms that trigger this increase, i.e. ventilation (right, top) & oxygen uptake (right, bottom | Aucouturier. 2015)|
Before we get back to the mechanism I hinted at in the introduction, already, I want to highlight one last thing that follows from the previously highlighted result: If "only" more than 50% of the subjects benefited from the NO3- almost 50% of them didn't benefit and that's not exactly news when it comes to beetroot juice and nitrate supplementation. Previous studies showed similarly conflicting results with some suggesting that the training status of the subjects may be a significant modifier (athletes may benefit less than couch potatoes), but the reason for the differentials response of the subjects is something to investigate in another study.
- Aucouturier, Julien, et al. "Effect of dietary nitrate supplementation on tolerance to supramaximal intensity intermittent exercise." Nitric Oxide (2015).