Dietary Nitrate Supplementation Improves Exercise Tolerance by Reducing Muscle Fatigue and Perceptual Responses

Abstract

The present study was designed to provide further insight into the mechanistic basis for the improved exercise tolerance following dietary nitrate supplementation. In a randomized, double-blind, crossover design, twelve recreationally active males completed a dynamic time-to-exhaustion test of the knee extensors after 5 days of consuming both nitrate-rich (NITRATE) and nitrate-depleted beetroot juice (PLACEBO). Participants who improved their time-to-exhaustion following NITRATE performed a time-matched trial corresponding to the PLACEBO exercise duration with another 5 days of dietary nitrate supplementation. This procedure was performed to obtain time-matched exercise trials with (NITRATE tm ) and without dietary nitrate supplementation (PLACEBO). Neuromuscular tests were performed before and after each time-matched condition. Muscle fatigue was quantified as percentage change in maximal voluntary torque from pre- to post-exercise (ΔMVT). Changes in voluntary activation (ΔVA) and quadriceps twitch torque (ΔPS100) were used to quantify central and peripheral factors of muscle fatigue, respectively. Muscle oxygen saturation, quadriceps muscle activity as well as perceptual data (i.e., perception of effort and leg muscle pain) were recorded during exercise. Time-to-exhaustion was improved with NITRATE (12:41 ± 07:18 min) compared to PLACEBO (09:03 ± 04:18 min; P = 0.010). NITRATE tm resulted in both lower ΔMVT and ΔPS100 compared to PLACEBO ( P = 0.002; P = 0.001, respectively). ΔVA was not different between conditions ( P = 0.308). NITRATE tm resulted in reduced perception of effort and leg muscle pain. Our findings extend the mechanistic basis for the improved exercise tolerance by showing that dietary nitrate supplementation (i) attenuated the development of muscle fatigue by reducing the exercise-induced impairments in contractile muscle function; and (ii) lowered the perception of both effort and leg muscle pain during exercise.

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

“…This study also found that no mean differences were observed for fastest sprint time or fatigue index after BRJ consumption (Clifford, Bell, et al 2016;Clifford, Berntzen, et al 2016). Some studies have shown a reduction in muscle pain and fatigue associated with exercise induced muscle damage and reduced after with BRJ supplementation Husmann et al 2019). Furthermore, Clifford, Bell, et al (2017) published a study which stated that supplementation of nitrate rich BRJ does not negatively influence acute muscular adaptations after eccentric exercise (Clifford, Bell, et al 2017).…”

“…Since the metabolic perturbations occurring in (mainly type II) muscle fibers may be linked to the fatigue process, BRJ may delay the onset of fatigue by increasing PO 2 mv (Ferguson et al 2015). Indeed, Hoon et al (2015) found that four-day BRJ supplementation in healthy individuals decreased muscular fatigue in conditions of reduced blood flow during exhaustive exercise (Hoon et al 2015), and Husmann et al (2019) found reduced perceived effort and muscle pain after five-day BRJ ingestion (Husmann et al 2019). Additionally, several studies have found that BRJ improves exercise tolerance or rate of perceived exhaustion in normoxia (Aucouturier et al 2015;Bailey et al 2015;Balsalobre-Fern andez et al 2018;Breese et al 2013;Wylie, Kelly, Fulford, et al 2013) as well as hypoxia (Kelly et al 2014;Vanhatalo et al 2011).…”

Acute Effects of Beetroot Juice Supplements on Resistance Training: A Randomized Double-Blind Crossover

“…Several studies have assessed the effect of BJ supplementation on RPE. Although some authors have reported improved performance without any significant impact on RPE [ 12 , 14 , 55 ], others have shown lower RPE values [ 56 , 57 , 58 ]. To the authors’ knowledge, there is only one study that recorded the effect of BJ on RPE during RT [ 14 ]; Mosher et al [ 14 ] found that RPE during muscular endurance in RT was not significantly affected by 6 days of dietary nitrate supplementation.…”

Dietary Nitrate Protects Against Skin Flap Ischemia-Reperfusion Injury in Rats via Modulation of Antioxidative Action and Reduction of Inflammatory Responses

“…Nitrite is then converted to NO and nitrogen oxides in blood and tissues via multiple pathways (Bryan, 2006). Many studies have demonstrated the benefits of dietary nitrate, which may boost the nitrate-nitrite-NO pathway in the body (Lundberg et al, 2011a;Sindler et al, 2014b;Husmann et al, 2019). This distinct alternative pathway for NO generation is independent of NO synthase (NOS).…”