Dietary nitrate supplementation enhances high-intensity running performance in moderate normobaric hypoxia, independent of aerobic fitness

TLDR: Findings suggests that a high nitrate dose in the form of a BRJ supplement may improve running performance in individuals with a range of aerobic fitness levels conducting moderate and high-intensity exercise in a normobaric hypoxic environment.

About: This article is published in Nitric Oxide.The article was published on 2016-09-30 and is currently open access. It has received 47 citations till now. The article focuses on the topics: Aerobic exercise.

Figures

Figure 1 Exhaled NO (A), Plasma nitrite (B) and plasma nitrate (C) throughout experimental trials in the placebo (PLA) (dashed lines) and 297 nitrate-rich beetroot juice (BRJ) (solid lines) conditions. Values are mean ± SEM. * T ime points significantly different between BRJ and 298

Figure 2 1500 m TT performance following ingestion of placebo (PLA) or nitrate-rich beetroot juice (BRJ). 347 348 4. Discussion 349 Nitrate-rich beetroot juice has emerged as a popular ergogenic aid, although previous research 350 suggests that this supplement has limited effects in well-trained individuals (V̇O2max > 60 351 ml·kg-1·min-1). In contrast, the results of this study suggest that nitrate-rich beetroot juice may 352 reduce the O2 cost of exercise, elevate SaO2, and enhance 1500 m TT performance in 353 individuals across a range of different fitness levels exercising in moderate-normobar ic 354 hypoxia. These data have relevance for the thousands of recreational and competitive athletes 355 ascending to altitude each year for sporting purposes. 356

Table 1 Ratings of perceived exertion, heart rate, mean arterial blood pressure, oxygen consumption, and arterial oxygen saturation 329 throughout experimental trials in the placebo (PLA) and nitrate-rich beetroot juice (BRJ) conditions 330

Frequently asked questions

Q1. What correction was used to adjust for asphericity?

To adjust for asphericity, the Greinhouse Geisser 233 correction was applied for ε < 0.75, and the Huynh-Feldt correction was adopted for ε > 0.75. 

Q2. What are the contributions in "Dietary nitrate supplementation enhances high-intensity running performance in moderate normobaric hypoxia, independent of aerobic fitness" ?

In this paper, the effects of dietary nitrate supplementation were investigated in the context of mountain climbing. But the results were limited to the use of a single mountain top. 

Q3. How many stages did the participants complete?

148 Participants completed five to eight sub-maximal stages lasting three minutes, separated with 149 one minute recovery periods. 

Q4. How much was the treadmill used to approximate the energy cost of running?

Running speed was increased by 1 km·h-1 each stage, and a 1 % treadmill 151 gradient was applied to approximate the energetic cost of outdoor running [49]. 

Q5. How many days did the participants spend in the laboratory?

On the morning of each experimental session, participants arrived at the laboratory between 7 164 and 9 am following an overnight fast. 

Q6. What is the effect of nitrate supplementation on performance?

This suggests that nitrate supplementa t ion 75 may be more likely to enhance NO generation and therefore improve performance in hypoxia 76 relative to normoxia. 

Q7. What are the physiological mechanisms underlying the decreased VO2 382 after nit?

The physiological mechanisms underlying the decreased V̇O2 382 subsequent to nitrate supplementation have not been fully elucidated, but may be accounted for 383 by: a) an improvement in the efficiency of mitochondrial respiration [35] and/or b) enhanced 384 efficiency of muscle force production [7]. 

Q8. how long did nitrate supplementation take to improve TTE?

The time-trial duration employed in this study (< 6 minutes) was 478 considerably less than other investigations (~ 17 - 48 minutes) which have not observed an 479 ergogenic effect of nitrate supplementation in hypoxia [38–40], and may be important. 

Q9. What is the effect of nitrate on running performance in hypoxia?

In normoxia, Murphy and colleagues [63] reported lower RPE during 436 the first mile of a 5 km running TT, although others have reported no effect of nitrate 437 supplementation on RPE during sub-maximal and maximal exercise in hypoxia following 438 nitrate supplementation [37,38]. 

Q10. What is the effect of nitrate on hypoxic exercise performance?

in other studies, nitrate 81 supplementation has been shown both to improve [8,22,37] and have no effect [38–40] on 82 hypoxic exercise performance.