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Oue A, Iimura Y, Miyakoshi Y, Ota M. Effect of Acute Dietary Nitrate Supplementation on the Changes in Calf Venous Volume during Postural Change and Skeletal Muscle Pump Activity in Healthy Young Adults. Nutrients 2024; 16:1621. [PMID: 38892555 PMCID: PMC11174609 DOI: 10.3390/nu16111621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/22/2024] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
Dietary nitrate (NO3-) supplementation is known to enhance nitric oxide (NO) activity and acts as a vasodilator. In this randomized crossover study, we investigated the effect of inorganic NO3- supplementation on the changes in calf venous volume during postural change and subsequent skeletal muscle pump activity. Fifteen healthy young adults were assigned to receive beetroot juice (BRJ) or a NO3--depleted control beverage (prune juice: CON). Two hours after beverage consumption, the changes in the right calf volume during postural change from supine to upright and a subsequent right tiptoe maneuver were measured using venous occlusion plethysmography. The increase in calf volume from the supine to upright position (total venous volume [VV]) and the decrease in calf volume during the right tiptoe maneuver (venous ejection volume [Ve]) were calculated. Plasma NO3- concentration was higher in the BRJ group than in the CON group 2 h after beverage intake (p < 0.05). However, VV and Ve did not differ between CON and BRJ. These results suggest that acute intake of BRJ may enhance NO activity via the NO3- → nitrite → NO pathway but does not change calf venous pooling due to a postural change or the calf venous return due to skeletal muscle pump activity in healthy young adults.
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Affiliation(s)
- Anna Oue
- Faculty of Health and Sports Sciences, Toyo University, 1-7-11, Akabanedai, Kita-ku, Tokyo 115-8650, Japan; (Y.I.); (Y.M.); (M.O.)
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Wakabayashi H, Sugiyama K, Suzuki S, Sakihama Y, Hashimoto M, Barwood MJ. Influence of acute beetroot juice supplementation on cold-induced vasodilation and fingertip rewarming. Eur J Appl Physiol 2023; 123:495-507. [PMID: 36305974 DOI: 10.1007/s00421-022-05071-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 09/27/2022] [Indexed: 11/29/2022]
Abstract
PURPOSE Vasoactive ingredients in beetroot (BR) such as nitrate are known to induce vasodilation in temperate conditions. This study investigated the effect of BR ingestion on cold induced vasodilation (CIVD) and rewarming of finger skin temperature (Tfing) during and after hand immersion in cold water. METHODS Twenty healthy males (mean ± SD; age 22.2 ± 0.7 years, height 172.6 ± 6.0 cm, body mass 61.3 ± 11.7 kg) repeated a hand cold water immersion test twice with prior BR or water beverage ingestion (randomised order). They rested for 2 h in thermoneutral conditions (27 °C, 40% relative humidity) after consuming the beverage, then immersed their non-dominant hand in 8 °C water for 30 min. They then rewarmed their hand in the ambient air for 20 min. Skin temperature at seven body sites, Tfing, finger skin blood flow (SkBFfing), and blood pressure were measured. RESULTS During hand immersion parameters of CIVD (Tfing and SkBFfing) were not different between BR and water conditions although skin temperature gradient from proximal to distal body sites was significantly smaller with BR (P < 0.05). During rewarming, SkBFfing and cutaneous vascular conductance were significantly higher with BR than with water (P < 0.05). The rewarming speed in Tfing and SkBFfing was significantly faster with BR at 15- (BR 1.24 ± 0.22 vs water 1.11 ± 0.26 °C/min) and 20-min rewarming (P < 0.05). Additionally, individuals with slower rewarming speed with water demonstrated accelerated rewarming with BR supplementation. CONCLUSION BR accelerated rewarming in Tfing and SkBFfing after local cold stimulus, whereas, CIVD response during hand cold immersion was not affected by BR ingestion.
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Affiliation(s)
- Hitoshi Wakabayashi
- Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Sapporo, Japan.
| | - Koji Sugiyama
- Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Sapporo, Japan
| | - Shinichi Suzuki
- Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Sapporo, Japan
| | - Yasuko Sakihama
- Laboratory of Molecular and Ecological Chemistry, Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Makoto Hashimoto
- Laboratory of Molecular and Ecological Chemistry, Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Martin J Barwood
- Faculty of Social and Health Sciences, Leeds Trinity University, Leeds, UK
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Oue A, Iimura Y, Shinagawa A, Miyakoshi Y, Ota M. Effect of Acute Dietary Nitrate Supplementation on the Venous Vascular Response to Static Exercise in Healthy Young Adults. Nutrients 2022; 14:nu14214464. [PMID: 36364727 PMCID: PMC9659063 DOI: 10.3390/nu14214464] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 10/21/2022] [Accepted: 10/21/2022] [Indexed: 11/16/2022] Open
Abstract
The purpose of this study was to test the hypothesis that acute intake of inorganic nitrate (NO3−) via supplementation would attenuate the venoconstriction and pressor response to exercise. Sixteen healthy young adults were assigned in a randomized crossover design to receive beetroot juice (BRJ) or an NO3−-depleted control beverage (prune juice: CON). Two hours after consuming the allocated beverage, participants rested in the supine position. Following the baseline period of 4 min, static handgrip exercise of the left hand was performed at 30% of the maximal voluntary contraction for 2 min. Mean arterial pressure (MAP) and heart rate (HR) were measured. Changes in venous volume in the right forearm and right calf were also measured using venous occlusion plethysmography while cuffs on the upper arm and thigh were inflated constantly to 30−40 mmHg. The plasma NO3− concentration was elevated with BRJ intake (p < 0.05). Exercise increased MAP and HR and decreased venous volume in the forearm and calf, but there were no differences between CON and BRJ. Thus, these findings suggest that acute BRJ intake does not alter the sympathetic venoconstriction in the non-exercising limbs and MAP response to exercise in healthy young adults, despite the enhanced activity of nitric oxide.
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Affiliation(s)
- Anna Oue
- Faculty of Food and Nutritional Sciences, Toyo University, Gunma 374-0193, Japan
- Correspondence: ; Tel.: +81-276-82-9145; Fax: +81-276-82-9033
| | - Yasuhiro Iimura
- Graduate School of Food and Nutritional Sciences, Toyo University, Gunma 374-0193, Japan
| | - Akiho Shinagawa
- Graduate School of Food and Nutritional Sciences, Toyo University, Gunma 374-0193, Japan
| | - Yuichi Miyakoshi
- Faculty of Food and Nutritional Sciences, Toyo University, Gunma 374-0193, Japan
| | - Masako Ota
- Faculty of Food and Nutritional Sciences, Toyo University, Gunma 374-0193, Japan
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Oue A, Iimura Y, Shinagawa A, Miyakoshi Y, Ota M. Acute dietary nitrate supplementation does not change venous volume and compliance in healthy young adults. Am J Physiol Regul Integr Comp Physiol 2022; 323:R331-R339. [PMID: 35816716 DOI: 10.1152/ajpregu.00083.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this randomized single-blind, placebo-controlled, crossover study, we investigated the influence of inorganic nitrate (NO3-) supplementation on venous volume and compliance in the resting forearm and calf. Twenty healthy young adults were assigned to receive an NO3--rich beverage (beetroot juice [BRJ]: 140 mL; ~8 mmol NO3-) or an NO3¯-depleted control beverage (prune juice [CON]: 166 mL; < 0.01 mmol NO3-). Two hours after consuming the allocated beverage, each participant rested in the supine position for 20 min. Cuffs were then placed around the right upper arm and right thigh, inflated to 60 mmHg for 8 min, and then decreased to 0 mmHg at a rate of 1 mmHg/s. During inflation and deflation of cuff pressure, changes in venous volume in the forearm and calf were measured by venous occlusion plethysmography. Venous compliance was calculated as the numerical derivative of the cuff pressure‒venous volume curve in the limbs. The plasma NO3- concentration was elevated by intake of BRJ (before, 15.5 ± 5.8 µM; after, 572.0 ± 116.1 µM, P < 0.05) but not by CON (before, 14.8 ± 7.2 µM; after, 15.3 ± 7.4 µM, P > 0.05). On the other hand, there was no significant difference in venous volume or compliance in the forearm or calf between BRJ and CON. These findings suggest that although acute inorganic NO3- supplementation may enhance the activity of nitric oxide (NO) via NO3- → nitrite → NO pathway, it does not influence venous volume or compliance in the limbs in healthy young adults.
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Affiliation(s)
- Anna Oue
- Faculty of Food and Nutritional Sciences, Toyo University, Gunma, Japan
| | - Yasuhiro Iimura
- Graduate School of Food and Nutritional Sciences, Toyo University, Gunma, Japan
| | - Akiho Shinagawa
- Graduate School of Food and Nutritional Sciences, Toyo University, Gunma, Japan
| | - Yuichi Miyakoshi
- Faculty of Food and Nutritional Sciences, Toyo University, Gunma, Japan
| | - Masako Ota
- Faculty of Food and Nutritional Sciences, Toyo University, Gunma, Japan
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Peel JS, McNarry MA, Heffernan SM, Nevola VR, Kilduff LP, Waldron M. The Effect of Dietary Supplements on Endurance Exercise Performance and Core Temperature in Hot Environments: A Meta-analysis and Meta-regression. Sports Med 2021; 51:2351-2371. [PMID: 34129223 PMCID: PMC8514372 DOI: 10.1007/s40279-021-01500-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND The ergogenic effects of dietary supplements on endurance exercise performance are well-established; however, their efficacy in hot environmental conditions has not been systematically evaluated. OBJECTIVES (1) To meta-analyse studies investigating the effects of selected dietary supplements on endurance performance and core temperature responses in the heat. Supplements were included if they were deemed to: (a) have a strong evidence base for 'directly' improving thermoneutral endurance performance, based on current position statements, or (b) have a proposed mechanism of action that related to modifiable factors associated with thermal balance. (2) To conduct meta-regressions to evaluate the moderating effect of selected variables on endurance performance and core temperature responses in the heat following dietary supplementation. METHODS A search was performed using various databases in May 2020. After screening, 25 peer-reviewed articles were identified for inclusion, across three separate meta-analyses: (1) exercise performance; (2) end core temperature; (3) submaximal core temperature. The moderating effect of several variables were assessed via sub-analysis and meta-regression. RESULTS Overall, dietary supplementation had a trivial significant positive effect on exercise performance (Hedges' g = 0.18, 95% CI 0.007-0.352, P = 0.042), a trivial non-significant positive effect on submaximal core temperature (Hedges' g = 0.18, 95% CI - 0.021 to 0.379, P = 0.080) and a small non-significant positive effect on end core temperature (Hedges' g = 0.20, 95% CI - 0.041 to 0.439, P = 0.104) in the heat. There was a non-significant effect of individual supplements on exercise performance (P = 0.973) and submaximal core temperature (P = 0.599). However, end core temperature was significantly affected by supplement type (P = 0.003), which was attributable to caffeine's large significant positive effect (n = 8; Hedges' g = 0.82, 95% CI 0.433-1.202, P < 0.001) and taurine's medium significant negative effect (n = 1; Hedges' g = - 0.96, 95% CI - 1.855 to - 0.069, P = 0.035). CONCLUSION Supplements such as caffeine and nitrates do not enhance endurance performance in the heat, with caffeine also increasing core temperature responses. Some amino acids might offer the greatest performance benefits in the heat. Exercising in the heat negatively affected the efficacy of many dietary supplements, indicating that further research is needed and current guidelines for performance in hot environments likely require revision.
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Affiliation(s)
- Jennifer S Peel
- A-STEM Centre, College of Engineering, Swansea University, Swansea, UK.
| | - Melitta A McNarry
- A-STEM Centre, College of Engineering, Swansea University, Swansea, UK
| | - Shane M Heffernan
- A-STEM Centre, College of Engineering, Swansea University, Swansea, UK
| | - Venturino R Nevola
- A-STEM Centre, College of Engineering, Swansea University, Swansea, UK
- Defence Science and Technology Laboratory (Dstl), Fareham, Hampshire, UK
| | - Liam P Kilduff
- A-STEM Centre, College of Engineering, Swansea University, Swansea, UK
- Welsh Institute of Performance Science, Swansea University, Swansea, UK
| | - Mark Waldron
- A-STEM Centre, College of Engineering, Swansea University, Swansea, UK
- Welsh Institute of Performance Science, Swansea University, Swansea, UK
- School of Science and Technology, University of New England, Armidale, NSW, Australia
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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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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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Fowler R, Jeffries O, Tallent J, Theis N, Heffernan SM, McNarry MA, Kilduff L, Waldron M. No thermoregulatory or ergogenic effect of dietary nitrate among physically inactive males, exercising above gas exchange threshold in hot and dry conditions. Eur J Sport Sci 2020; 21:370-378. [PMID: 32130090 DOI: 10.1080/17461391.2020.1739144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The aim of this study was to determine the effect of five days dietary nitrate (NO3-) consumption on exercise tolerance and thermoregulation during cycling in hot, dry conditions. In a double-blind, randomised crossover design, 11 healthy males participated in an exercise tolerance test (Tlim) in the heat (35°C, 28% relative humidity), cycling above the thermoneutral gas exchange threshold, after five days of dietary supplementation, with either NO3-rich beetroot juice (BR; ∼ 9.2 mmol NO3-) or placebo (PLA). Changes in plasma [NO3-] and nitrite [NO2-], core and mean skin temperatures, mean local and whole-body sweat rates, heart rate, perceptual ratings and pulmonary gas exchange were measured during exercise, alongside calorimetric estimations of thermal balance. Mean arterial pressures (MAP) were recorded pre-Tlim. There were no differences in Tlim between conditions (BR = 22.8 ± 8.1 min; Placebo = 20.7 ± 7.9 min) (P = 0.184), despite increases in plasma [NO3-] and [NO2-] (P < 0.001) and a 3.8% reduction in resting MAP (P = 0.004) in the BR condition. There were no other differences in thermoregulatory, cardio-metabolic, perceptual or calorimetric responses to the Tlim between conditions (P > 0.05). Dietary NO3- supplementation had no effect on exercise tolerance or thermoregulation in hot, dry conditions, despite reductions in resting MAP and increases in plasma [NO3-] and [NO2-]. Healthy, yet physically inactive individuals with no known impairments in vasodilatory and sudomotor function do not appear to require BR for ergogenic or thermolytic effects during exercise in the heat.
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Affiliation(s)
- Rebecca Fowler
- Faulty of Sport, Health and Applied Sciences, St Mary's University, London, UK
| | - Owen Jeffries
- School of Biomedical, Nutritional and Sport Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Jamie Tallent
- Faulty of Sport, Health and Applied Sciences, St Mary's University, London, UK
| | - Nicola Theis
- School of Sport and Exercise, University of Gloucestershire, Gloucestershire, UK
| | | | | | - Liam Kilduff
- A-STEM, College of Engineering, Swansea University, Swansea, UK.,Welsh Institute of Performance Science, Swansea University, Swansea, UK
| | - Mark Waldron
- A-STEM, College of Engineering, Swansea University, Swansea, UK.,School of Science and Technology, University of New England, Armidale, Australia
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An acute dose of inorganic dietary nitrate does not improve high-intensity, intermittent exercise performance in temperate or hot and humid conditions. Eur J Appl Physiol 2019; 119:723-733. [PMID: 30617465 PMCID: PMC6394696 DOI: 10.1007/s00421-018-04063-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 12/21/2018] [Indexed: 01/13/2023]
Abstract
Purpose Dietary nitrate (NO3−) has repeatedly been shown to improve endurance and intermittent, high-intensity events in temperate conditions. However, the ergogenic effects of dietary NO3− on intermittent exercise performance in hot conditions have yet to be investigated. Methods In a randomised, counterbalanced, double-blind crossover study, 12 recreationally trained males ingested a nitrate-rich beetroot juice shot (BRJ) (6.2 mmol NO3−) or a nitrate-depleted placebo (PLA) (< 0.004 mmol NO3−) 3 h prior to an intermittent sprint test (IST) in temperate (22 °C, 35% RH) and hot conditions (30 °C, 70% RH). The cycle ergometer IST consisted of twenty maximal 6 s sprints interspersed by 114 s of active recovery. Work done, power output, heart rate and RPE were measured throughout; tympanic temperature was measured prior to and upon completion. Results There were no significant effects of supplement on sprint performance in either temperate or hot, humid conditions (p > 0.05). There was a reduced peak (BRJ: 659 ± 100W vs. PLA: 693 ± 139W; p = 0.056) and mean power (BRJ: 543 ± 29W vs. PLA: 575 ± 38W; p = 0.081) following BRJ compared to PLA in the hot and humid condition, but this was not statistically significant. There was no effect of supplement on total work done irrespective of environmental condition. However, ~ 75% of participants experienced performance decreases following BRJ in the hot and humid environment. No differences were observed between trials for tympanic temperature measured at the conclusion of the exercise trial. Conclusion In conclusion, an acute dose of inorganic dietary NO3− does not improve repeated-sprint performance in either temperate, or hot and humid conditions.
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10
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Bock JM, Treichler DP, Norton SL, Ueda K, Hughes WE, Casey DP. Inorganic nitrate supplementation enhances functional capacity and lower-limb microvascular reactivity in patients with peripheral artery disease. Nitric Oxide 2018; 80:45-51. [PMID: 30118808 DOI: 10.1016/j.niox.2018.08.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/07/2018] [Accepted: 08/14/2018] [Indexed: 11/18/2022]
Abstract
Peripheral artery disease (PAD) is characterized by functional and vascular impairments as well as elevated levels of inflammation which are associated with reduced nitric oxide (NO) bioavailability. Inorganic nitrate supplementation boosts NO bioavailability potentially improving functional and vasodilatory capacities and may reduce inflammation. Twenty-one patients with PAD were randomly assigned to sodium nitrate (NaNO3) or placebo supplementation groups for eight-weeks. Outcome measures included a 6-min walk test (6 MWT), blood flow and vasodilator function in the forearm and calf, as well as plasma inflammatory and adhesion biomarker concentrations. NaNO3 elevated plasma nitrate (32.3 ± 20.0 to 379.8 ± 204.6 μM) and nitrite (192.2 ± 51.8 to 353.1 ± 134.2 nM), improved 6 MWT performance (387 ± 90 to 425 ± 82 m), peak calf blood flow (BFPeak; 11.6 ± 4.9 to 14.1 ± 5.1 mL/dL tissue/min), and peak calf vascular conductance (VCPeak; 11.1 ± 4.3 to 14.2 ± 4.9 mL/dL tissue/min/mmHg) (p < 0.05 for all). Improvements in calf BFPeak (r = 0.70, p < 0.05) and VCPeak (r = 0.61, p < 0.05) correlated with changes in 6 MWT distance. Placebo supplementation did not change plasma nitrate or nitrite, 6 MWT, calf BFPeak, or calf VCPeak. Forearm vascular function nor inflammatory and adhesion biomarker concentrations changed in either group. Eight-weeks of NaNO3 supplementation improves vasodilatory capacity in the lower-limbs of patients with PAD, which correlated with improvement in functional capacity.
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Affiliation(s)
- Joshua M Bock
- Department of Physical Therapy and Rehabilitation Science, USA.
| | | | - Samuel L Norton
- Department of Physical Therapy and Rehabilitation Science, USA.
| | - Kenichi Ueda
- Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
| | | | - Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, USA; Abboud Cardiovascular Research Center, USA; Fraternal Order of Eagles Diabetes Research Center, USA.
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11
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Fan JL, Bourdillon N, Meyer P, Kayser B. Oral Nitrate Supplementation Differentially Modulates Cerebral Artery Blood Velocity and Prefrontal Tissue Oxygenation During 15 km Time-Trial Cycling in Normoxia but Not in Hypoxia. Front Physiol 2018; 9:869. [PMID: 30061839 PMCID: PMC6054990 DOI: 10.3389/fphys.2018.00869] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/18/2018] [Indexed: 12/22/2022] Open
Abstract
Background: Nitrate is a precursor of nitric oxide (NO), an important regulator of cerebral perfusion in normoxic and hypoxic conditions. Nitrate supplementation could be used to improve cerebral perfusion and oxygenation during exercise in hypoxia. The effects of dietary nitrate supplementation on cerebral haemodynamics during exercise in severe hypoxia (arterial O2 saturation < 70%) have not been explored. Methods: In twelve trained male cyclists, we measured blood pressure (BP), middle cerebral artery blood velocity (MCAv), cerebrovascular resistance (CVR) and prefrontal oxyhaemoglobin and deoxyhaemoglobin concentration (O2Hb and HHb, respectively) during 15 km cycling time trials (TT) in normoxia and severe hypoxia (11% inspired O2, peripheral O2 saturation ∼66%) following 3-day oral supplementation with placebo or sodium nitrate (0.1 mmol/kg/day) in a randomised, double-blinded manner. We tested the hypothesis that dietary nitrate supplementation increases MCAv and cerebral O2Hb during TT in severe hypoxia. Results: During TT in normoxia, nitrate supplementation lowered MCAv by ∼2.3 cm/s and increased cerebral O2Hb by ∼6.8 μM and HHb by ∼2.1 μM compared to normoxia placebo (p ≤ 0.01 for all), while BP tended to be lowered (p = 0.06). During TT in severe hypoxia, nitrate supplementation elevated MCAv (by ∼2.5 cm/s) and BP (by ∼5 mmHg) compared to hypoxia placebo (p < 0.01 for both), while it had no effect on cerebral O2Hb (p = 0.98), HHb (p = 0.07) or PETCO2 (p = 0.12). Dietary nitrate had no effect of CVR during TT in normoxia or hypoxia (p = 0.19). Conclusion: Our findings indicate that during normoxic TT, the modulatory effect of dietary nitrate on regional and global cerebral perfusion is heterogeneous. Meanwhile, the lack of major changes in cerebral perfusion with dietary nitrate during hypoxic TT alludes to an exhausted cerebrovascular reserve.
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Affiliation(s)
- Jui-Lin Fan
- Wellington Medical Technology Group, Department of Surgery and Anaesthesia, University of Otago, Wellington, New Zealand.,Centre for Translational Physiology, University of Otago, Wellington, New Zealand
| | - Nicolas Bourdillon
- Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland
| | - Philippe Meyer
- Cardiology Service, Geneva University Hospital, Geneva, Switzerland
| | - Bengt Kayser
- Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland
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