Commentaries on Viewpoint: Can elite athletes benefit from dietary nitrate supplementation?
2015; American Physiological Society; Volume: 119; Issue: 6 Linguagem: Inglês
10.1152/japplphysiol.00640.2015
ISSN8750-7587
AutoresMichael Hultström, Cristiane Amorim de Paula, Marco Antônio Peliky Fontes, Simone Porcelli, G. Bellistri, Lorenzo Pugliese, Letizia Rasica, Mauro Marzorati, Gaspare Pavei, Scott K. Ferguson, Clark T. Holdsworth, Timothy I. Musch, David C. Poole, Nicolas Bourdillon, Matthew W. Hoon, Louise M. Burke, D. W. Michielli, Raphaël Faiss, Grégoire P. Millet, Benjamin T. Corona, Michael S. Green, Anderson Luiz Bezerra da Silveira, Amy L. Sindler, Darren P. Casey, Bruce D. Johnson, Courtney M. Wheatley, Amanda Carlson‐Phillips, Laura J. Kunces, Raúl Bescós, L C Johnson, Christopher R. Martens, Jamie N. Justice, Sam B. Ballak, Dov B. Ballak, Samuel Penna Wanner, Cândido Celso Coimbra, Shabina Rehman,
Tópico(s)Heart Rate Variability and Autonomic Control
ResumoPerspectivesCommentaries on Viewpoint: Can elite athletes benefit from dietary nitrate supplementation?Published Online:15 Sep 2015https://doi.org/10.1152/japplphysiol.00640.2015MoreSectionsPDF (82 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Michael Hultström.Author AffiliationsDepartment of Medical Cell Biology and Department of Surgical Sciences Uppsala University.LACK OF EFFECT OF DIETARY NITRATE IN ELITE ATHLETES MAY BE DUE TO DILATION OF NON-PRIORITIZED VASCULAR BEDSto the editor: As Jonvik and colleagues (3) describe, dietary nitrate appears to improve the performance of well-trained athletes, whereas all studies in professional elite athletes have shown no effect or even a detrimental effect. One explanation they do not touch upon is the fact that nitrate-derived nitric oxide production is not site specific and thus causes vasodilation of other vascular beds, which could impair blood flow to prioritized muscles during maximal exertion. In maximal, whole body exercise there is evidence that blood flow can be reduced to other muscle groups to maintain total conductance within the limit of maximal cardiac output (2). Elite athletes are probably more prone to working close to this limit. In addition, nitric oxide production from nitrate seems to be enhanced by hypoxia (4), and non-prioritized muscles and other organs would tend to be more hypoxic during maximal exertion. Nitrate-derived nitric oxide could thereby target these vascular beds specifically, which is supported by recent data showing that nitrate supplementation impairs the generalized vasoconstriction of the diving reflex (5) and has no effect during high-altitude running (1). Thus nitrate-mediated vasodilation could reduce oxygen delivery to critical muscles in elite athletes working very close to their maximal cardiac output by dilating non-prioritized vascular beds.REFERENCES1. Arnold JT, Oliver SJ, Lewis-Jones TM, Wylie LJ, Macdonald JH. Beetroot juice does not enhance altitude running performance in well-trained athletes. Appl Physiol Nutr Metab 1–6, 2015.ISI | Google Scholar2. Calbet JA, Gonzalez-Alonso J, Helge JW, Sondergaard H, Munch-Andersen T, Boushel R, Saltin B. Cardiac output and leg and arm blood flow during incremental exercise to exhaustion on the cycle ergometer. J Appl Physiol (1985) 103: 969–978, 2007.Link | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJ, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol (1985); doi:10.1152/japplphysiol.00232.2015Link | ISI | Google Scholar4. Kapil V, Weitzberg E, Lundberg JO, Ahluwalia A. Clinical evidence demonstrating the utility of inorganic nitrate in cardiovascular health. Nitric Oxide 38: 45–57, 2014.Crossref | PubMed | ISI | Google Scholar5. Schiffer TA, Larsen FJ, Lundberg JO, Weitzberg E, Lindholm P. Effects of dietary inorganic nitrate on static and dynamic breath-holding in humans. Respir Physiol Neurobiol 185: 339–348, 2013.Crossref | ISI | Google ScholarREFERENCES1. Arnold JT, Oliver SJ, Lewis-Jones TM, Wylie LJ, Macdonald JH. Beetroot juice does not enhance altitude running performance in well-trained athletes. Appl Physiol Nutr Metab 1–6, 2015.ISI | Google Scholar2. Calbet JA, Gonzalez-Alonso J, Helge JW, Sondergaard H, Munch-Andersen T, Boushel R, Saltin B. Cardiac output and leg and arm blood flow during incremental exercise to exhaustion on the cycle ergometer. J Appl Physiol (1985) 103: 969–978, 2007.Link | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJ, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol (1985); doi:10.1152/japplphysiol.00232.2015Link | ISI | Google Scholar4. Kapil V, Weitzberg E, Lundberg JO, Ahluwalia A. Clinical evidence demonstrating the utility of inorganic nitrate in cardiovascular health. Nitric Oxide 38: 45–57, 2014.Crossref | PubMed | ISI | Google Scholar5. Schiffer TA, Larsen FJ, Lundberg JO, Weitzberg E, Lindholm P. Effects of dietary inorganic nitrate on static and dynamic breath-holding in humans. Respir Physiol Neurobiol 185: 339–348, 2013.Crossref | ISI | Google ScholarCristiane Amorim de Paula and Marco Antônio Peliky Fontes.Author AffiliationsDepartment of Physiology & Biophysics, Federal University of Minas Gerais, Brazil.THE MINIMUM BENEFIT OF DIETARY NITRATE SUPPLEMENTATION IN ELITE VS. RECREATIONAL ATHLETES: A TOPIC OF DEBATE?to the editor: The article by Jonvik and colleagues (1) raises the question of whether elite athletes are benefited by ergogenic properties of nitrate supplementation compared with recreational athletes. In the conclusion, authors state that “recent data tend to suggest that the ergogenic properties of nitrate supplementation are restricted to the recreational athlete and not evident in highly trained, elite athlete.” Nitric oxide (NO) production increases in response to physical activity, a requirement to maintain homeostasis during exercise (4). Therefore, ergogenic supplements that favors NO formation and cell metabolism (2) will certainly favor endurance in individuals whose NO bioavailability is lower. Notoriously (but not necessarily restrict to), recreational athletes as well as sedentary individuals will have a greater benefit of nitrate supplementation. Besides, the comparison between kayakers, cross-country skiers, cyclists, and 1,500-m runners is absolutely complex. The mechanical demands for these different modalities are totally different and the synergistic actions between NO and other vasoactive factors, including endothelin, EDHF, prostacyclin, angiotensins, bradykinin, and others must be taken in consideration for each region on demand. Even if we suppose that V̇o2max was compared and assumed to be equivalent between individuals of these different groups, the localized vascular reactivity differs for different modalities of exercise (3, 5) and the contribution of NO for each specific condition is unknown. In conclusion, to be considered a topic of debate, the question raised by Jonvik and colleagues requires extensive additional knowledge from integrative physiology and more homogeneous group approach.REFERENCES1. Jonvik KL, Nyakayiru J, van Loon LJ, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol (1985); doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar2. Larsen FJ, Schiffer TA, Borniquel S, Sahlin K, Ekblom B, Lundberg JO, Weitzberg E. Dietary inorganic nitrate improves mitochondrial efficiency in humans. Cell Metab 13: 149–159, 2011.Crossref | PubMed | ISI | Google Scholar3. Rowley NJ, Dawson EA, Birk GK, Cable NT, George K, Whyte G, Thijssen DH, Green DJ. Exercise and arterial adaptation in humans: uncoupling localized and systemic effects. J Appl Physiol (1985) 110: 1190–1195, 2011.Link | ISI | Google Scholar4. Stamler JS, Meissner G. Physiology of nitric oxide in skeletal muscle. Physiol Rev 81: 209–237, 2001.Link | ISI | Google Scholar5. Thijssen DH, Dawson EA, Black MA, Hopman MT, Cable NT, Green DJ. Brachial artery blood flow responses to different modalities of lower limb exercise. Med Sci Sports Exerc 41: 1072–1079, 2009.Crossref | PubMed | ISI | Google ScholarREFERENCES1. Jonvik KL, Nyakayiru J, van Loon LJ, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol (1985); doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar2. Larsen FJ, Schiffer TA, Borniquel S, Sahlin K, Ekblom B, Lundberg JO, Weitzberg E. Dietary inorganic nitrate improves mitochondrial efficiency in humans. Cell Metab 13: 149–159, 2011.Crossref | PubMed | ISI | Google Scholar3. Rowley NJ, Dawson EA, Birk GK, Cable NT, George K, Whyte G, Thijssen DH, Green DJ. Exercise and arterial adaptation in humans: uncoupling localized and systemic effects. J Appl Physiol (1985) 110: 1190–1195, 2011.Link | ISI | Google Scholar4. Stamler JS, Meissner G. Physiology of nitric oxide in skeletal muscle. Physiol Rev 81: 209–237, 2001.Link | ISI | Google Scholar5. Thijssen DH, Dawson EA, Black MA, Hopman MT, Cable NT, Green DJ. Brachial artery blood flow responses to different modalities of lower limb exercise. Med Sci Sports Exerc 41: 1072–1079, 2009.Crossref | PubMed | ISI | Google ScholarSimone Porcelli1, Giuseppe Bellistri12, Lorenzo Pugliese1, Letizia Rasica1, Mauro Marzorati1, and Gaspare Pavei3.Author Affiliations1Institute of Molecular Bioimaging & PhysiologyNational Research Council, Italy .2Department of Biomedical Sciences for HealthUniversity of Milan, Italy .3Dept of Pathophysiology & TransplantationUniversity of Milan, Italy.COMMENTARY ON “CAN ELITE ATHLETES BENEFIT FROM DIETARY NITRATE SUPPLEMENTATION?”to the editor: Jonvik and colleagues (3) have raised a really interesting and burning question about the ergogenic benefits of nitrate supplementation in elite athletes. In our previous experiments (4) we have seen that the effects of nitrate supplementation on oxygen consumption and running performance are significantly related to the individual aerobic fitness level, with no benefits observed on highly trained subjects (V̇o2max >60 ml·kg−1·min−1). Thus our results seem to suggest that nitrate supplementation may be ineffective in elite athletes. However, “responders” are present among elite athletes (1–2, 5) and the potential effects of nitrate supplementation on these subjects are unclear and need further examination. As indicated by a significant negative correlation between the increase of plasma nitrite after supplementation and performance in our results, the magnitude of the variance in nitrate/nitrite concentration after supplementation may be a crucial point. In accordance, a greater increase in nitrite levels after supplementation has been observed in “responders” (5). Thus, in our opinion, more attention should be paid to the effects of nitrate supplementation on nitrate/nitrite levels than on the aerobic fitness of the subject itself, although these two aspects are related. Future studies need to investigate in elite athletes the “dose-response” relationship between nitrate supplementation and the amount of change in blood concentration of nitrate/nitrite to clarify if elite athletes may request a higher dose of nitrate or a longer supplementation period to improve their performance.REFERENCES1. Boorsma RK, Whitfield J, Spriet LL. Beetroot juice supplementation does not improve performance of elite 1500-m runners. Med Sci Sports Exerc 46: 2326–2334, 2014.Crossref | ISI | Google Scholar2. Christensen PM, Nyberg M, Bangsbo J. Influence of nitrate supplementation on V̇o2, kinetics and endurance of elite cyclists. Scand J Med Sci Sports 23: e21–e31, 2013.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. Porcelli S, Ramaglia M, Bellistri G, Pavei G, Pugliese L, Montorsi M, Rasica L, Marzorati M. Aerobic fitness affects the exercise performance responses to nitrate supplementation. Med Sci Sports Exerc 47: 1643–1651, 2015.Crossref | PubMed | ISI | Google Scholar5. Wilkerson DP, Hayward GM, Bailey SJ, Vanhatalo A, Blackwell JR, Jones AM. Influence of acute dietary nitrate supplementation on 50 mile time trial performance in well-trained cyclists. Eur J Appl Physiol 112: 4127–4134, 2012.Crossref | PubMed | ISI | Google ScholarREFERENCES1. Boorsma RK, Whitfield J, Spriet LL. Beetroot juice supplementation does not improve performance of elite 1500-m runners. Med Sci Sports Exerc 46: 2326–2334, 2014.Crossref | ISI | Google Scholar2. Christensen PM, Nyberg M, Bangsbo J. Influence of nitrate supplementation on V̇o2, kinetics and endurance of elite cyclists. Scand J Med Sci Sports 23: e21–e31, 2013.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. Porcelli S, Ramaglia M, Bellistri G, Pavei G, Pugliese L, Montorsi M, Rasica L, Marzorati M. Aerobic fitness affects the exercise performance responses to nitrate supplementation. Med Sci Sports Exerc 47: 1643–1651, 2015.Crossref | PubMed | ISI | Google Scholar5. Wilkerson DP, Hayward GM, Bailey SJ, Vanhatalo A, Blackwell JR, Jones AM. Influence of acute dietary nitrate supplementation on 50 mile time trial performance in well-trained cyclists. Eur J Appl Physiol 112: 4127–4134, 2012.Crossref | PubMed | ISI | Google ScholarScott K. Ferguson, Clark T. Holdsworth, Timothy I. Musch, and David C. Poole.Author AffiliationsDepartment of Anatomy and Physiology Department of Kinesiology Kansas State University.ELITE ATHLETES CAN BENEFIT FROM DIETARY NITRATE SUPPLEMENTATIONto the editor: The Viewpoint article published in the Journal of Applied Physiology by Jonvik et al. (3) raised pertinent questions regarding nitrate supplementation. A crucial consideration that was absent from that Viewpoint concerns the dependence of the degree of benefit(s) on the event and environment in which the athlete performs/competes. As highlighted by Jonvik et al. (3), there is considerable evidence to support beneficial impacts of nitrate supplementation on the physiological function of type II, but not type I, muscle fibers. Our laboratory has demonstrated that nitrate supplementation via beetroot juice preferentially elevates blood flow and the microvascular PO2 (pressure required for blood-myocyte O2 flux) within fast twitch muscles. This effect is likely dependent upon the lower PO2 environment within these tissues (4), which facilitates reduction of nitrite to nitric oxide. This effect may underlie the improved V̇o2 kinetics and tolerance to exercise evident during severe-intensity exercise transitions as well as the improved performance at simulated altitude observed in humans (1, 5). In this regard, athletes competing in events held at altitude, particularly those with frequent transitions in work rate, for example, runners of the Ultra-Trail Du Mont Blanc, a trail run of ∼170 km with ∼10,000 m of positive elevation change, or other elite mountain athletes (e.g., climbers or cyclists) may potentially see improvements in performance. Considering further the increase in contractile function of type II muscle reported by Hernandez et al. (2) after nitrate supplementation it seems logical that elite power athletes (power-lifters) may also potentially benefit from nitrate supplementation.REFERENCES1. Breese BC, McNarry MA, Marwood S, Blackwell JR, Bailey SJ, Jones AM. Beetroot juice supplementation speeds O2 uptake kinetics and improves exercise tolerance during severe-intensity exercise initiated from an elevated metabolic rate. Am J Physiol Regul Integr Comp Physiol 305: R1441–R1450, 2013.Link | ISI | Google Scholar2. Hernandez A, Schiffer TA, Ivarsson N, Cheng AJ, Bruton JD, Lundberg JO, Weitzberg E, Westerblad H. Dietary nitrate increases tetanic [Ca2+]i and contractile force in mouse fast-twitch muscle. J Physiol 590: 3575–3583, 2012.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJ, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. McDonough P, Behnke BJ, Padilla DJ, Musch TI, Poole DC. Control of microvascular oxygen pressures in rat muscles comprised of different fibre types. J Physiol 563: 903–913, 2005.Crossref | PubMed | ISI | Google Scholar5. Vanhatalo A, Fulford J, Bailey SJ, Blackwell JR, Winyard PG, Jones AM. Dietary nitrate reduces muscle metabolic perturbation and improves exercise tolerance in hypoxia. J Physiol 589: 5517–5528, 2011.Crossref | PubMed | ISI | Google ScholarREFERENCES1. Breese BC, McNarry MA, Marwood S, Blackwell JR, Bailey SJ, Jones AM. Beetroot juice supplementation speeds O2 uptake kinetics and improves exercise tolerance during severe-intensity exercise initiated from an elevated metabolic rate. Am J Physiol Regul Integr Comp Physiol 305: R1441–R1450, 2013.Link | ISI | Google Scholar2. Hernandez A, Schiffer TA, Ivarsson N, Cheng AJ, Bruton JD, Lundberg JO, Weitzberg E, Westerblad H. Dietary nitrate increases tetanic [Ca2+]i and contractile force in mouse fast-twitch muscle. J Physiol 590: 3575–3583, 2012.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJ, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. McDonough P, Behnke BJ, Padilla DJ, Musch TI, Poole DC. Control of microvascular oxygen pressures in rat muscles comprised of different fibre types. J Physiol 563: 903–913, 2005.Crossref | PubMed | ISI | Google Scholar5. Vanhatalo A, Fulford J, Bailey SJ, Blackwell JR, Winyard PG, Jones AM. Dietary nitrate reduces muscle metabolic perturbation and improves exercise tolerance in hypoxia. J Physiol 589: 5517–5528, 2011.Crossref | PubMed | ISI | Google ScholarNicolas Bourdillon.Author AffiliationsISSUL, Université de Lausanne.VIEWPOINT: BENEFITS FROM NITRATE SUPPLEMENTATION IN HYPOXIA?to the editor: Jonvik et al. (3) do not discuss potential benefits of nitrate supplementation in subjects exposed to hypoxia, when O2 supply limits O2 uptake and an O2 sparing effect of NO (4) could potentially improve performance. In hypoxia, increased NO levels are associated with decreased risk for altitude illness and potentially with increased performance (2, 4). Nitrate, by elevating NO bioavailability, might improve performance in three ways: 1) hypoxic pulmonary vasoconstriction might be mitigated, improving right heart function and thereby exercise performance (5); 2) cerebral blood flow and cerebral tissue oxygenation might be improved, potentially increasing motor drive; and 3) by oxygen sparing, NO might allow more aerobic power for a given oxygen consumption (4). Arnold et al. (1) found that nitrate supplementation did not consistently enhance running performance of well-trained athletes in hypoxia during incremental (at 4,000 m) and 10-km time trial (at 2,500 m) exercises. They did not look at hypoxic pulmonary arterial vasoconstriction, and the acute hypoxic exposure they used may have preceded full hypoxic pulmonary artery vasoconstriction. Nevertheless, as discussed by Jonvik et al. (3), perhaps only less trained athletes positively respond to nitrate supplementation (1, 3). Future studies should focus on identifying the factors that could explain why some athletes are more responsive to nitrate supplementation than others. For athletes competing at altitude this should be done in hypoxia too. So far there is no evidence for systematic nitrate supplementation for prevention of hypoxia-induced pulmonary hypertension and for improving exercise performance in hypoxia in trained athletes.REFERENCES1. Arnold JT, Oliver SJ, Lewis-Jones TM, Wylie LJ, Macdonald JH. Beetroot juice does not enhance altitude running performance in well-trained athletes. Appl Physiol Nutr Metab Physiol 40: 590–595, 2015.Crossref | PubMed | ISI | Google Scholar2. Beall CM, Laskowski D, Erzurum SC. Nitric oxide in adaptation to altitude. Free Radic Biol Med 52: 1123–1134, 2012.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol Oxf Engl 191: 59–66, 2007.Crossref | PubMed | ISI | Google Scholar5. Naeije R, Huez S, Lamotte M, Retailleau K, Neupane S, Abramowicz D, Faoro V. Pulmonary artery pressure limits exercise capacity at high altitude. Eur Respir J 36: 1049–1055, 2010.Crossref | ISI | Google ScholarREFERENCES1. Arnold JT, Oliver SJ, Lewis-Jones TM, Wylie LJ, Macdonald JH. Beetroot juice does not enhance altitude running performance in well-trained athletes. Appl Physiol Nutr Metab Physiol 40: 590–595, 2015.Crossref | PubMed | ISI | Google Scholar2. Beall CM, Laskowski D, Erzurum SC. Nitric oxide in adaptation to altitude. Free Radic Biol Med 52: 1123–1134, 2012.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. Larsen FJ, Weitzberg E, Lundberg JO, Ekblom B. Effects of dietary nitrate on oxygen cost during exercise. Acta Physiol Oxf Engl 191: 59–66, 2007.Crossref | PubMed | ISI | Google Scholar5. Naeije R, Huez S, Lamotte M, Retailleau K, Neupane S, Abramowicz D, Faoro V. Pulmonary artery pressure limits exercise capacity at high altitude. Eur Respir J 36: 1049–1055, 2010.Crossref | ISI | Google ScholarMatthew W. Hoon.Author AffiliationsSchool of Exercise Science Australian Catholic University.Louise M. Burke.Author AffiliationsSports Nutrition Australian Institute of Sport Mary MacKillop Institute for Health Research Australian Catholic University.NITRATE SUPPLEMENTATION: SOME ELITE ATHLETES MAY BENEFIT AND HARM IS UNLIKELYto the editor: The Viewpoint of Jovnik and colleagues (3) provides insight into why nitrate (NO3−) supplementation may have fewer benefits for elite athletes and why studies in highly trained populations have reported mixed outcomes. Based on currently available literature, it is reasonable to conclude NO3− is more effective in improving performance in lower caliber or lesser-trained athletes. However, given that “responders” are still apparent in studies involving elite cohorts and few side effects other than pink urine/stools after beetroot juice ingestion have been reported, NO3− consumption may still be a useful nutritional strategy for high-caliber athletes.The efficacy of NO3− supplementation is likely associated with the specific conditions of exercise. Shorter, high-intensity events may benefit more because of hypoxic and acidic stimulation of the NO3−NO2−NO reduction pathway and the relatively greater involvement of type II fiber (2). In particular, the exaggeration of these conditions in smaller muscle groups would appear to favor upper body-dominant exercise (2), possibly explaining observations of benefits to competitive athletes in kayaking and rowing (1, 4).Another potential application of NO3− supplementation is to attenuate the ergolytic effects of hypoxia (5). This may be useful to athletes undertaking altitude training or competing in high-altitude environments (e.g., cross-country skiers, mountainous cycling stages) where O2 availability is challenged. Research to verify this effect in elite subjects is required.Therefore, although NO3− supplementation is more valuable to lesser trained or lower caliber athletes, there are perhaps certain sports, events, and conditions where it may assist elite competitors.REFERENCES1. Hoon MW, Jones AM, Johnson NA, Blackwell JR, Broad EM, Lundy B, Rice AJ, Burke LM. The effect of variable doses of inorganic nitrate-rich beetroot juice on simulated 2,000-m rowing performance in trained athletes. Int J Sports Physiol Perform 9: 615–620, 2014.Crossref | ISI | Google Scholar2. Jones AM. Dietary nitrate supplementation and exercise performance. Sports Med 44: 35–45, 2014.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. Peeling P, Cox GR, Bullock N, Burke LM. Beetroot juice improves on-water 500 m time-trial performance, and laboratory-based paddling economy in national and international-level kayak athletes. Int J Sport Nutr Exerc Metab, in press.ISI | Google Scholar5. Vanhatalo A, Fulford J, Bailey SJ, Blackwell JR, Winyard PG, Jones AM. Dietary nitrate reduces muscle metabolic perturbation and improves exercise tolerance in hypoxia. J Physiol 589: 5517–5528, 2011.Crossref | PubMed | ISI | Google ScholarREFERENCES1. Hoon MW, Jones AM, Johnson NA, Blackwell JR, Broad EM, Lundy B, Rice AJ, Burke LM. The effect of variable doses of inorganic nitrate-rich beetroot juice on simulated 2,000-m rowing performance in trained athletes. Int J Sports Physiol Perform 9: 615–620, 2014.Crossref | ISI | Google Scholar2. Jones AM. Dietary nitrate supplementation and exercise performance. Sports Med 44: 35–45, 2014.Crossref | PubMed | ISI | Google Scholar3. Jonvik KL, Nyakayiru J, van Loon LJC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar4. Peeling P, Cox GR, Bullock N, Burke LM. Beetroot juice improves on-water 500 m time-trial performance, and laboratory-based paddling economy in national and international-level kayak athletes. Int J Sport Nutr Exerc Metab, in press.ISI | Google Scholar5. Vanhatalo A, Fulford J, Bailey SJ, Blackwell JR, Winyard PG, Jones AM. Dietary nitrate reduces muscle metabolic perturbation and improves exercise tolerance in hypoxia. J Physiol 589: 5517–5528, 2011.Crossref | PubMed | ISI | Google ScholarDonald W. Michielli.Author AffiliationsDepartment of Kinesiology Brooklyn College of the City University of New York.COMMENT ON “CAN ELITE ATHLETES BENEFIT FROM DIETARY NITRATE SUPPLEMENTATION?”to the editor: The authors (2) addressed an interesting question, “Can elite athletes benefit from dietary nitrate supplementation?” In their discussion, the authors point out that a positive response could make the difference that determines if a new world record is set. However, a negative response could also be helpful in guiding coaches and athletes in their training regimes. Legitimate questions deserve legitimate answers that can only be gained through carefully planned research.All exercise training programs should be guided by scientific principles that include intensity, frequency, duration, and specificity of exercise. The authors mentioned but did not elaborate on the importance of the specificity of exercise testing. The effects of exercise training and/or a supplement on exercise performance can only be answered if the mode of exercise testing is the same as the training mode. The energy systems, muscle group recruitment, and the biomechanics vary according to the specific demands of the mode of exercise. Nitrate (NO3−) supplementation has been used to enhance exercise performance with limited success in elite athletes (1, 3, 4, 5). When cross-country skiers were tested on a treadmill after nitrate supplementation, no significant differences were observed in running performance (3, 5). After NO3− supplementation, kayakers tested on a laboratory kayak ergometer or in the water, significant improvements in time trials were noted (4). However, NO3− ingestion did not affect power output in elite cyclists when tested in the same mode (1). Therefore, more research is needed that incorporates the specificity principle to resolve the question (2).REFERENCES1. Christensen PM, Nyberg M, Bangsbo J. Influence of nitrate supplementation on VO2 kinetics and endurance of elite cyclists. Scand J Med Sci Sports 23: e21–31, 2013.Crossref | PubMed | ISI | Google Scholar2. Jonvik KL, Nyakayiru J, van Loon Luc JC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar3. Peacock O, Tjonna AE, James P, Wisloff U, Welde B, Bohlke N, Smith A, Stokes K, Cook C, Sanbaak O. Dietary nitrate does not enhance running performances in elite cross-country skiers. Med Sci Sports Exerc 44: 2213–2219, 2012.Crossref | PubMed | ISI | Google Scholar4. Peeling P, Cox GR, Bullock N, Burke LM. Beetroot juice improves on-water 500 m time-trial performance, and laboratory-based paddling economy in national and international-level kayak athletes. Int J Sport Nutr Exerc Metab, in press.ISI | Google Scholar5. Sandbaak SB, Sandbaak O, Peacock O, James P, Welde B, Stokes K, Bohlke N, Tjonna AE. Effects of acute supplementation of l-arginine and nitrate on endurance and sprint performance in elite athletes. Nitric Oxide 48: 10–15, 2015.Crossref | ISI | Google ScholarREFERENCES1. Christensen PM, Nyberg M, Bangsbo J. Influence of nitrate supplementation on VO2 kinetics and endurance of elite cyclists. Scand J Med Sci Sports 23: e21–31, 2013.Crossref | PubMed | ISI | Google Scholar2. Jonvik KL, Nyakayiru J, van Loon Luc JC, Verdijk LB. Viewpoint: Can elite athletes benefit from dietary nitrate supplementation? J Appl Physiol; doi:10.1152/japplphysiol.00232.2015.Link | ISI | Google Scholar3. Peacock O, Tjonna AE, James P, Wisloff U, Welde B, Bohlke N, Smith A, Stokes K, Cook C, Sanbaak O. Dietary nitrate does not enhance running performances in elite cross-country skiers. Med Sci Sports Exerc 44: 2213–2219, 2012.Crossref | PubMed | ISI | Google Scholar4. Peeling P, Cox GR, Bullock N, Burke LM. Beetroot juice improves on-water 500 m time-trial performance, and laboratory-based paddling economy in national and international-level kayak athletes. Int J Sport Nutr Exerc Metab, in press.ISI | Google Scholar5. Sandbaak SB, Sandbaak O, Peacock O, James P, Welde B, Stokes K, Bohlke N, Tjonna AE. Effects of acute supplementation of l-arginine and nitrate on endurance and sprint performance in elite athletes. Nitric Oxide 48: 10–15, 2015.Crossref | ISI | Google ScholarRaphael Faiss.Author AffiliationsSwiss Federal Institute of Sport Magglingen, Switzerland.Grégoire P. Millet.Author AffiliationsISSUL Institute of Sport Sciences Universit
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