Beetroot Juice Supplementation Improves High-Intensity Intermittent Type Exercise Performance in Trained Soccer Players.

Luc Van Loon,Kristin Jonvik,Jean Nyakayiru,Philippe Pinckaers,Jorn Trommelen,Lex Verdijk,Joan Senden

doi:10.3390/nu9030314

Abstract

It has been shown that nitrate supplementation can enhance endurance exercise performance. Recent work suggests that nitrate ingestion can also increase intermittent type exercise performance in recreational athletes. We hypothesized that six days of nitrate supplementation can improve high-intensity intermittent type exercise performance in trained soccer players. Thirty-two male soccer players (age: 23 ± 1 years, height: 181 ± 1 m, weight: 77 ± 1 kg, playing experience: 15.2 ± 0.5 years, playing in the first team of a 2nd or 3rd Dutch amateur league club) participated in this randomized, double-blind cross-over study. All subjects participated in two test days in which high-intensity intermittent running performance was assessed using the Yo-Yo IR1 test. Subjects ingested nitrate-rich (140 mL; ~800 mg nitrate/day; BR) or a nitrate-depleted beetroot juice (PLA) for six subsequent days, with at least eight days of wash-out between trials. The distance covered during the Yo-Yo IR1 was the primary outcome measure, while heart rate (HR) was measured continuously throughout the test, and a single blood and saliva sample were collected just prior to the test. Six days of BR ingestion increased plasma and salivary nitrate and nitrite concentrations in comparison to PLA (p < 0.001), and enhanced Yo-Yo IR1 test performance by 3.4 ± 1.3% (from 1574 ± 47 to 1623 ± 48 m; p = 0.027). Mean HR was lower in the BR (172 ± 2) vs. PLA trial (175 ± 2; p = 0.014). Six days of BR ingestion effectively improves high-intensity intermittent type exercise performance in trained soccer players.

Highlights

While nitrate and nitrite were previously considered inert byproducts of the nitric oxide (NO) metabolism, recent insights suggest that nitrate can serve as a precursor for NO through the nitrate -> nitrite -> NO-pathway [1]
We have previously shown that nitrate-rich beetroot juice ingestion can increase oxygen efficiency during submaximal cycling exercise, but that it can improve time trial performance in moderately trained cyclists and triathletes [5]
Ingestion of beetroot juice (BR) for six subsequent days resulted in elevated nitrate concentrations when compared to PLA, in both plasma (Figure 1A) and saliva (Figure 1C)

Summary

Introduction

While nitrate and nitrite were previously considered inert byproducts of the nitric oxide (NO) metabolism, recent insights suggest that (dietary) nitrate can serve as a precursor for NO through the nitrate -> nitrite -> NO-pathway [1]. Different studies have shown that both plasma nitrate and nitrite concentrations increase following dietary nitrate supplementation in a dose-dependent manner [2,3]. These elevations in plasma concentrations have in turn been associated with improvements in exercise performance, suggesting ergogenic benefits from activation of the nitrate to NO pathway [4,5,6]. We have previously shown that nitrate-rich beetroot juice ingestion can increase oxygen efficiency during submaximal cycling exercise, but that it can improve time trial performance in moderately trained cyclists and triathletes [5]. This work, in line with others [6,9], has established a functional benefit of dietary nitrate supplementation on exercise performance

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Results

Conclusion