Dietary nitrate supplementation enhances short but not longer duration running time-trial performance

Abstract

TT performance between conditions (2643.1 ± 324. 1 vs. 2649.9 ± 319.8 s, P > 0.05). Conclusion Acute BRJ supplementation significantly enhanced 1500 m, but not 10,000 m TT performance. These findings suggest that BRJ might be ergogenic during shorter distance TTs which allow for a high work rate, but not during longer distance TTs, completed at a lower work rate. ) supplementation on physiological functioning and exercise performance in trained runners/triathletes conducting short and longer-distance treadmill running time-trials (TT). Method Eight trained male runners or triathletes completed four exercise performance tests comprising a 10 min warm up followed by either a 1500 or 10,000 m treadmill TT. Exercise performance tests were preceded 3 h before the exercise by supplementation with either 140 ml concentrated nitrate-rich (~12.5 mmol nitrate) (BRJ) or nitratedeplete (~0.01 mmol nitrate) (PLA) beetroot juice. Results BRJ supplementation significantly elevated plasma [NO 2 − ] (P < 0.05). Resting blood pressure and exercise V O 2 were not significantly different between BRJ and PLA (P > 0.05). However, post-exercise blood [lactate] was significantly greater in BRJ following the 1500 m TT (6.6 ± 1.2 vs. 6.1 ± 1.5 mM; P < 0.05), but not significantly different between conditions in the 10,000 m TT (P > 0.05). Performance in the 1500 m TT was significantly faster in BRJ vs. PLA (319.6 ± 36.2 vs. 325.7 ± 38.8 s; P < 0.05). Conversely, there was no significant difference in 10,000 m Communicated by Keywords

Effects of Dietary Nitrate Supplementation on Physiological Responses, Cognitive Function, and Exercise Performance at Moderate and Very-High Simulated Altitude

“…In the present investigation, plasma [${\text{NO}}_2^{-}$] was significantly elevated consequent to ${\text{NO}}_3^{-}$ supplementation, which substantiates previous research in this area (Webb et al, 2008; Bailey et al, 2009; Vanhatalo et al, 2010, 2011; Wylie et al, 2013; Shannon et al, 2016, 2017). NO generation via L-arginine appears to be blunted in hypoxic conditions (Shaul et al, 1993; Fish et al, 2007).…”

“…However, in the present study there was no apparent difference in resting MAP assessed prior to simulated altitude exposure between BRJ and PLA. This is also similar to the findings of a recent study by our group, in which trained runners/triathletes showed no change in MAP following administration of an identical ${\text{NO}}_3^{-}$ dose, despite substantial increases in plasma [${\text{NO}}_2^{-}$] (Shannon et al, 2017). Recently, Ashworth et al (2015) reported a significant positive relationship between baseline BP and the change in BP following ingestion of a high-${\text{NO}}_3^{-}$ diet.…”

Human skeletal muscle nitrate store: influence of dietary nitrate supplementation and exercise

“…Acute nitrate supplementation has been reported to be ergogenic in some (e.g. Lansley et al 2011;Shannon et al 2017) but not all (e.g. Kelly et al 2014) previous studies using a similar design.…”

Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O2 uptake

“…Ϫ supplementation, plasma NO 2 Ϫ concentration ([NO 2 Ϫ ]) declines over the course of short duration moderate-and severe-intensity exercise (32,50), as well as during repeated sprints (51,52,59). Indeed, this decline in plasma [NO 2 Ϫ ] with time during exercise, which may reflect the use of nitrite as a "substrate" for NO production, is correlated with enhanced high-intensity exercise performance following NO 3 Ϫ supplementation (52,59).…”

“…Ϫ ] dynamics. Indeed, previous research has reported significant reductions in plasma [NO 2 Ϫ ] following high-intensity exercise of shorter duration (32,50,52,60). It is possible that the greater degree of hypoxia and acidosis that would be expected to develop in skeletal muscle during highintensity exercise, such as TT, compared with moderate-intensity exercise, facilitates or dictates a greater reduction of NO 2…”