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

Abstract

Nitrate-rich beetroot juice (BR) supplementation has been shown to increase biomarkers of nitric oxide availability with implications for the physiological responses to exercise. We hypothesized that BR supplementation before and during prolonged moderate-intensity exercise would maintain an elevated plasma nitrite concentration ([[Formula: see text]]), attenuate the expected progressive increase in V̇o over time, and improve performance in a subsequent time trial (TT). In a double-blind, randomized, crossover design, 12 men completed 2 h of moderate-intensity cycle exercise followed by a 100-kJ TT in three conditions: 1) BR before and 1 h into exercise (BR + BR); 2) BR before and placebo (PL) 1 h into exercise (BR + PL); and 3) PL before and 1 h into exercise (PL + PL). During the 2-h moderate-intensity exercise bout, plasma [[Formula: see text]] declined by ~17% in BR + PL but increased by ~8% in BR + BR such that, at 2 h, plasma [[Formula: see text]] was greater in BR + BR than both BR + PL and PL + PL ( P < 0.05). V̇o was not different among conditions over the first 90 min of exercise but was lower at 120 min in BR + BR (1.73 ± 0.24 l/min) compared with BR + PL (1.80 ± 0.21 l/min; P = 0.08) and PL + PL (1.83 ± 0.27 l/min; P < 0.01). The decline in muscle glycogen concentration over the 2-h exercise bout was attenuated in BR + BR (~28% decline) compared with BR + PL (~44% decline) and PL + PL (~44% decline; n = 9, P < 0.05). TT performance was not different among conditions ( P > 0.05). BR supplementation before and during prolonged moderate-intensity exercise attenuated the progressive rise in V̇o over time and appeared to reduce muscle glycogen depletion but did not enhance subsequent TT performance. NEW & NOTEWORTHY We show for the first time that ingestion of nitrate during exercise preserves elevated plasma [nitrite] and negates the progressive rise in O uptake during prolonged moderate-intensity exercise.

Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers

“…Issues for future study • Individual responsiveness to nitrate supplementation in distance running, including the effect of athletes' caliber as it seems less effective in elite athletes (Jonvik et al, 2015) • Effect of protocols involving intake during distance events to maintain elevated plasma nitrite concentrations (Tan et al, 2018) • Interaction with other supplements-CHO, caffeine, etc.…”

Effects of a single dose of beetroot juice on cycling time trial performance at ventilatory thresholds intensity in male triathletes

“…In this study, VO 2 steady-state of moderate exercise intensity was reduced significantly after ingestion of 16.8 mmol of NO 3 − , tended to be lower after intake of 8.4 mmol NO 3 − , and was unaffected by 4.2 mmol of NO 3 − [ 37 ]. Higher doses of BJ supplementation (2 × 70 mL doses per day, ~ 6.2 mmol of NO 3 − per 70 mL) before and during prolonged moderate-intensity exercise might be necessary to attenuate the progressive rise in VO 2 and reduce muscle glycogen depletion [ 52 ], improving mechanical efficiency during a prolonged constant-load test at VT1 intensity. Further, IOC consensus statement concludes that longer periods (> 3 days) of NO 3 − supplementation could increase sport performance in highly-trained athletes [ 22 ].…”

The benefits and risks of beetroot juice consumption: a systematic review

“…In several studies, ingestion of BRJ was found to significantly decrease VO 2 , regardless of the duration of BRJ consumption and type of intervention Kelly et al 2014;Kuennen et al 2015;Lansley, Winyard, Fulford, et al 2011;Masschelein et al 2012;Muggeridge et al 2013Muggeridge et al , 2014Rienks et al 2015;Tan et al 2018;Thompson et al 2017;Vanhatalo et al 2010;Whitfield et al 2016;Wylie, Kelly, Fulford, et al 2013). Tan et al (2018) found that a 3day supplementation of BRJ before, and ingestion of BRJ during moderate-intensity exercise attenuated the increase in VO 2 that normally accompanies sportive performance, compared to placebo (Tan et al 2018). Additionally, this study reports that BRJ reduced the amount of glycogen depletion during exercise by 16% as compared to the placebo, which indicates that the metabolic demand of the muscle is decreased.…”

“…Additionally, this study reports that BRJ reduced the amount of glycogen depletion during exercise by 16% as compared to the placebo, which indicates that the metabolic demand of the muscle is decreased. Both the lower VO 2 and the reduced glycogen depletion could be caused by either an improvement in mitochondrial efficiency or in contractile efficiency of skeletal muscle (Tan et al 2018). However, there is no consensus on the precise mechanism.…”

“…It should be noted that the majority of the studies which did not establish effects on VO 2 used "well-trained" or "elite" athletes as subjects (Arnold et al 2015;Boorsma, Whitfield, and Spriet 2014;Christensen, Nyberg, and Bangsbo 2013;MacLeod et al 2015). In contrast, studies that demonstrate the positive effects were performed with healthy and recreationally active individuals (Breese et al 2013;Kelly et al 2014;Lansley, Winyard, Fulford, et al 2011;Masschelein et al 2012;Rienks et al 2015;Tan et al 2018;Vanhatalo et al 2010;Whitfield et al 2016), or "trained", but not "well-trained" subjects Muggeridge et al 2013Muggeridge et al , 2014Thompson et al 2017). This may be due to the fact that training has a modifying effect on the body, for example by increasing nitric oxide synthase levels, an enzyme that is used to form NO from L-arginine.…”