Effects of a Short-Term High-Nitrate Diet on Exercise Performance.

Simone Porcelli,Michela Montorsi,Mauro Marzorati,Matteo Bonato,Lorenzo Pugliese,Antonio La Torre,Gaspare Pavei,Enrico Rejc,Letizia Rasica

doi:10.3390/nu8090534

Abstract

It has been reported that nitrate supplementation can improve exercise performance. Most of the studies have used either beetroot juice or sodium nitrate as a supplement; there is lack of data on the potential ergogenic benefits of an increased dietary nitrate intake from a diet based on fruits and vegetables. Our aim was to assess whether a high-nitrate diet increases nitric oxide bioavailability and to evaluate the effects of this nutritional intervention on exercise performance. Seven healthy male subjects participated in a randomized cross-over study. They were tested before and after 6 days of a high (HND) or control (CD) nitrate diet (~8.2 mmol∙day−1 or ~2.9 mmol∙day−1, respectively). Plasma nitrate and nitrite concentrations were significantly higher in HND (127 ± 64 µM and 350 ± 120 nM, respectively) compared to CD (23 ± 10 µM and 240 ± 100 nM, respectively). In HND (vs. CD) were observed: (a) a significant reduction of oxygen consumption during moderate-intensity constant work-rate cycling exercise (1.178 ± 0.141 vs. 1.269 ± 0.136 L·min−1); (b) a significantly higher total muscle work during fatiguing, intermittent sub-maximal isometric knee extension (357.3 ± 176.1 vs. 253.6 ± 149.0 Nm·s·kg−1); (c) an improved performance in Repeated Sprint Ability test. These findings suggest that a high-nitrate diet could be a feasible and effective strategy to improve exercise performance.

Highlights

Nitric oxide (NO) is a gaseous signaling molecule linked to a variety of physiological functions in mammalian cells, including the regulation of blood flow, mitochondrial biogenesis, excitation–contraction coupling, calcium handling, oxidative stress, and skeletal muscle repair [1].NO is produced endogenously via the L-arginine-NO pathway by the nitric oxide synthase (NOS)enzymes in nervous tissue, the cardiovascular system, and skeletal muscle [2,3].an alternative source of NO has recently been described [4]
We examined the effects of a diet ensuring a high nitrate intake on nitrate/nitrite plasma levels and exercise performance
Our results show that 6 days of a HND (~8.2 mmol·day−1 ), compared to a control diet (CD) (~2.9 mmol·day−1 ), induced a significant rise of plasma nitrate and nitrite concentrations

Summary

Introduction

Nitric oxide (NO) is a gaseous signaling molecule linked to a variety of physiological functions in mammalian cells, including the regulation of blood flow, mitochondrial biogenesis, excitation–contraction coupling, calcium handling, oxidative stress, and skeletal muscle repair [1].NO is produced endogenously via the L-arginine-NO pathway by the nitric oxide synthase (NOS)enzymes in nervous tissue, the cardiovascular system (by the endothelium), and skeletal muscle [2,3].an alternative source of NO has recently been described [4]. Nitric oxide (NO) is a gaseous signaling molecule linked to a variety of physiological functions in mammalian cells, including the regulation of blood flow, mitochondrial biogenesis, excitation–contraction coupling, calcium handling, oxidative stress, and skeletal muscle repair [1]. Inorganic nitrate (NO3 − ), ingested from dietary sources (e.g., beetroot) or pharmacologic compounds A growing body of evidence demonstrates that acute (2–3 h) and short term (3–6 days) pharmacological (e.g., sodium/potassium nitrate) or dietary (e.g., beetroot juice) NO3 − supplementation reduces whole body oxygen cost during moderate-intensity exercise, and improves exercise tolerance—at least in sedentary or moderately-trained subjects [6,7,8,9,10,11,12].

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