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Silva KVC, Costa BD, Gomes AC, Saunders B, Mota JF. Factors that Moderate the Effect of Nitrate Ingestion on Exercise Performance in Adults: A Systematic Review with Meta-Analyses and Meta-Regressions. Adv Nutr 2022; 13:1866-1881. [PMID: 35580578 PMCID: PMC9526841 DOI: 10.1093/advances/nmac054] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 11/16/2021] [Accepted: 05/09/2022] [Indexed: 01/28/2023] Open
Abstract
To identify how variables such as exercise condition, supplementation strategy, participant characteristics and demographics, and practices that control oral microbiota diversity could modify the effect of inorganic nitrate ingestion (as nitrate salt supplements, beetroot juice, and nitrate-rich vegetables) on exercise performance, we conducted a systematic review with meta-analysis. Studies were identified in PubMed, Embase, and Cochrane databases. Eligibility criteria included randomized controlled trials assessing the effect of inorganic nitrate on exercise performance in healthy adults. To assess the variation in effect size, we used meta-regression models for continuous variables and subgroup analysis for categorical variables. A total of 123 studies were included in this meta-analysis, comprising 1705 participants. Nitrate was effective for improving exercise performance (standardized mean difference [SMD]: 0.101; 95% CI: 0.051, 0.151, P <0.001, I2 = 0%), although nitrate salts supplementation was not as effective (P = 0.629) as ingestion via beetroot juice (P <0.001) or a high-nitrate diet (P = 0.005). Practices that control oral microbiota diversity influenced the nitrate effect, with practices harmful to oral bacteria decreasing the ergogenic effect of nitrate. The ingestion of nitrate was most effective for exercise lasting between 2 and 10 min (P <0.001). An inverse dose-response relation between the fraction of inspired oxygen and the effect size (coefficient: -0.045, 95% CI: -0.085, -0.005, P = 0.028) suggests that nitrate was more effective in increasingly hypoxic conditions. There was a dose-response relation for acute administration (P = 0.049). The most effective acute dose was between 5 and 14.9 mmol provided ≥150 min prior to exercise (P <0.001). An inverse dose-response for protocols ≥2 d was observed (P = 0.025), with the optimal dose between 5 and 9.9 mmol·d-1 (P <0.001). Nitrate, via beetroot juice or a high-nitrate diet, improved exercise performance, in particular, in sessions lasting between 2 and 10 min. Ingestion of 5-14.9 mmol⋅d-1 taken ≥150 min prior to exercise appears optimal for performance gains and athletes should be aware that practices controlling oral microbiota diversity may decrease the effect of nitrate.
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Affiliation(s)
| | - Breno Duarte Costa
- Applied Physiology and Nutrition Research Group, Rheumatology Division, Faculty of Medicine, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Aline Corado Gomes
- Faculty of Nutrition, Federal University of Goiás (UFG), Goiania, Goiás, Brazil
| | - Bryan Saunders
- Applied Physiology and Nutrition Research Group, Rheumatology Division, Faculty of Medicine, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
- Institute of Orthopaedics and Traumatology, Faculty of Medicine FMUSP, University of São Paulo, São Paulo, Brazil
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d'Unienville NMA, Blake HT, Coates AM, Hill AM, Nelson MJ, Buckley JD. Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials. J Int Soc Sports Nutr 2021; 18:76. [PMID: 34965876 PMCID: PMC8715640 DOI: 10.1186/s12970-021-00472-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/23/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Increasing nitric oxide bioavailability may induce physiological effects that enhance endurance exercise performance. This review sought to evaluate the performance effects of consuming foods containing compounds that may promote nitric oxide bioavailability. METHODS Scopus, Web of Science, Ovid Medline, EMBASE and SportDiscus were searched, with included studies assessing endurance performance following consumption of foods containing nitrate, L-arginine, L-citrulline or polyphenols. Random effects meta-analysis was conducted, with subgroup analyses performed based on food sources, sex, fitness, performance test type and supplementation protocol (e.g. duration). RESULTS One hundred and eighteen studies were included in the meta-analysis, which encompassed 59 polyphenol studies, 56 nitrate studies and three L-citrulline studies. No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24). Trivial but significant benefits were demonstrated for consumption of nitrate and polyphenol-rich foods (SMD=0.15 and 0.17, respectively, p<0.001), including performance in time-trial, time-to-exhaustion and intermittent-type tests, and following both acute and multiple-day supplementation, but no effect of nitrate or polyphenol consumption was found in females. Among nitrate-rich foods, beneficial effects were seen for beetroot, but not red spinach or Swiss chard and rhubarb. For polyphenol-rich foods, benefits were found for grape, (nitrate-depleted) beetroot, French maritime pine, Montmorency cherry and pomegranate, while no significant effects were evident for New Zealand blackcurrant, cocoa, ginseng, green tea or raisins. Considerable heterogeneity between polyphenol studies may reflect food-specific effects or differences in study designs and subject characteristics. Well-trained males (V̇O2max ≥65 ml.kg.min-1) exhibited small, significant benefits following polyphenol, but not nitrate consumption. CONCLUSION Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent. Highly trained endurance athletes do not appear to benefit from consuming nitrate-rich foods but may benefit from polyphenol consumption. Further research into food sources, dosage and supplementation duration to optimise the ergogenic response to polyphenol consumption is warranted. Further studies should evaluate whether differential sex-based responses to nitrate and polyphenol consumption are attributable to physiological differences or sample size limitations. OTHER The review protocol was registered on the Open Science Framework ( https://osf.io/u7nsj ) and no funding was provided.
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Affiliation(s)
- Noah M A d'Unienville
- Allied Health and Human Performance, University of South Australia, Adelaide, Australia. Noah.D'
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia. Noah.D'
| | - Henry T Blake
- Allied Health and Human Performance, University of South Australia, Adelaide, Australia
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia
| | - Alison M Coates
- Allied Health and Human Performance, University of South Australia, Adelaide, Australia
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia
| | - Alison M Hill
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia
- Clinical and Health Sciences, University of South Australia, Adelaide, Australia
| | - Maximillian J Nelson
- Allied Health and Human Performance, University of South Australia, Adelaide, Australia
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia
| | - Jonathan D Buckley
- Allied Health and Human Performance, University of South Australia, Adelaide, Australia
- Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, Australia
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de Sousa MV, Lundsgaard AM, Christensen PM, Christensen L, Randers MB, Mohr M, Nybo L, Kiens B, Fritzen AM. Nutritional optimization for female elite football players-topical review. Scand J Med Sci Sports 2021; 32 Suppl 1:81-104. [PMID: 34865242 DOI: 10.1111/sms.14102] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/13/2021] [Accepted: 11/17/2021] [Indexed: 11/29/2022]
Abstract
Women's football is an intermittent sport characterized by frequent intense actions throughout the match. The high number of matches with limited recovery time played across a long competitive season underlines the importance of nutritional strategies to meet these large physical demands. In order to maximize sport performance and maintain good health, energy intake must be optimal. However, a considerable proportion of female elite football players does not have sufficient energy intake to match the energy expenditure, resulting in low energy availability that might have detrimental physiologic consequences and impair performance. Carbohydrates appear to be the primary fuel covering the total energy supply during match-play, and female elite football players should aim to consume sufficient carbohydrates to meet the requirements of their training program and to optimize the replenishment of muscle glycogen stores between training bouts and matches. However, several macro- and micronutrients are important for ensuring sufficient energy and nutrients for performance optimization and for overall health status in female elite football players. The inadequacy of macro-and micronutrients in the diet of these athletes may impair performance and training adaptations, and increase the risk of health disorders, compromising the player's professional career. In this topical review, we present knowledge and relevant nutritional recommendations for elite female football players for the benefit of sports nutritionists, dietitians, sports scientists, healthcare specialists, and applied researchers. We focus on dietary intake and cover the most pertinent topics in sports nutrition for the relevant physical demands in female elite football players as follows: energy intake, macronutrient and micronutrient requirements and optimal composition of the everyday diet, nutritional and hydration strategies to optimize performance and recovery, potential ergogenic effects of authorized relevant supplements, and future research considerations.
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Affiliation(s)
- Maysa V de Sousa
- Laboratory of Medical Investigation, LIM-18, Endocrinology Division, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Anne-Marie Lundsgaard
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Lars Christensen
- Department of Nutrition, Exercise and Sports, Section of Obesity Research, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Morten B Randers
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark.,School of Sport Sciences, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
| | - Magni Mohr
- Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark.,Centre of Health Science, Faculty of Health, University of the Faroe Islands, Tórshavn, Faroe Islands
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, Section of Integrative Physiology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Bente Kiens
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Andreas M Fritzen
- Department of Nutrition, Exercise and Sports, Section of Molecular Physiology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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Macuh M, Knap B. Effects of Nitrate Supplementation on Exercise Performance in Humans: A Narrative Review. Nutrients 2021; 13:3183. [PMID: 34579061 PMCID: PMC8465461 DOI: 10.3390/nu13093183] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 09/04/2021] [Accepted: 09/10/2021] [Indexed: 12/20/2022] Open
Abstract
Nitrates have become increasingly popular for their potential role as an ergogenic aid. The purpose of this article was to review the current scientific evidence of nitrate supplementation on human performance. The current recommendation of nitrate supplementation is discussed, as well as possible health complications associated with nitrate intake for athletes, and dietary strategies of covering nitrate needs through sufficient intake of nitrate-rich foods alone are presented. Pubmed, Scopus, and Web of Science were searched for articles on the effects of nitrate supplementation in humans. Nitrates are an effective ergogenic aid when taken acutely or chronically in the range of ~5-16.8 mmol (~300-1041 mg) 2-3 h before exercise and primarily in the case of exercise duration of ~10-17 min in less trained individuals (VO2max < 65 mL/kg/min). Nitrate needs are most likely meet by ingesting approximately 250-500 g of leafy and root vegetables per day; however, dietary supplements might represent a more convenient and accurate way of covering an athlete's nitrate needs. Athletes should refrain from mouthwash usage when nitrate supplementation benefits are desired. Future research should focus on the potential beneficial effects of nitrate supplementation on brain function, possible negative impacts of chronic nitrate supplementation through different nitrate sources, and the effectiveness of nitrate supplementation on strength and high-intensity intermittent exercise.
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Affiliation(s)
- Matjaž Macuh
- Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana; Jamnikarjeva 10, 1000 Ljubljana, Slovenia
| | - Bojan Knap
- Department of Nephrology, University Medical Centre Ljubljana, Zaloška 7, 1000 Ljubljana, Slovenia;
- Faculty of Medicine, University of Ljubljana, Korytkova ulica 2, 1000 Ljubljana, Slovenia
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Cramer MN, Hieda M, Huang M, Moralez G, Crandall CG. Dietary nitrate supplementation does not influence thermoregulatory or cardiovascular strain in older individuals during severe ambient heat stress. Exp Physiol 2020; 105:1730-1741. [PMID: 32816341 DOI: 10.1113/ep088834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 08/17/2020] [Indexed: 12/16/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does dietary nitrate supplementation with beetroot juice attenuate thermoregulatory and cardiovascular strain in older adults during severe heat stress? What is the main finding and its importance? A 7-day nitrate supplementation regimen lowered resting mean arterial pressure in thermoneutral conditions. During heat stress, core and mean skin temperatures, vasodilatory responses, sweat loss, heart rate and left ventricular function were unchanged, and mean arterial pressure was only transiently reduced, post-supplementation. These data suggest nitrate supplementation with beetroot juice does not mitigate thermoregulatory or cardiovascular strain in heat-stressed older individuals. ABSTRACT This study tested the hypothesis that dietary nitrate supplementation with concentrated beetroot juice attenuates thermoregulatory and cardiovascular strain in older individuals during environmental heat stress. Nine healthy older individuals (six females, three males; aged 67 ± 5 years) were exposed to 42.5 ± 0.1°C and 34.0 ± 0.5% relative humidity conditions for 120 min before (CON) and after 7 days of dietary nitrate supplementation with concentrated beetroot juice (BRJ; 280 ml, ∼16.8 mmol of nitrate daily). Core and skin temperatures, body mass changes (indicative of whole-body sweat loss), skin blood flow and cutaneous vascular conductance, forearm blood flow and vascular conductance, heart rate, arterial blood pressures and indices of cardiac function were measured. The 7-day beetroot juice regimen increased plasma nitrate/nitrite levels from 27.4 ± 15.2 to 477.0 ± 102.5 μmol l-1 (P < 0.01) and lowered resting mean arterial pressure from 90 ± 7 to 83 ± 10 mmHg at baseline under thermoneutral conditions (P = 0.02). However, during subsequent heat stress, no differences in core and skin temperatures, skin blood flow and vascular conductance, forearm blood flow and vascular conductance, whole-body sweat loss, heart rate, and echocardiographic indices of systolic function and diastolic filling were evident following nitrate supplementation (all P > 0.05). Mean arterial pressure was lower in BRJ vs. CON during heat stress (treatment-by-time interaction: P = 0.02). Overall, these findings suggest that dietary nitrate supplementation with concentrated beetroot juice does not attenuate thermoregulatory or cardiovascular strain in older individuals exposed to severe ambient heat stress.
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Affiliation(s)
- Matthew N Cramer
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Michinari Hieda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,School of Medicine, Kyushu University, Fukuoka, Japan
| | - Mu Huang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gilbert Moralez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA.,Applied Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and University of Texas Southwestern Medical Center, Dallas, TX, USA
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6
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Zamani H, de Joode MEJR, Hossein IJ, Henckens NFT, Guggeis MA, Berends JE, de Kok TMCM, van Breda SGJ. The benefits and risks of beetroot juice consumption: a systematic review. Crit Rev Food Sci Nutr 2020; 61:788-804. [PMID: 32292042 DOI: 10.1080/10408398.2020.1746629] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Beetroot juice (BRJ) has become increasingly popular amongst athletes aiming to improve sport performances. BRJ contains high concentrations of nitrate, which can be converted into nitric oxide (NO) after consumption. NO has various functions in the human body, including a vasodilatory effect, which reduces blood pressure and increases oxygen- and nutrient delivery to various organs. These effects indicate that BRJ may have relevant applications in prevention and treatment of cardiovascular disease. Furthermore, the consumption of BRJ also has an impact on oxygen delivery to skeletal muscles, muscle efficiency, tolerance and endurance and may thus have a positive impact on sports performances. Aside from the beneficial aspects of BRJ consumption, there may also be potential health risks. Drinking BRJ may easily increase nitrate intake above the acceptable daily intake, which is known to stimulate the endogenous formation of N-nitroso compounds (NOC's), a class of compounds that is known to be carcinogenic and that may also induce several other adverse effects. Compared to studies on the beneficial effects, the amount of data and literature on the negative effects of BRJ is rather limited, and should be increased in order to perform a balanced risk assessment.
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Affiliation(s)
- H Zamani
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - M E J R de Joode
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - I J Hossein
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - N F T Henckens
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - M A Guggeis
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - J E Berends
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - T M C M de Kok
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
| | - S G J van Breda
- Department of Toxicogenomics, GROW-school for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands
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Pawlak-Chaouch M, Boissière J, Munyaneza D, Gamelin FX, Cuvelier G, Berthoin S, Aucouturier J. Beetroot Juice Does Not Enhance Supramaximal Intermittent Exercise Performance in Elite Endurance Athletes. J Am Coll Nutr 2019; 38:729-738. [DOI: 10.1080/07315724.2019.1601601] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Mehdi Pawlak-Chaouch
- Sport, Health and Society, URePSSS–Pluridisciplinary Research Unit, Lille University, Lille, France
| | - Julien Boissière
- Sport, Health and Society, URePSSS–Pluridisciplinary Research Unit, Lille University, Lille, France
| | - Désiré Munyaneza
- Sport, Health and Society, URePSSS–Pluridisciplinary Research Unit, Lille University, Lille, France
| | - François-Xavier Gamelin
- Sport, Health and Society, URePSSS–Pluridisciplinary Research Unit, Lille University, Lille, France
| | - Grégory Cuvelier
- Laboratory of Exercise and Movement, Provincial School of Hainaut (HEPH)-Condorcet, Tournai, Belgium
| | - Serge Berthoin
- Sport, Health and Society, URePSSS–Pluridisciplinary Research Unit, Lille University, Lille, France
| | - Julien Aucouturier
- Sport, Health and Society, URePSSS–Pluridisciplinary Research Unit, Lille University, Lille, France
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Nitrate supplementation improves physical performance specifically in non-athletes during prolonged open-ended tests: a systematic review and meta-analysis. Br J Nutr 2019; 119:636-657. [PMID: 29553034 DOI: 10.1017/s0007114518000132] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Nitrate (NO3 -) is an ergogenic nutritional supplement that is widely used to improve physical performance. However, the effectiveness of NO3 - supplementation has not been systematically investigated in individuals with different physical fitness levels. The present study analysed whether different fitness levels (non-athletes v. athletes or classification of performance levels), duration of the test used to measure performance (short v. long duration) and the test protocol (time trials v. open-ended tests v. graded-exercise tests) influence the effects of NO3 - supplementation on performance. This systematic review and meta-analysis was conducted and reported according to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. A systematic search of electronic databases, including PubMed, Web of Science, SPORTDiscus and ProQuest, was performed in August 2017. On the basis of the search and inclusion criteria, fifty-four and fifty-three placebo-controlled studies evaluating the effects of NO3 - supplementation on performance in humans were included in the systematic review and meta-analysis, respectively. NO3 - supplementation was ergogenic in non-athletes (mean effect size (ES) 0·25; 95 % CI 0·11, 0·38), particularly in evaluations of performance using long-duration open-ended tests (ES 0·47; 95 % CI 0·23, 0·71). In contrast, NO3 - supplementation did not enhance the performance of athletes (ES 0·04; 95 % CI -0·05, 0·15). After objectively classifying the participants into different performance levels, the frequency of trials showing ergogenic effects in individuals classified at lower levels was higher than that in individuals classified at higher levels. Thus, the present study indicates that dietary NO3 - supplementation improves physical performance in non-athletes, particularly during long-duration open-ended tests.
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Chronic high-dose beetroot juice supplementation improves time trial performance of well-trained cyclists in normoxia and hypoxia. Nitric Oxide 2019; 85:44-52. [PMID: 30685420 DOI: 10.1016/j.niox.2019.01.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/14/2019] [Accepted: 01/18/2019] [Indexed: 11/21/2022]
Abstract
Dietary nitrate (NO3-) supplementation via beetroot juice (BR) is known to improve endurance performance in untrained and moderately trained individuals. However, conflicting results exist in well-trained individuals. Evidence suggests that the effects of NO3- are augmented during conditions of reduced oxygen availability (e.g., hypoxia), thereby increasing the probability of performance improvements for well-trained athletes in hypoxia vs. normoxia. This randomized, double-blinded, counterbalanced-crossover study examined the effects of 7 days of BR supplementation with 12.4 mmol NO3- per day on 10-km cycling time trial (TT) performance in 12 well-trained cyclists in normoxia (N) and normobaric hypoxia (H). Linear mixed models for repeated measures revealed increases in plasma NO3- and NO2- after supplementation with BR (both p < 0.001). Further, TT performance increased with BR supplementation (∼1.6%, p < 0.05), with no difference between normoxia and hypoxia (p = 0.92). For respiratory variables there were significant effects of supplementation on VO2 (p < 0.05) and VE (p < 0.05) such that average VO2 and VE during the TT increased with BR, with no difference between normoxia and hypoxia (p ≥ 0.86). We found no effect of supplementation on heart rate, oxygen saturation or muscle oxygenation during the TT. Our results provide new evidence that chronic high-dose NO3- supplementation improves cycling performance of well-trained cyclists in both normoxia and hypoxia.
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TILLIN NEALEA, MOUDY SARAH, NOURSE KIRSTYM, TYLER CHRISTOPHERJ. Nitrate Supplement Benefits Contractile Forces in Fatigued but Not Unfatigued Muscle. Med Sci Sports Exerc 2018; 50:2122-2131. [DOI: 10.1249/mss.0000000000001655] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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11
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Christensen PM, Shirai Y, Ritz C, Nordsborg NB. Caffeine and Bicarbonate for Speed. A Meta-Analysis of Legal Supplements Potential for Improving Intense Endurance Exercise Performance. Front Physiol 2017; 8:240. [PMID: 28536531 PMCID: PMC5422435 DOI: 10.3389/fphys.2017.00240] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/05/2017] [Indexed: 12/13/2022] Open
Abstract
A 1% change in average speed is enough to affect medal rankings in intense Olympic endurance events lasting ~45 s to 8 min which for example includes 100 m swimming and 400 m running (~1 min), 1,500 m running and 4000 m track cycling (~4 min) and 2,000 m rowing (~6-8 min). To maximize the likelihood of winning, athletes utilizes legal supplements with or without scientifically documented beneficial effects on performance. Therefore, a continued systematic evidence based evaluation of the possible ergogenic effects is of high importance. A meta-analysis was conducted with a strict focus on closed-end performance tests in humans in the time domain from 45 s to 8 min. These test include time-trials or total work done in a given time. This selection criterion results in a high relevance for athletic performance. Only peer-reviewed placebo controlled studies were included. The often applied and potentially ergogenic supplements beta-alanine, bicarbonate, caffeine and nitrate were selected for analysis. Following a systematic search in Pubmed and SportsDiscuss combined with evaluation of cross references a total of 7 (beta-alanine), 25 (bicarbonate), 9 (caffeine), and 5 (nitrate) studies was included in the meta-analysis. For each study, performance was converted to an average speed (km/h) from which an effect size (ES; Cohens d with 95% confidence intervals) was calculated. A small effect and significant performance improvement relative to placebo was observed for caffeine (ES: 0.41 [0.15–0.68], P = 0.002) and bicarbonate (ES: 0.40 [0.27–0.54], P < 0.001). Trivial and non-significant effects on performance was observed for nitrate (ES: 0.19 [−0.03–0.40], P = 0.09) and beta-alanine (ES: 0.17 [−0.12–0.46], P = 0.24). Thus, caffeine's and bicarbonate's ergogenic effect is clearly documented for intense endurance performance. Importantly, for all supplements an individualized approach may improve the ergogenic effect on performance.
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Affiliation(s)
- Peter M Christensen
- Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of CopenhagenCopenhagen, Denmark.,Team DanmarkCopenhagen, Denmark
| | - Yusuke Shirai
- Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of CopenhagenCopenhagen, Denmark
| | - Christian Ritz
- Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of CopenhagenCopenhagen, Denmark
| | - Nikolai B Nordsborg
- Section of Integrated Physiology, Department of Nutrition, Exercise and Sports, University of CopenhagenCopenhagen, Denmark
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