Publications by year
In Press
McDonagh STJ, Wylie LJ, Morgan P, Vanhatalo A, Jones A (In Press). A randomised controlled trial exploring the effects of different beverages consumed alongside a nitrate-rich meal on systemic blood pressure. Nutrition and Health
Jones AM, Vanhatalo AT, Doust JH (In Press). Aerobic exercise performance. In Eston R, Reilly T (Eds.) Kinanthropometry and exercise physiology laboratory manual: Tests, procedures and data. Volume 2: Exercise physiology, London and New York: Routledge, 271-306.
Bailey SJ, Vanhatalo A, Black MI, DiMenna FJ, Jones AM (In Press). Effects of priming and pacing strategy on VO2 kinetics and cycling performance.
Vanhatalo A, Jones AM (In Press). Influence of creatine supplementation on the all-out critical power test. Journal of Exercise Science and Fitness
2023
Kadach S, Park JW, Stoyanov Z, Black MI, Vanhatalo A, Burnley M, Walter PJ, Cai H, Schechter AN, Piknova B, et al (2023). 15 N-labeled dietary nitrate supplementation increases human skeletal muscle nitrate concentration and improves muscle torque production.
Acta Physiol (Oxf),
237(3).
Abstract:
15 N-labeled dietary nitrate supplementation increases human skeletal muscle nitrate concentration and improves muscle torque production.
AIM: Dietary nitrate (NO3 - ) supplementation increases nitric oxide bioavailability and can enhance exercise performance. We investigated the distribution and metabolic fate of ingested NO3 - at rest and during exercise with a focus on skeletal muscle. METHODS: in a randomized, crossover study, 10 healthy volunteers consumed 12.8 mmol 15 N-labeled potassium nitrate (K15 NO3 ; NIT) or potassium chloride placebo (PLA). Muscle biopsies were taken at baseline, at 1- and 3-h post-supplement ingestion, and immediately following the completion of 60 maximal intermittent contractions of the knee extensors. Muscle, plasma, saliva, and urine samples were analyzed using chemiluminescence to determine absolute [NO3 - ] and [NO2 - ], and by mass spectrometry to determine the proportion of NO3 - and NO2 - that was 15 N-labeled. RESULTS: Neither muscle [NO3 - ] nor [NO2 - ] were altered by PLA. Following NIT, muscle [NO3 - ] (but not [NO2 - ]) was elevated at 1-h (from ~35 to 147 nmol/g, p
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Author URL.
Wei C, Vanhatalo A, Kadach S, Stoyanov Z, Abu-Alghayth M, Black MI, Smallwood MJ, Rajaram R, Winyard PG, Jones AM, et al (2023). Reduction in blood pressure following acute dietary nitrate ingestion is correlated with increased red blood cell S-nitrosothiol concentrations.
Nitric Oxide,
138-139, 1-9.
Abstract:
Reduction in blood pressure following acute dietary nitrate ingestion is correlated with increased red blood cell S-nitrosothiol concentrations.
Dietary nitrate (NO3-) supplementation can enhance nitric oxide (NO) bioavailability and lower blood pressure (BP) in humans. The nitrite concentration ([NO2-]) in the plasma is the most commonly used biomarker of increased NO availability. However, it is unknown to what extent changes in other NO congeners, such as S-nitrosothiols (RSNOs), and in other blood components, such as red blood cells (RBC), also contribute to the BP lowering effects of dietary NO3-. We investigated the correlations between changes in NO biomarkers in different blood compartments and changes in BP variables following acute NO3- ingestion. Resting BP was measured and blood samples were collected at baseline, and at 1, 2, 3, 4 and 24 h following acute beetroot juice (∼12.8 mmol NO3-, ∼11 mg NO3-/kg) ingestion in 20 healthy volunteers. Spearman rank correlation coefficients were determined between the peak individual increases in NO biomarkers (NO3-, NO2-, RSNOs) in plasma, RBC and whole blood, and corresponding decreases in resting BP variables. No significant correlation was observed between increased plasma [NO2-] and reduced BP, but increased RBC [NO2-] was correlated with decreased systolic BP (rs = -0.50, P = 0.03). Notably, increased RBC [RSNOs] was significantly correlated with decreases in systolic (rs = -0.68, P = 0.001), diastolic (rs = -0.59, P = 0.008) and mean arterial pressure (rs = -0.64, P = 0.003). Fisher's z transformation indicated no difference in the strength of the correlations between increases in RBC [NO2-] or [RSNOs] and decreased systolic blood pressure. In conclusion, increased RBC [RSNOs] may be an important mediator of the reduction in resting BP observed following dietary NO3- supplementation.
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2021
Jones AM, Vanhatalo A, Seals DR, Rossman MJ, Piknova B, Jonvik KL (2021). Dietary Nitrate and Nitric Oxide Metabolism: Mouth, Circulation, Skeletal Muscle, and Exercise Performance.
Med Sci Sports Exerc,
53(2), 280-294.
Abstract:
Dietary Nitrate and Nitric Oxide Metabolism: Mouth, Circulation, Skeletal Muscle, and Exercise Performance.
Nitric oxide (NO) is a gaseous signaling molecule that plays an important role in myriad physiological processes, including the regulation of vascular tone, neurotransmission, mitochondrial respiration, and skeletal muscle contractile function. NO may be produced via the canonical NO synthase-catalyzed oxidation of l-arginine and also by the sequential reduction of nitrate to nitrite and then NO. The body's nitrate stores can be augmented by the ingestion of nitrate-rich foods (primarily green leafy vegetables). NO bioavailability is greatly enhanced by the activity of bacteria residing in the mouth, which reduce nitrate to nitrite, thereby increasing the concentration of circulating nitrite, which can be reduced further to NO in regions of low oxygen availability. Recent investigations have focused on promoting this nitrate-nitrite-NO pathway to positively affect indices of cardiovascular health and exercise tolerance. It has been reported that dietary nitrate supplementation with beetroot juice lowers blood pressure in hypertensive patients, and sodium nitrite supplementation improves vascular endothelial function and reduces the stiffening of large elastic arteries in older humans. Nitrate supplementation has also been shown to enhance skeletal muscle function and to improve exercise performance in some circumstances. Recently, it has been established that nitrate concentration in skeletal muscle is much higher than that in blood and that muscle nitrate stores are exquisitely sensitive to dietary nitrate supplementation and deprivation. In this review, we consider the possibility that nitrate represents an essential storage form of NO and discuss the integrated function of the oral microbiome, circulation, and skeletal muscle in nitrate-nitrite-NO metabolism, as well as the practical relevance for health and performance.
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Vanhatalo A, L'Heureux JE, Kelly J, Blackwell JR, Wylie LJ, Fulford J, Winyard PG, Williams DW, van der Giezen M, Jones AM, et al (2021). Network analysis of nitrate-sensitive oral microbiome reveals interactions with cognitive function and cardiovascular health across dietary interventions. Redox Biology, 41, 101933-101933.
Jones AM, Kirby BS, Clark IE, Rice HM, Fulkerson E, Wylie LJ, Wilkerson DP, Vanhatalo A, Wilkins BW (2021). Physiological demands of running at 2-hour marathon race pace.
J Appl Physiol (1985),
130(2), 369-379.
Abstract:
Physiological demands of running at 2-hour marathon race pace.
The requirements of running a 2-h marathon have been extensively debated but the actual physiological demands of running at ∼21.1 km/h have never been reported. We therefore conducted laboratory-based physiological evaluations and measured running economy (O2 cost) while running outdoors at ∼21.1 km/h, in world-class distance runners as part of Nike's "Breaking 2" marathon project. On separate days, 16 world-class male distance runners (age, 29 ± 4 yr; height, 1.72 ± 0.04 m; mass, 58.9 ± 3.3 kg) completed an incremental treadmill test for the assessment of V̇O2peak, O2 cost of submaximal running, lactate threshold and lactate turn-point, and a track test during which they ran continuously at 21.1 km/h. The laboratory-determined V̇O2peak was 71.0 ± 5.7 mL/kg/min with lactate threshold and lactate turn-point occurring at 18.9 ± 0.4 and 20.2 ± 0.6 km/h, corresponding to 83 ± 5% and 92 ± 3% V̇O2peak, respectively. Seven athletes were able to attain a steady-state V̇O2 when running outdoors at 21.1 km/h. The mean O2 cost for these athletes was 191 ± 19 mL/kg/km such that running at 21.1 km/h required an absolute V̇O2 of ∼4.0 L/min and represented 94 ± 3% V̇O2peak. We report novel data on the O2 cost of running outdoors at 21.1 km/h, which enables better modeling of possible marathon performances by elite athletes. Using the value for O2 cost measured in this study, a sub 2-h marathon would require a 59 kg runner to sustain a V̇O2 of approximately 4.0 L/min or 67 mL/kg/min.NEW & NOTEWORTHY We report the physiological characteristics and O2 cost of running overground at ∼21.1 km/h in a cohort of the world's best male distance runners. We provide new information on the absolute and relative O2 uptake required to run at 2-h marathon pace.
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Abu-Alghayth M, Vanhatalo A, Wylie LJ, McDonagh STJ, Thompson C, Kadach S, Kerr P, Smallwood MJ, Jones AM, Winyard PG, et al (2021). S-nitrosothiols, and other products of nitrate metabolism, are increased in multiple human blood compartments following ingestion of beetroot juice. Redox Biology, 43, 101974-101974.
2020
Veale DA (2020). A Pilot Study of Dietary Nitrate Supplementation in Anaemic Patients.
Abstract:
A Pilot Study of Dietary Nitrate Supplementation in Anaemic Patients
Introduction
Anaemia causes debilitating symptoms in people with cancer, partly through reduced tissue oxygenation. Nitrate supplementation, via reduction to nitrite then nitric oxide, attenuates the effects of systemic hypoxia on muscle metabolism. Nitric oxide also influences cerebral blood flow, neurotransmission and platelet aggregation.
Aims
To examine the feasibility of recruiting patients with cancer-related anaemia to a pilot study, and to estimate differences in outcome measures and predict resources required for a larger study investigating how nitrate supplementation affects thrombogenicity, muscle phosphocreatine recovery, exercise tolerance, cognition and quality of life.
Methods
This prospective, balanced randomised crossover study recruited 33 participants. Cycle ergometry, bloods, 31P-magnetic resonance spectroscopy and quality of life & cognition questionnaires were completed at two baseline visits and two visits post-supplementation with either nitrate-rich (BR) or nitrate-depleted (PL) beetroot juice.
Results
85% of 33 screened patients were enrolled. 26 completed all visits. Plasma nitrate concentration was 8.4±58.8µM (mean±SD) at baseline and 78±33.5µM post-BR (p=
Abstract.
Vanhatalo A, Blackwell J, Bailey SJ, Wylie LJ, Bond B, Nyberg M, Jones AM (2020). Dietary Nitrate Counteracts the Elevated Blood Pressure Response to Nitric Oxide Synthase Inhibition in Humans.
Author URL.
Vanhie J, Hedge E, Fanous J, Blackwell J, Keir D, Jones A, Vanhatalo A, Rice C, Kowalchuk J (2020). Dietary nitrate supplementation does not alter (C)over dotO(2p) gain during ramp incremental cycling exercise.
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2019
Morgan PT, Vanhatalo A, Bowtell JL, Jones AM, Bailey SJ (2019). Acetaminophen ingestion improves muscle activation and performance during a 3-min all-out cycling test.
Appl Physiol Nutr Metab,
44(4), 434-442.
Abstract:
Acetaminophen ingestion improves muscle activation and performance during a 3-min all-out cycling test.
Acute acetaminophen (ACT) ingestion has been shown to enhance cycling time-trial performance. The purpose of this study was to assess whether ACT ingestion enhances muscle activation and critical power (CP) during maximal cycling exercise. Sixteen active male participants completed two 3-min all-out tests against a fixed resistance on an electronically braked cycle ergometer 60 min after ingestion of 1 g of ACT or placebo (maltodextrin, PL). CP was estimated as the mean power output over the final 30 s of the test and W' (the curvature constant of the power-duration relationship) was estimated as the work done above CP. The femoral nerve was stimulated every 30 s to measure membrane excitability (M-wave) and surface electromyography (EMGRMS) was recorded continuously to infer muscle activation. Compared with PL, ACT ingestion increased CP (ACT: 297 ± 32 W vs. PL: 288 ± 31 W, P < 0.001) and total work done (ACT: 66.4 ± 6.5 kJ vs. PL: 65.4 ± 6.4 kJ, P = 0.03) without impacting W' (ACT: 13.1 ± 2.9 kJ vs. PL: 13.6 ± 2.4 kJ, P = 0.19) or the M-wave amplitude (P = 0.66) during the 3-min all-out cycling test. Normalised EMGRMS amplitude declined throughout the 3-min protocol in both PL and ACT conditions; however, the decline in EMGRMS amplitude was attenuated in the ACT condition, such that the EMGRMS amplitude was greater in ACT compared with PL over the last 60 s of the test (P = 0.04). These findings indicate that acute ACT ingestion might increase performance and CP during maximal cycling exercise by enhancing muscle activation.
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Morgan PT, Vanhatalo A, Bowtell JL, Jones AM, Bailey SJ (2019). Acute ibuprofen ingestion does not attenuate fatigue during maximal intermittent knee extensor or all-out cycling exercise.
Appl Physiol Nutr Metab,
44(2), 208-215.
Abstract:
Acute ibuprofen ingestion does not attenuate fatigue during maximal intermittent knee extensor or all-out cycling exercise.
Recent research suggests that acute consumption of pharmacological analgesics can improve exercise performance, but the ergogenic potential of ibuprofen (IBP) administration is poorly understood. This study tested the hypothesis that IBP administration would enhance maximal exercise performance. In one study, 13 physically active males completed 60 × 3-s maximal voluntary contractions (MVCs) of the knee extensors interspersed with 2-s passive recovery periods, on 2 occasions, with the critical torque (CT) estimated as the mean torque over the last 12 contractions (part A). In another study, 16 active males completed two 3-min all-out tests against a fixed resistance on an electronically braked cycle ergometer, with the critical power estimated from the mean power output over the final 30 s of the test (part B). All tests were completed 60 min after ingestion of maltodextrin (placebo, PL) or 400 mg of IBP. Peripheral nerve stimulation was administered at regular intervals and electromyography was measured throughout. For part A, mean torque (IBP: 60% ± 13% of pre-exercise MVC; PL: 58% ± 14% of pre-exercise MVC) and CT (IBP: 41% ± 16% of pre-exercise MVC; PL: 40% ± 15% of pre-exercise MVC) were not different between conditions (P > 0.05). For part B, end-test power output (IBP: 292 ± 28 W; PL: 288 ± 31 W) and work done (IBP: 65.9 ± 5.9 kJ; PL: 65.4 ± 6.4 kJ) during the 3-min all-out cycling tests were not different between conditions (all P > 0.05). For both studies, neuromuscular fatigue declined at a similar rate in both conditions (P > 0.05). In conclusion, acute ingestion of 400 mg of IBP does not improve single-leg or maximal cycling performance in healthy humans.
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Clark IE, Vanhatalo A, Thompson C, Wylie LJ, Bailey SJ, Kirby BS, Wilkins BW, Jones AM (2019). Changes in the power-duration relationship following prolonged exercise: estimation using conventional and all-out protocols and relationship with muscle glycogen.
Am J Physiol Regul Integr Comp Physiol,
317(1), R59-R67.
Abstract:
Changes in the power-duration relationship following prolonged exercise: estimation using conventional and all-out protocols and relationship with muscle glycogen.
It is not clear how the parameters of the power-duration relationship [critical power (CP) and W'] are influenced by the performance of prolonged endurance exercise. We used severe-intensity prediction trials (conventional protocol) and the 3-min all-out test (3MT) to measure CP and W' following 2 h of heavy-intensity cycling exercise and took muscle biopsies to investigate possible relationships to changes in muscle glycogen concentration ([glycogen]). Fourteen participants completed a rested 3MT to establish end-test power (Control-EP) and work done above EP (Control-WEP). Subsequently, on separate days, immediately following 2 h of heavy-intensity exercise, participants completed a 3MT to establish Fatigued-EP and Fatigued-WEP and three severe-intensity prediction trials to the limit of tolerance (Tlim) to establish Fatigued-CP and Fatigued-W'. A muscle biopsy was collected immediately before and after one of the 2-h exercise bouts. Fatigued-CP (256 ± 41 W) and Fatigued-EP (256 ± 52 W), and Fatigued-W' (15.3 ± 5.0 kJ) and Fatigued-WEP (14.6 ± 5.3 kJ), were not different (P > 0.05) but were ~11% and ~20% lower than Control-EP (287 ± 46 W) and Control-WEP (18.7 ± 4.7 kJ), respectively (P < 0.05). The change in muscle [glycogen] was not significantly correlated with the changes in either EP (r = 0.19) or WEP (r = 0.07). The power-duration relationship is adversely impacted by prolonged endurance exercise. The 3MT provides valid estimates of CP and W' following 2 h of heavy-intensity exercise, but the changes in these parameters are not primarily determined by changes in muscle [glycogen].
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Morgan PT, Bailey SJ, Banks RA, Fulford J, Vanhatalo A, Jones AM (2019). Contralateral fatigue during severe-intensity single-leg exercise: influence of acute acetaminophen ingestion.
Am J Physiol Regul Integr Comp Physiol,
317(2), R346-R354.
Abstract:
Contralateral fatigue during severe-intensity single-leg exercise: influence of acute acetaminophen ingestion.
Exhaustive single-leg exercise has been suggested to reduce time to task failure (Tlim) during subsequent exercise in the contralateral leg by exacerbating central fatigue development. We investigated the influence of acetaminophen (ACT), an analgesic that may blunt central fatigue development, on Tlim during single-leg exercise completed with and without prior fatiguing exercise of the contralateral leg. Fourteen recreationally active men performed single-leg severe-intensity knee-extensor exercise to Tlim on the left (Leg1) and right (Leg2) legs without prior contralateral fatigue and on Leg2 immediately following Leg1 (Leg2-CONTRA). The tests were completed following ingestion of 1-g ACT or maltodextrin [placebo (PL)] capsules. Intramuscular phosphorus-containing metabolites and substrates and muscle activation were assessed using 31P-MRS and electromyography, respectively. Tlim was not different between Leg1ACT and Leg1PL conditions (402 ± 101 vs. 390 ± 106 s, P = 0.11). There was also no difference in Tlim between Leg2ACT-CONTRA and Leg2PL-CONTRA (324 ± 85 vs. 311 ± 92 s, P = 0.10), but Tlim was shorter in Leg2ACT-CONTRA and Leg2PL-CONTRA than in Leg2CON (385 ± 104 s, both P < 0.05). There were no differences in intramuscular phosphorus-containing metabolites and substrates or muscle activation between Leg1ACT and Leg1PL and between Leg2ACT-CONTRA and Leg2PL-CONTRA (all P > 0.05). These findings suggest that levels of metabolic perturbation and muscle activation at Tlim are not different during single-leg severe-intensity knee-extensor exercise completed with or without prior fatiguing exercise of the contralateral leg. Despite contralateral fatigue, ACT ingestion did not alter neuromuscular responses, muscle metabolites, or exercise performance.
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Clark IE, Vanhatalo A, Thompson C, Joseph C, Black MI, Blackwell JR, Wylie LJ, Tan R, Bailey SJ, Wilkins BW, et al (2019). Dynamics of the power-duration relationship during prolonged endurance exercise and influence of carbohydrate ingestion.
J Appl Physiol (1985),
127(3), 726-736.
Abstract:
Dynamics of the power-duration relationship during prolonged endurance exercise and influence of carbohydrate ingestion.
We tested the hypotheses that the parameters of the power-duration relationship, estimated as the end-test power (EP) and work done above EP (WEP) during a 3-min all-out exercise test (3MT), would be reduced progressively after 40 min, 80 min, and 2 h of heavy-intensity cycling and that carbohydrate (CHO) ingestion would attenuate the reduction in EP and WEP. Sixteen participants completed a 3MT without prior exercise (control), immediately after 40 min, 80 min, and 2 h of heavy-intensity exercise while consuming a placebo beverage, and also after 2 h of heavy-intensity exercise while consuming a CHO supplement (60 g/h CHO). There was no difference in EP measured without prior exercise (260 ± 37 W) compared with EP after 40 min (268 ± 39 W) or 80 min (260 ± 40 W) of heavy-intensity exercise; however, after 2 h EP was 9% lower compared with control (236 ± 47 W; P < 0.05). There was no difference in WEP measured without prior exercise (17.9 ± 3.3 kJ) compared with after 40 min of heavy-intensity exercise (16.1 ± 3.3 kJ), but WEP was lower (P < 0.05) than control after 80 min (14.7 ± 2.9 kJ) and 2 h (13.8 ± 2.7 kJ). Compared with placebo, CHO ingestion negated the reduction of EP following 2 h of heavy-intensity exercise (254 ± 49 W) but had no effect on WEP (13.5 ± 3.4 kJ). These results reveal a different time course for the deterioration of EP and WEP during prolonged endurance exercise and indicate that EP is sensitive to CHO availability.NEW & NOTEWORTHY the parameters of the power-duration relationship [critical power (CP) and the curvature constant (W')] have typically been considered to be static. Here we report the time course for reductions in CP and W', as estimated with the 3-min all-out cycle test, during 2 h of heavy-intensity exercise. We also show that carbohydrate ingestion during exercise preserves CP, but not W', without altering muscle glycogen depletion. These results provide new mechanistic and practical insight into the power-duration curve and its relationship to exercise-related fatigue development.
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Wylie LJ, Park JW, Vanhatalo A, Kadach S, Black MI, Stoyanov Z, Schechter AN, Jones AM, Piknova B (2019). Human skeletal muscle nitrate store: influence of dietary nitrate supplementation and exercise.
J Physiol,
597(23), 5565-5576.
Abstract:
Human skeletal muscle nitrate store: influence of dietary nitrate supplementation and exercise.
KEY POINTS: Nitric oxide (NO), a potent vasodilator and a regulator of many physiological processes, is produced in mammals both enzymatically and by reduction of nitrite and nitrate ions. We have previously reported that, in rodents, skeletal muscle serves as a nitrate reservoir, with nitrate levels greatly exceeding those in blood or other internal organs, and with nitrate being reduced to NO during exercise. In the current study, we show that nitrate concentration is substantially greater in skeletal muscle than in blood and is elevated further by dietary nitrate ingestion in human volunteers. We also show that high-intensity exercise results in a reduction in the skeletal muscle nitrate store following supplementation, likely as a consequence of its reduction to nitrite and NO. We also report the presence of sialin, a nitrate transporter, and xanthine oxidoreductase in human skeletal muscle, indicating that muscle has the necessary apparatus for nitrate transport, storage and metabolism. ABSTRACT: Rodent skeletal muscle contains a large store of nitrate that can be augmented by the consumption of dietary nitrate. This muscle nitrate reservoir has been found to be an important source of nitrite and nitric oxide (NO) via its reduction by tissue xanthine oxidoreductase. To explore if this pathway is also active in human skeletal muscle during exercise, and if it is sensitive to local nitrate availability, we assessed exercise-induced changes in muscle nitrate and nitrite concentrations in young healthy humans, under baseline conditions and following dietary nitrate consumption. We found that baseline nitrate and nitrite concentrations were far higher in muscle than in plasma (∼4-fold and ∼29-fold, respectively), and that the consumption of a single bolus of dietary nitrate (12.8 mmol) significantly elevated nitrate concentration in both plasma (∼19-fold) and muscle (∼5-fold). Consistent with these observations, and with previous suggestions of active muscle nitrate transport, we present western blot data to show significant expression of the active nitrate/nitrite transporter sialin in human skeletal muscle. Furthermore, we report an exercise-induced reduction in human muscle nitrate concentration (by ∼39%), but only in the presence of an increased muscle nitrate store. Our results indicate that human skeletal muscle nitrate stores are sensitive to dietary nitrate intake and may contribute to NO generation during exercise. Together, these findings suggest that skeletal muscle plays an important role in the transport, storage and metabolism of nitrate in humans.
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McDonagh STJ, Wylie LJ, Thompson C, Vanhatalo A, Jones AM (2019). Potential benefits of dietary nitrate ingestion in healthy and clinical populations: a brief review.
Eur J Sport Sci,
19(1), 15-29.
Abstract:
Potential benefits of dietary nitrate ingestion in healthy and clinical populations: a brief review.
This article provides an overview of the current literature relating to the efficacy of dietary nitrate (NO3-) ingestion in altering aspects of cardiovascular and metabolic health and exercise capacity in healthy and diseased individuals. The consumption of NO3--rich vegetables, such as spinach and beetroot, have been variously shown to promote nitric oxide bioavailability, reduce systemic blood pressure, enhance tissue blood flow, modulate muscle O2 utilisation and improve exercise tolerance both in normoxia and in hypoxia, as is commonly observed in a number of disease states. NO3- ingestion may, therefore, act as a natural means for augmenting performance and attenuating complications associated with limited O2 availability or transport, hypertension and the metabolic syndrome. Recent studies indicate that dietary NO3- might also augment intrinsic skeletal muscle contractility and improve the speed and power of muscle contraction. Moreover, several investigations suggest that NO3- supplementation may improve aspects of cognitive performance both at rest and during exercise. Collectively, these observations position NO3- as more than a putative ergogenic aid and suggest that increasing natural dietary NO3- intake may act as a prophylactic in countering the predations of senescence and certain cardiovascular-metabolic diseases.
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Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A (2019). Response to considerations regarding Maximal Lactate Steady State determination before redefining the gold-standard.
Physiol Rep,
7(22).
Abstract:
Response to considerations regarding Maximal Lactate Steady State determination before redefining the gold-standard.
We reinforce the key messages in our earlier review paper that critical power, rather than maximal lactate steady state, provides the better index for defining steady-state vs non-steady state physiological behaviour during exercise.
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Morgan PT, Black MI, Bailey SJ, Jones AM, Vanhatalo A (2019). Road cycle TT performance: Relationship to the power-duration model and association with FTP.
Journal of Sports Sciences,
37(8), 902-910.
Abstract:
Road cycle TT performance: Relationship to the power-duration model and association with FTP
Purpose: to determine the accuracy of critical power (CP) and Wʹ (the curvature constant of the power-duration relationship) derived from self-paced time-trial (TT) prediction trials using mobile power meters to predict 16.1-km road cycling TT performance. This study also aimed to assess the agreement between functional threshold power (FTP) and CP. Methods: Twelve competitive male cyclists completed an incremental test to exhaustion, a FTP test and 4–5 self-paced TT bouts on a stationary bike within the lab, and a 16.1 km road TT, using mobile power meters. Results: CP and Wʹ derived from the power-duration relationship closely predicted TT performance. The 16.1-km road TT completion time (26.7 ± 2.2 min) was not significantly different from and was significantly correlated with the predicted time-to-completion (27.5 ± 3.3 min, r = 0.89, P 0.05); however, the limits of agreement between CP and FTP were 30 to -36 W. Discussion: the findings of this study indicate that CP and Wʹ determined using mobile power meters during maximal, self-paced TT prediction trials can be used to accurately predict 16.1-km cycling performance, supporting the application of the CP and Wʹ for performance prediction. However, the limits of agreement were too large to consider FTP and CP interchangeable.
Abstract.
Jones AM, Burnley M, Black MI, Poole DC, Vanhatalo A (2019). The maximal metabolic steady state: redefining the 'gold standard'.
Physiol Rep,
7(10).
Abstract:
The maximal metabolic steady state: redefining the 'gold standard'.
The maximal lactate steady state (MLSS) and the critical power (CP) are two widely used indices of the highest oxidative metabolic rate that can be sustained during continuous exercise and are often considered to be synonymous. However, while perhaps having similarities in principle, methodological differences in the assessment of these parameters typically result in MLSS occurring at a somewhat lower power output or running speed and exercise at CP being sustainable for no more than approximately 20-30 min. This has led to the view that CP overestimates the 'actual' maximal metabolic steady state and that MLSS should be considered the 'gold standard' metric for the evaluation of endurance exercise capacity. In this article we will present evidence consistent with the contrary conclusion: i.e. that (1) as presently defined, MLSS naturally underestimates the actual maximal metabolic steady state; and (2) CP alone represents the boundary between discrete exercise intensity domains within which the dynamic cardiorespiratory and muscle metabolic responses to exercise differ profoundly. While both MLSS and CP may have relevance for athletic training and performance, we urge that the distinction between the two concepts/metrics be better appreciated and that comparisons between MLSS and CP, undertaken in the mistaken belief that they are theoretically synonymous, is discontinued. CP represents the genuine boundary separating exercise in which physiological homeostasis can be maintained from exercise in which it cannot, and should be considered the gold standard when the goal is to determine the maximal metabolic steady state.
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Clark IE, Goulding RP, DiMenna FJ, Bailey SJ, Jones MI, Fulford J, McDonagh STJ, Jones AM, Vanhatalo A (2019). Time-trial performance is not impaired in either competitive athletes or untrained individuals following a prolonged cognitive task.
Eur J Appl Physiol,
119(1), 149-161.
Abstract:
Time-trial performance is not impaired in either competitive athletes or untrained individuals following a prolonged cognitive task.
It has been reported that mental fatigue decreases exercise performance during high-intensity constant-work-rate exercise (CWR) and self-paced time trials (TT) in recreationally-trained individuals. The purpose of this study was to determine whether performance is impaired following a prolonged cognitive task in individuals trained for competitive sport. Ten trained competitive athletes (ATH) and ten untrained healthy men (UNT) completed a 6-min severe-intensity CWR followed by a 6-min cycling TT immediately following cognitive tasks designed to either perturb (Stroop colour-word task and N-back task; PCT) or maintain a neutral (documentary watching; CON) mental state. UNT had a higher heart rate (75 ± 9 v. 69 ± 7 bpm; P = 0.002) and a lower positive affect PANAS score (19.9 ± 7.5 v. 24.3 ± 4.6; P = 0.036) for PCT compared to CON. ATH showed no difference in heart rate, but had a higher negative affect score for PCT compared to CON (15.1 ± 3.7 v. 12.2 ± 2.7; P = 0.029). Pulmonary O2 uptake during CWR was not different between PCT and CON for ATH or UNT. Work completed during TT was not different between PCT and CON for ATH (PCT 103 ± 12 kJ; CON 102 ± 12 kJ; P > 0.05) or UNT (PCT 75 ± 11 kJ; CON 74 ± 12 kJ; P > 0.05). Compared to CON, during PCT, UNT showed unchanged psychological stress responses, whereas ATH demonstrated increased psychological stress responses. However, regardless of this distinction, exercise performance was not affected by PCT in either competitive athletes or untrained individuals.
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2018
Morgan PT, Bowtell JL, Vanhatalo A, Jones AM, Bailey SJ (2018). Acute acetaminophen ingestion improves performance and muscle activation during maximal intermittent knee extensor exercise.
Eur J Appl Physiol,
118(3), 595-605.
Abstract:
Acute acetaminophen ingestion improves performance and muscle activation during maximal intermittent knee extensor exercise.
AIM: Acetaminophen is a commonly used medicine for pain relief and emerging evidence suggests that it may improve endurance exercise performance. This study investigated some of the physiological mechanisms by which acute acetaminophen ingestion might blunt muscle fatigue development. METHODS: Thirteen active males completed 60 × 3 s maximum voluntary contractions (MVC) of the knee extensors with each contraction separated by a 2 s passive recovery period. This protocol was completed 60 min after ingesting 1 g of maltodextrin (placebo) or 1 g of acetaminophen on two separate visits. Peripheral nerve stimulation was administered every 6th contraction for assessment of neuromuscular fatigue development, with the critical torque (CT), which reflects the maximal sustainable rate of oxidative metabolism, taken as the mean torque over the last 12 contractions. Surface electromyography was recorded continuously as a measure of muscle activation. RESULTS: Mean torque (61 ± 11 vs. 58 ± 14% pre-exercise MVC) and CT (44 ± 13 vs. 40 ± 15% pre-exercise MVC) were greater in the acetaminophen trial compared to placebo (both P 0.05). However, the decline in electromyography amplitude was attenuated in the acetaminophen trial, with electromyography amplitude being greater compared to placebo from 210 s onwards (P
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Tan R, Wylie LJ, Thompson C, Blackwell JR, Bailey SJ, Vanhatalo A, Jones AM (2018). Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O2 uptake.
J Appl Physiol (1985),
124(5), 1254-1263.
Abstract:
Beetroot juice ingestion during prolonged moderate-intensity exercise attenuates progressive rise in O2 uptake.
Nitrate-rich beetroot juice (BR) supplementation has been shown to increase biomarkers of nitric oxide availability with implications for the physiological responses to exercise. We hypothesized that BR supplementation before and during prolonged moderate-intensity exercise would maintain an elevated plasma nitrite concentration ([[Formula: see text]]), attenuate the expected progressive increase in V̇o2 over time, and improve performance in a subsequent time trial (TT). In a double-blind, randomized, crossover design, 12 men completed 2 h of moderate-intensity cycle exercise followed by a 100-kJ TT in three conditions: 1) BR before and 1 h into exercise (BR + BR); 2) BR before and placebo (PL) 1 h into exercise (BR + PL); and 3) PL before and 1 h into exercise (PL + PL). During the 2-h moderate-intensity exercise bout, plasma [[Formula: see text]] declined by ~17% in BR + PL but increased by ~8% in BR + BR such that, at 2 h, plasma [[Formula: see text]] was greater in BR + BR than both BR + PL and PL + PL ( P < 0.05). V̇o2 was not different among conditions over the first 90 min of exercise but was lower at 120 min in BR + BR (1.73 ± 0.24 l/min) compared with BR + PL (1.80 ± 0.21 l/min; P = 0.08) and PL + PL (1.83 ± 0.27 l/min; P < 0.01). The decline in muscle glycogen concentration over the 2-h exercise bout was attenuated in BR + BR (~28% decline) compared with BR + PL (~44% decline) and PL + PL (~44% decline; n = 9, P < 0.05). TT performance was not different among conditions ( P > 0.05). BR supplementation before and during prolonged moderate-intensity exercise attenuated the progressive rise in V̇o2 over time and appeared to reduce muscle glycogen depletion but did not enhance subsequent TT performance. NEW & NOTEWORTHY We show for the first time that ingestion of nitrate during exercise preserves elevated plasma [nitrite] and negates the progressive rise in O2 uptake during prolonged moderate-intensity exercise.
Abstract.
Author URL.
Craig JC, Vanhatalo A, Burnley M, Jones AM, Poole DC (2018). Critical Power: Possibly the Most Important Fatigue Threshold in Exercise Physiology. Possibly the Most Important Fatigue Threshold in Exercise Physiology. In (Ed)
Muscle and Exercise Physiology, 159-181.
Abstract:
Critical Power: Possibly the Most Important Fatigue Threshold in Exercise Physiology. Possibly the Most Important Fatigue Threshold in Exercise Physiology.
Abstract.
Jones AM, Thompson C, Wylie LJ, Vanhatalo A (2018). Dietary Nitrate and Physical Performance.
Annu Rev Nutr,
38, 303-328.
Abstract:
Dietary Nitrate and Physical Performance.
Nitric oxide (NO) plays a plethora of important roles in the human body. Insufficient production of NO (for example, during older age and in various disease conditions) can adversely impact health and physical performance. In addition to its endogenous production through the oxidation of l-arginine, NO can be formed nonenzymatically via the reduction of nitrate and nitrite, and the storage of these anions can be augmented by the consumption of nitrate-rich foodstuffs such as green leafy vegetables. Recent studies indicate that dietary nitrate supplementation, administered most commonly in the form of beetroot juice, can ( a) improve muscle efficiency by reducing the O2 cost of submaximal exercise and thereby improve endurance exercise performance and ( b) enhance skeletal muscle contractile function and thereby improve muscle power and sprint exercise performance. This review describes the physiological mechanisms potentially responsible for these effects, outlines the circumstances in which ergogenic effects are most likely to be evident, and discusses the effects of dietary nitrate supplementation on physical performance in a range of human populations.
Abstract.
Author URL.
Thompson C, Vanhatalo A, Kadach S, Wylie LJ, Fulford J, Ferguson SK, Blackwell JR, Bailey SJ, Jones AM (2018). Discrete physiological effects of beetroot juice and potassium nitrate supplementation following 4-wk sprint interval training.
J Appl Physiol (1985),
124(6), 1519-1528.
Abstract:
Discrete physiological effects of beetroot juice and potassium nitrate supplementation following 4-wk sprint interval training.
The physiological and exercise performance adaptations to sprint interval training (SIT) may be modified by dietary nitrate ([Formula: see text]) supplementation. However, it is possible that different types of [Formula: see text] supplementation evoke divergent physiological and performance adaptations to SIT. The purpose of this study was to compare the effects of 4-wk SIT with and without concurrent dietary [Formula: see text] supplementation administered as either [Formula: see text]-rich beetroot juice (BR) or potassium [Formula: see text] (KNO3). Thirty recreationally active subjects completed a battery of exercise tests before and after a 4-wk intervention in which they were allocated to one of three groups: 1) SIT undertaken without dietary [Formula: see text] supplementation (SIT); 2) SIT accompanied by concurrent BR supplementation (SIT + BR); or 3) SIT accompanied by concurrent KNO3 supplementation (SIT + KNO3). During severe-intensity exercise, V̇o2peak and time to task failure were improved to a greater extent with SIT + BR than SIT and SIT + KNO3 ( P < 0.05). There was also a greater reduction in the accumulation of muscle lactate at 3 min of severe-intensity exercise in SIT + BR compared with SIT + KNO3 ( P < 0.05). Plasma [Formula: see text] concentration fell to a greater extent during severe-intensity exercise in SIT + BR compared with SIT and SIT + KNO3 ( P < 0.05). There were no differences between groups in the reduction in the muscle phosphocreatine recovery time constant from pre- to postintervention ( P > 0.05). These findings indicate that 4-wk SIT with concurrent BR supplementation results in greater exercise capacity adaptations compared with SIT alone and SIT with concurrent KNO3 supplementation. This may be the result of greater NO-mediated signaling in SIT + BR compared with SIT + KNO3. NEW & NOTEWORTHY We compared the influence of different forms of dietary nitrate supplementation on the physiological and performance adaptations to sprint interval training (SIT). Compared with SIT alone, supplementation with nitrate-rich beetroot juice, but not potassium [Formula: see text], enhanced some physiological adaptations to training.
Abstract.
Author URL.
Keane KM, Bailey SJ, Vanhatalo A, Jones AM, Howatson G (2018). Effects of Montmorency Tart Cherry (L. Prunus Cerasus) Consumption on Nitric Oxide Biomarkers and Exercise Performance.
Author URL.
Clark IE, Vanhatalo A, Bailey SJ, Wylie LJ, Kirby BS, Wilkins BW, Jones AM (2018). Effects of Two Hours of Heavy-Intensity Exercise on the Power-Duration Relationship.
Med Sci Sports Exerc,
50(8), 1658-1668.
Abstract:
Effects of Two Hours of Heavy-Intensity Exercise on the Power-Duration Relationship.
INTRODUCTION: Changes in the parameters of the power-time relationship (critical power (CP) and W') during endurance exercise would have important implications for performance. We tested the hypotheses that CP and W', estimated using the end-test power (EP) and the work done above EP (WEP), respectively, during a the 3-min all-out test (3MT), can be reliably determined, and would be lower, after completing 2 h of heavy-intensity exercise. METHODS: in study 1, six cyclists completed a 3MT immediately after 2 h of heavy-intensity exercise on two occasions to establish the reliability of EP and WEP. In study 2, nine cyclists completed a control 3MT, and a fatigued 3MT and constant power output tests to 30 min or the limit of tolerance (Tlim) below and above F-EP after 2 h of heavy-intensity exercise. RESULTS: in study 1, EP (273 ± 52 vs 276 ± 58 W) and WEP (12.4 ± 4.3 vs 12.8 ± 4.3 kJ) after 2 h of heavy-intensity exercise were not different (P > 0.05) and were highly correlated (r = 0.99; P < 0.001). In study 2, both EP (F-EP: 282 ± 52 vs C-EP: 306 ± 56 W; P < 0.01) and WEP (F-WEP: 14.7 ± 4.9 vs C-WEP: 18.3 ± 4.1 kJ; P < 0.05) were lower after 2-h heavy-intensity exercise. However, maximum O2 uptake was not achieved during exercise >F-EP and Tlim was shorter than 30 min during exercise
Abstract.
Author URL.
Keane KM, Bailey SJ, Vanhatalo A, Jones AM, Howatson G (2018). Effects of montmorency tart cherry (L. Prunus Cerasus) consumption on nitric oxide biomarkers and exercise performance.
Scand J Med Sci Sports,
28(7), 1746-1756.
Abstract:
Effects of montmorency tart cherry (L. Prunus Cerasus) consumption on nitric oxide biomarkers and exercise performance.
The purpose of this study was to investigate the effects of Montmorency tart cherry juice (MC) on nitric oxide (NO) biomarkers, vascular function, and exercise performance. In a randomized, double-blind, placebo (PLA)-controlled, crossover study, 10 trained cyclists (mean ± SD; V˙O2peak 59.0 ± 7.0 mL/kg/min) acutely ingested 30 mL of either MC or PLA following dietary restrictions of polyphenol-rich compounds and completed 6-minutes moderate- and severe-intensity cycling bouts 1.5 hour post-ingestion on 2 occasions for each experimental condition. The severe-intensity cycling test was continued to exhaustion on 1 occasion and immediately followed by a 60-seconds all-out sprint on the other occasion. Blood pressure, pulse wave measures, tissue oxygenation index, and plasma nitrite concentration were assessed pre- and 1.5 hour post-ingestion. Time to exhaustion was not different between conditions (P > .05), but peak power over the first 20 seconds (363 ± 42 vs 330 ± 26 W) and total work completed during the 60-seconds all-out sprint (21 ± 3 vs 19 ± 3 kJ) were 10% higher in the MC trial compared to the PLA trial (P
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Author URL.
Brock K, Antonellis P, Black MI, DiMenna FJ, Vanhatalo A, Jones AM, Bailey SJ (2018). Improvement of Oxygen-Uptake Kinetics and Cycling Performance with Combined Prior Exercise and Fast Start.
Int J Sports Physiol Perform,
13(3), 305-312.
Abstract:
Improvement of Oxygen-Uptake Kinetics and Cycling Performance with Combined Prior Exercise and Fast Start.
PURPOSE: to investigate whether oxygen-uptake ([Formula: see text]) kinetics and simulated 4-km cycling performance are synergistically improved by prior "priming" exercise and an all-out starting strategy. METHODS: Nine men completed 4 target work trials (114 ± 17 kJ) to assess [Formula: see text] kinetics and cycling performance in a repeated-measures, crossover experimental design. Trials were initiated with either a 12-s all-out start or a self-selected start and preceded by prior severe-intensity (70%Δ) priming exercise or no priming exercise. RESULTS: the [Formula: see text] mean response time (MRT) was lower (indicative of faster [Formula: see text] kinetics) in the all-out primed condition (20 ± 6 s) than in the all-out unprimed (23 ± 6 s), self-paced-unprimed (42 ± 13 s), and self-paced-primed (42 ± 11 s) trials (P
Abstract.
Author URL.
McDonagh STJ, Wylie LJ, Webster JMA, Vanhatalo A, Jones AM (2018). Influence of dietary nitrate food forms on nitrate metabolism and blood pressure in healthy normotensive adults.
Nitric Oxide,
72, 66-74.
Abstract:
Influence of dietary nitrate food forms on nitrate metabolism and blood pressure in healthy normotensive adults.
Inorganic nitrate (NO3-) supplementation has been shown to improve cardiovascular health indices in healthy adults. The purpose of this study was to investigate how the vehicle of NO3- administration can influence NO3- metabolism and the subsequent blood pressure response. Ten healthy males consumed an acute equimolar dose of NO3- (∼5.76 mmol) in the form of a concentrated beetroot juice drink (BR; 55 mL), a non-concentrated beetroot juice drink (BL; 456 mL) and a solid beetroot flapjack (BF; 60 g). A drink containing soluble beetroot crystals (BC; ∼1.40 mmol NO3-) and a control drink (CON; 70 mL deionised water) were also ingested. BP and plasma, salivary and urinary [NO3-] and [NO2-] were determined before and up to 24 h after ingestion. All NO3--rich vehicles elevated plasma, salivary and urinary nitric oxide metabolites compared with baseline and CON (P
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Author URL.
Vanhatalo A, Blackwell JR, L'Heureux JE, Williams DW, Smith A, van der Giezen M, Winyard PG, Kelly J, Jones AM (2018). Nitrate-responsive oral microbiome modulates nitric oxide homeostasis and blood pressure in humans.
Free Radic Biol Med,
124, 21-30.
Abstract:
Nitrate-responsive oral microbiome modulates nitric oxide homeostasis and blood pressure in humans.
Imbalances in the oral microbial community have been associated with reduced cardiovascular and metabolic health. A possible mechanism linking the oral microbiota to health is the nitrate (NO3-)-nitrite (NO2-)-nitric oxide (NO) pathway, which relies on oral bacteria to reduce NO3- to NO2-. NO (generated from both NO2- and L-arginine) regulates vascular endothelial function and therefore blood pressure (BP). By sequencing bacterial 16S rRNA genes we examined the relationships between the oral microbiome and physiological indices of NO bioavailability and possible changes in these variables following 10 days of NO3- (12 mmol/d) and placebo supplementation in young (18-22 yrs) and old (70-79 yrs) normotensive humans (n = 18). NO3- supplementation altered the salivary microbiome compared to placebo by increasing the relative abundance of Proteobacteria (+225%) and decreasing the relative abundance of Bacteroidetes (-46%; P
Abstract.
Author URL.
Black MI, Jones AM, Morgan PT, Bailey SJ, Fulford J, Vanhatalo A (2018). The effects of β-alanine supplementation on muscle pH and the power-duration relationship during high-intensity exercise.
Frontiers in Physiology,
9(FEB).
Abstract:
The effects of β-alanine supplementation on muscle pH and the power-duration relationship during high-intensity exercise
Purpose: to investigate the influence of β-alanine (BA) supplementation on muscle carnosine content, muscle pH and the power-duration relationship (i.e. critical power and W'). Methods: in a double-blind, randomized, placebo-controlled study, 20 recreationally-active males (22 ± 3 y, V°O2peak 3.73 ± 0.44 L·min-1) ingested either BA (6.4 g/d for 28 d) or placebo (PL) (6.4 g/d) for 28 d. Subjects completed an incremental test and two 3-min all-out tests separated by 1-min on a cycle ergometer pre- and post-supplementation. Muscle pH was assessed using 31P-magnetic resonance spectroscopy (MRS) during incremental (INC KEE) and intermittent knee-extension exercise (INT KEE). Muscle carnosine content was determined using 1H-MRS. Results: There were no differences in the change in muscle carnosine content from pre- to post-intervention (PL: 1 ± 16% vs. BA: -4 ± 25%) or in muscle pH during INC KEE or INT KEE (P > 0.05) between PL and BA, but blood pH (PL: -0.06 ± 0.10 vs. BA: 0.09 ± 0.13) during the incremental test was elevated post-supplementation in the BA group only (P < 0.05). The changes from pre- to post-supplementation in critical power (PL: -8 ± 18 W vs. BA: -6 ± 17 W) and W' (PL: 1.8 ± 3.3 kJ vs. BA: 1.5 ± 1.7 kJ) were not different between groups. No relationships were detected between muscle carnosine content and indices of exercise performance. Conclusions: BA supplementation had no significant effect on muscle carnosine content and no influence on intramuscular pH during incremental or high-intensity intermittent knee-extension exercise. The small increase in blood pH following BA supplementation was not sufficient to significantly alter the power-duration relationship or exercise performance.
Abstract.
2017
Thompson C, Wylie LJ, Blackwell JR, Fulford J, Black MI, Kelly J, McDonagh STJ, Carter J, Bailey SJ, Vanhatalo A, et al (2017). Influence of dietary nitrate supplementation on physiological and muscle metabolic adaptations to sprint interval training.
J Appl Physiol (1985),
122(3), 642-652.
Abstract:
Influence of dietary nitrate supplementation on physiological and muscle metabolic adaptations to sprint interval training.
We hypothesized that 4 wk of dietary nitrate supplementation would enhance exercise performance and muscle metabolic adaptations to sprint interval training (SIT). Thirty-six recreationally active subjects, matched on key variables at baseline, completed a series of exercise tests before and following a 4-wk period in which they were allocated to one of the following groups: 1) SIT and [Formula: see text]-depleted beetroot juice as a placebo (SIT+PL); 2) SIT and [Formula: see text]-rich beetroot juice (~13 mmol [Formula: see text]/day; SIT+BR); or 3) no training and [Formula: see text]-rich beetroot juice (NT+BR). During moderate-intensity exercise, pulmonary oxygen uptake was reduced by 4% following 4 wk of SIT+BR and NT+BR (P < 0.05) but not SIT+PL. The peak work rate attained during incremental exercise increased more in SIT+BR than in SIT+PL (P < 0.05) or NT+BR (P < 0.001). The reduction in muscle and blood [lactate] and the increase in muscle pH from preintervention to postintervention were greater at 3 min of severe-intensity exercise in SIT+BR compared with SIT+PL and NT+BR (P < 0.05). However, the change in severe-intensity exercise performance was not different between SIT+BR and SIT+PL (P > 0.05). The relative proportion of type IIx muscle fibers in the vastus lateralis muscle was reduced in SIT+BR only (P < 0.05). These findings suggest that BR supplementation may enhance some aspects of the physiological adaptations to SIT.NEW & NOTEWORTHY We investigated the influence of nitrate-rich and nitrate-depleted beetroot juice on the muscle metabolic and physiological adaptations to 4 wk of sprint interval training. Compared with placebo, dietary nitrate supplementation reduced the O2 cost of submaximal exercise, resulted in greater improvement in incremental (but not severe-intensity) exercise performance, and augmented some muscle metabolic adaptations to training. Nitrate supplementation may facilitate some of the physiological responses to sprint interval training.
Abstract.
Author URL.
Black MI, Jones AM, Blackwell JR, Bailey SJ, Wylie LJ, McDonagh STJ, Thompson C, Kelly J, Sumners P, Mileva KN, et al (2017). Muscle metabolic and neuromuscular determinants of fatigue during cycling in different exercise intensity domains.
J Appl Physiol (1985),
122(3), 446-459.
Abstract:
Muscle metabolic and neuromuscular determinants of fatigue during cycling in different exercise intensity domains.
Lactate or gas exchange threshold (GET) and critical power (CP) are closely associated with human exercise performance. We tested the hypothesis that the limit of tolerance (Tlim) during cycle exercise performed within the exercise intensity domains demarcated by GET and CP is linked to discrete muscle metabolic and neuromuscular responses. Eleven men performed a ramp incremental exercise test, 4-5 severe-intensity (SEV; >CP) constant-work-rate (CWR) tests until Tlim, a heavy-intensity (HVY; GET) CWR test until Tlim, and a moderate-intensity (MOD;. 0.05) muscle metabolic milieu (i.e. low pH and [PCr] and high [lactate]) was attained at Tlim (approximately 2-14 min) for all SEV exercise bouts. The muscle metabolic perturbation was greater at Tlim following SEV compared with HVY, and also following SEV and HVY compared with MOD (all P < 0.05). The normalized M-wave amplitude for the vastus lateralis (VL) muscle decreased to a similar extent following SEV (-38 ± 15%), HVY (-68 ± 24%), and MOD (-53 ± 29%), (P > 0.05). Neural drive to the VL increased during SEV (4 ± 4%; P < 0.05) but did not change during HVY or MOD (P > 0.05). During SEV and HVY, but not MOD, the rates of change in M-wave amplitude and neural drive were correlated with changes in muscle metabolic ([PCr], [lactate]) and blood ionic/acid-base status ([lactate], [K+]) (P < 0.05). The results of this study indicate that the metabolic and neuromuscular determinants of fatigue development differ according to the intensity domain in which the exercise is performed.NEW & NOTEWORTHY the gas exchange threshold and the critical power demarcate discrete exercise intensity domains. For the first time, we show that the limit of tolerance during whole-body exercise within these domains is characterized by distinct metabolic and neuromuscular responses. Fatigue development during exercise greater than critical power is associated with the attainment of consistent "limiting" values of muscle metabolites, whereas substrate availability and limitations to muscle activation may constrain performance at lower intensities.
Abstract.
Author URL.
Jones AM, Vanhatalo A (2017). The 'Critical Power' Concept: Applications to Sports Performance with a Focus on Intermittent High-Intensity Exercise.
Sports Med,
47(Suppl 1), 65-78.
Abstract:
The 'Critical Power' Concept: Applications to Sports Performance with a Focus on Intermittent High-Intensity Exercise.
The curvilinear relationship between power output and the time for which it can be sustained is a fundamental and well-known feature of high-intensity exercise performance. This relationship 'levels off' at a 'critical power' (CP) that separates power outputs that can be sustained with stable values of, for example, muscle phosphocreatine, blood lactate, and pulmonary oxygen uptake ([Formula: see text]), from power outputs where these variables change continuously with time until their respective minimum and maximum values are reached and exercise intolerance occurs. The amount of work that can be done during exercise above CP (the so-called W') is constant but may be utilized at different rates depending on the proximity of the exercise power output to CP. Traditionally, this two-parameter CP model has been employed to provide insights into physiological responses, fatigue mechanisms, and performance capacity during continuous constant power output exercise in discrete exercise intensity domains. However, many team sports (e.g. basketball, football, hockey, rugby) involve frequent changes in exercise intensity and, even in endurance sports (e.g. cycling, running), intensity may vary considerably with environmental/course conditions and pacing strategy. In recent years, the appeal of the CP concept has been broadened through its application to intermittent high-intensity exercise. With the assumptions that W' is utilized during work intervals above CP and reconstituted during recovery intervals below CP, it can be shown that performance during intermittent exercise is related to four factors: the intensity and duration of the work intervals and the intensity and duration of the recovery intervals. However, while the utilization of W' may be assumed to be linear, studies indicate that the reconstitution of W' may be curvilinear with kinetics that are highly variable between individuals. This has led to the development of a new CP model for intermittent exercise in which the balance of W' remaining ([Formula: see text]) may be calculated with greater accuracy. Field trials of athletes performing stochastic exercise indicate that this [Formula: see text] model can accurately predict the time at which W' tends to zero and exhaustion is imminent. The [Formula: see text] model potentially has important applications in the real-time monitoring of athlete fatigue progression in endurance and team sports, which may inform tactics and influence pacing strategy.
Abstract.
Author URL.
2016
Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM (2016). Critical Power: an Important Fatigue Threshold in Exercise Physiology.
Med Sci Sports Exerc,
48(11), 2320-2334.
Abstract:
Critical Power: an Important Fatigue Threshold in Exercise Physiology.
: the hyperbolic form of the power-duration relationship is rigorous and highly conserved across species, forms of exercise, and individual muscles/muscle groups. For modalities such as cycling, the relationship resolves to two parameters, the asymptote for power (critical power [CP]) and the so-called W' (work doable above CP), which together predict the tolerable duration of exercise above CP. Crucially, the CP concept integrates sentinel physiological profiles-respiratory, metabolic, and contractile-within a coherent framework that has great scientific and practical utility. Rather than calibrating equivalent exercise intensities relative to metabolically distant parameters such as the lactate threshold or V˙O2max, setting the exercise intensity relative to CP unifies the profile of systemic and intramuscular responses and, if greater than CP, predicts the tolerable duration of exercise until W' is expended, V˙O2max is attained, and intolerance is manifested. CP may be regarded as a "fatigue threshold" in the sense that it separates exercise intensity domains within which the physiological responses to exercise can (CP) be stabilized. The CP concept therefore enables important insights into 1) the principal loci of fatigue development (central vs. peripheral) at different intensities of exercise and 2) mechanisms of cardiovascular and metabolic control and their modulation by factors such as O2 delivery. Practically, the CP concept has great potential application in optimizing athletic training programs and performance as well as improving the life quality for individuals enduring chronic disease.
Abstract.
Author URL.
McDonagh STJ, Vanhatalo A, Fulford J, Wylie LJ, Bailey SJ, Jones AM (2016). Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donation.
Am J Physiol Heart Circ Physiol,
311(6), H1520-H1529.
Abstract:
Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donation.
We tested the hypothesis that dietary nitrate (NO3-)-rich beetroot juice (BR) supplementation could partially offset deteriorations in O2 transport and utilization and exercise tolerance after blood donation. Twenty-two healthy volunteers performed moderate-intensity and ramp incremental cycle exercise tests prior to and following withdrawal of ∼450 ml of whole blood. Before donation, all subjects consumed seven 70-ml shots of NO3--depleted BR [placebo (PL)] in the 48 h preceding the exercise tests. During the 48 h after blood donation, subjects consumed seven shots of BR (each containing 6.2 mmol of NO3-, n = 11) or PL (n = 11) before repeating the exercise tests. Hemoglobin concentration and hematocrit were reduced by ∼8-9% following blood donation (P < 0.05), with no difference between the BR and PL groups. Steady-state O2 uptake during moderate-intensity exercise was ∼4% lower after than before donation in the BR group (P < 0.05) but was unchanged in the PL group. The ramp test peak power decreased from predonation (341 ± 70 and 331 ± 68 W in PL and BR, respectively) to postdonation (324 ± 69 and 322 ± 66 W in PL and BR, respectively) in both groups (P < 0.05). However, the decrement in performance was significantly less in the BR than PL group (2.7% vs. 5.0%, P < 0.05). NO3- supplementation reduced the O2 cost of moderate-intensity exercise and attenuated the decline in ramp incremental exercise performance following blood donation. These results have implications for improving functional capacity following blood loss.
Abstract.
Author URL.
Thompson C, Vanhatalo A, Jell H, Fulford J, Carter J, Nyman L, Bailey SJ, Jones AM (2016). Dietary nitrate supplementation improves sprint and high-intensity intermittent running performance. Nitric Oxide: Biology and Chemistry, 61, 55-61.
Wylie LJ, Ortiz de Zevallos J, Isidore T, Nyman L, Vanhatalo A, Bailey SJ, Jones AM (2016). Dose-dependent effects of dietary nitrate on the oxygen cost of moderate-intensity exercise: Acute vs. chronic supplementation.
Nitric Oxide,
57, 30-39.
Abstract:
Dose-dependent effects of dietary nitrate on the oxygen cost of moderate-intensity exercise: Acute vs. chronic supplementation.
PURPOSE: to investigate whether chronic supplementation with a low or moderate dose of dietary nitrate (NO3(-)) reduces submaximal exercise oxygen uptake (V˙O2) and to assess whether or not this is dependent on acute NO3(-) administration prior to exercise. METHODS: Following baseline tests, 34 healthy subjects were allocated to receive 3 mmol NO3(-), 6 mmol NO3(-) or placebo. Two hours following the first ingestion, and after 7, 28 and 30 days of supplementation, subjects completed two moderate-intensity step exercise tests. On days 28 and 30, subjects in the NO3(-) groups completed the test 2 h post consumption of a NO3(-) dose (CHR + ACU) and a placebo dose (CHR). RESULTS: Plasma nitrite concentration ([NO2(-)]) was elevated in a dose-dependent manner at 2 h, 7 days and 28-30 days on the CHR + ACU visit. Compared to pre-treatment baseline, 6 mmol NO3(-) reduced the steady-state V˙O2 during moderate-intensity exercise by 3% at 2 h (P = 0.06), 7 days and at 28-30 days (both P
Abstract.
Author URL.
Jones AM, Ferguson SK, Bailey SJ, Vanhatalo A, Poole DC (2016). Fiber Type-Specific Effects of Dietary Nitrate.
Exerc Sport Sci Rev,
44(2), 53-60.
Abstract:
Fiber Type-Specific Effects of Dietary Nitrate.
Dietary nitrate supplementation increases circulating nitrite concentration, and the subsequent reduction of nitrite to nitric oxide is promoted in hypoxic environments. Given that PO2 is lower in Type II compared with Type I muscle, this article examines the hypothesis that the ergogenicity of nitrate supplementation is linked to specific effects on vascular, metabolic, and contractile function in Type II muscle.
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Author URL.
Wylie LJ, Bailey SJ, Kelly J, Blackwell JR, Vanhatalo A, Jones AM (2016). Influence of beetroot juice supplementation on intermittent exercise performance.
Eur J Appl Physiol,
116(2), 415-425.
Abstract:
Influence of beetroot juice supplementation on intermittent exercise performance.
PURPOSE: This study tested the hypothesis that nitrate (NO3-) supplementation would improve performance during high-intensity intermittent exercise featuring different work and recovery intervals. METHOD: Ten male team-sport players completed high-intensity intermittent cycling tests during separate 5-day supplementation periods with NO3 (-)-rich beetroot juice (BR; 8.2 mmol NO3- day(-1)) and NO3 (-)-depleted beetroot juice (PL; 0.08 mmol NO3- day(-1)). Subjects completed: twenty-four 6-s all-out sprints interspersed with 24 s of recovery (24 × 6-s); seven 30-s all-out sprints interspersed with 240 s of recovery (7 × 30-s); and six 60-s self-paced maximal efforts interspersed with 60 s of recovery (6 × 60-s); on days 3, 4, and 5 of supplementation, respectively. RESULT: Plasma [NO2-] was 237% greater in the BR trials. Mean power output was significantly greater with BR relative to PL in the 24 × 6-s protocol (568 ± 136 vs. 539 ± 136 W; P < 0.05), but not during the 7 × 30-s (558 ± 95 vs. 562 ± 94 W) or 6 × 60-s (374 ± 57 vs. 375 ± 59 W) protocols (P > 0.05). The increase in blood [lactate] across the 24 × 6-s and 7 × 30-s protocols was greater with BR (P < 0.05), but was not different in the 6 × 60-s protocol (P > 0.05). CONCLUSION: BR might be ergogenic during repeated bouts of short-duration maximal-intensity exercise interspersed with short recovery periods, but not necessarily during longer duration intervals or when a longer recovery duration is applied. These findings suggest that BR might have implications for performance enhancement during some types of intermittent exercise.
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Author URL.
Fulford J, Vanhatalo A (2016). Reliability of arterial spin labelling measurements of perfusion within the quadriceps during steady-state exercise.
European Journal of Sport Science,
16(1), 80-87.
Abstract:
Reliability of arterial spin labelling measurements of perfusion within the quadriceps during steady-state exercise
Arterial spin labelling (ASL) provides a potential method to non-invasively determine muscle blood flow and examine the impact of interventions such as supplementation and training. However, it's a method with intrinsically low signal, leading to limitations in accuracy and temporal resolution. To examine these limitations, the current study measured perfusion via ASL on three occasions in the rectus femoris of 10 healthy adults, during light and moderate exercise, over three different exercise durations. For data sampled over 9 min, light intensity exercise gave an average perfusion of 35.0 ± 5.1 ml/min.100g−1 with a coefficient of variation (COV) of 16% and single intraclass correlation coefficient (ICC) of 0.67. For the moderate bout, perfusion was 51.3 ± 5.6 ml/min.100g−1 (COV 10%, ICC 0.82). When the same data were analyzed over 5 min 24 s, perfusion was 37.8 ± 11.13 (COV 30%, ICC 0.13) during light and 49.5 ± 8.8 ml/min.100g−1 (COV 18%, ICC 0.52) during moderate exercise. When sampling was reduced to 1 min 48 s, perfusion was 41.2 ± 13.7 (COV 33%, ICC 0.26) during light and 49.5 ± 13.6 ml/min.100g−1 (COV 28%, ICC 0.04) during moderate exercise. For 9 min a significant perfusion difference was found between the exercise intensities; however, this was not the case for sampling over 5 min 24 s or 1 min 48 s. Such findings illustrate the potential of ASL to non-invasively monitor muscle perfusion under steady-state conditions, but highlight that extended exercise protocols are necessary in order to generate date of sufficient reliability to be able to discriminate intervention dependent perfusion differences.
Abstract.
Black MI, Jones AM, Kelly JA, Bailey SJ, Vanhatalo A (2016). The constant work rate critical power protocol overestimates ramp incremental exercise performance.
Eur J Appl Physiol,
116(11-12), 2415-2422.
Abstract:
The constant work rate critical power protocol overestimates ramp incremental exercise performance.
PURPOSE: the parameters of the power-duration relationship (i.e. the critical power, CP, and the curvature constant, W') may theoretically predict maximal performance capability for exercise above the CP. The CP and W' are associated with the parameters of oxygen uptake ([Formula: see text]O2) kinetics, which can be altered by manipulation of the work-rate forcing function. We tested the hypothesis that the CP and W' derived from constant work-rate (CWR) prediction trials would overestimate ramp incremental exercise performance. METHODS: Thirty subjects (males, n = 28; females, n = 2) performed a ramp incremental test, and 3-5 CWR prediction trials for the determination of the CP and W'. Multiple ramp incremental tests and corresponding CP and W' estimates were available for some subjects such that in total 51 ramp test performances were predicted. RESULTS: the ramp incremental test performance (729 ± 113 s) was overestimated by the CP and W' estimates derived from the best (751 ± 114 s, P
Abstract.
Author URL.
Vanhatalo A, Black MI, DiMenna FJ, Blackwell JR, Schmidt JF, Thompson C, Wylie LJ, Mohr M, Bangsbo J, Krustrup P, et al (2016). The mechanistic bases of the power-time relationship: muscle metabolic responses and relationships to muscle fibre type.
Journal of PhysiologyAbstract:
The mechanistic bases of the power-time relationship: muscle metabolic responses and relationships to muscle fibre type
We hypothesised that: 1) the critical power (CP) will represent a boundary separating steady state from non-steady state muscle metabolic responses during whole-body exercise and 2) that the CP and the W′ (curvature constant of the power-time relationship for high-intensity exercise) will be correlated with type I and type IIx muscle fibre distributions, respectively. Four men and four women performed a 3-min all-out cycling test for the estimation of CP and constant work rate (CWR) tests slightly >CP until exhaustion (Tlim), slightly CP Tlim isotime to test hypothesis 1. Eleven men performed 3-min all-out tests and donated muscle biopsies to test hypothesis 2. Below CP, muscle [PCr] (42.6±7.1 vs 49.4±6.9 mmol/kgDW), [La-] (34.8±12.6 vs 35.5±13.2 mmol/kgDW) and pH (7.11±0.08 vs 7.10±0.11) remained stable between ~12 and 24 min (P>0.05 for all), whereas these variables changed with time >CP such that they were greater ([La-] 95.6±14.1 mmol/kgDW) and lower ([PCr] 24.2±3.9 mmol/kgDW; pH 6.84±0.06) (P
Abstract.
Bailey SJ, Blackwell JR, Williams E, Wylie LJ, Vanhatalo A, Winyard PG, Jones AM (2016). Two weeks of watermelon juice supplementation improves nitric oxide bioavailability but not endurance exercise performance in humans. Nitric Oxide, 59, 10-20.
2015
Ashworth A, Bailey SJ, Hayward GM, DiMenna F, Vanhatalo A, Jones AM (2015). Dietary nitrate - an unrecognized nutrient?.
Clin Nutr ESPEN,
10(5).
Author URL.
Thompson C, Wylie LJ, Fulford J, Kelly J, Black MI, McDonagh STJ, Jeukendrup AE, Vanhatalo A, Jones AM (2015). Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise.
Eur J Appl Physiol,
115(9), 1825-1834.
Abstract:
Dietary nitrate improves sprint performance and cognitive function during prolonged intermittent exercise.
UNLABELLED: it is possible that dietary nitrate (NO3 (-)) supplementation may improve both physical and cognitive performance via its influence on blood flow and cellular energetics. PURPOSE: to investigate the effects of dietary NO3 (-) supplementation on exercise performance and cognitive function during a prolonged intermittent sprint test (IST) protocol, which was designed to reflect typical work patterns during team sports. METHODS: in a double-blind randomised crossover study, 16 male team-sport players received NO3 (-)-rich (BR; 140 mL day(-1); 12.8 mmol of NO3 (-)), and NO3 (-)-depleted (PL; 140 mL day(-1); 0.08 mmol NO3 (-)) beetroot juice for 7 days. On day 7 of supplementation, subjects completed the IST (two 40-min "halves" of repeated 2-min blocks consisting of a 6-s "all-out" sprint, 100-s active recovery and 20 s of rest), on a cycle ergometer during which cognitive tasks were simultaneously performed. RESULTS: Total work done during the sprints of the IST was greater in BR (123 ± 19 kJ) compared to PL (119 ± 17 kJ; P < 0.05). Reaction time of response to the cognitive tasks in the second half of the IST was improved in BR compared to PL (BR first half: 820 ± 96 vs. second half: 817 ± 86 ms; PL first half: 824 ± 114 vs. second half: 847 ± 118 ms; P < 0.05). There was no difference in response accuracy. CONCLUSIONS: These findings suggest that dietary NO3 (-) enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise.
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Author URL.
Ashworth A, Mitchell K, Blackwell JR, Vanhatalo A, Jones AM (2015). High-nitrate vegetable diet increases plasma nitrate and nitrite concentrations and reduces blood pressure in healthy women.
Public Health Nutr,
18(14), 2669-2678.
Abstract:
High-nitrate vegetable diet increases plasma nitrate and nitrite concentrations and reduces blood pressure in healthy women.
OBJECTIVE: Epidemiological studies suggest that green leafy vegetables, which are high in dietary nitrate, are protective against CVD such as stroke. High blood pressure (BP) is a major risk factor for stroke and inorganic nitrate has been shown to reduce BP. The objective of the present study was to test the hypothesis that diets containing high-nitrate (HN) vegetables would increase plasma nitrate and nitrite concentrations and reduce BP in healthy women. DESIGN: a randomized, crossover trial, where participants received HN vegetables (HN diet) or avoided HN vegetables (Control diet) for 1 week. Before and after each intervention, resting BP and plasma nitrate and nitrite concentrations were measured. SETTING: University of Exeter, UK. SUBJECTS: Nineteen healthy women (mean age 20 (sd 2) years; mean BMI 22·5 (sd 3·8) kg/m2). RESULTS: the HN diet significantly increased plasma nitrate concentration (before HN diet: mean 24·4 (sd 5·6) µmol/l; after HN diet: mean 61·0 (sd 44·1) µmol/l, P
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Author URL.
Simpson LP, Jones AM, Skiba PF, Vanhatalo A, Wilkerson D (2015). Influence of hypoxia on the power-duration relationship during high-intensity exercise.
Int J Sports Med,
36(2), 113-119.
Abstract:
Influence of hypoxia on the power-duration relationship during high-intensity exercise.
We investigated the influence of hypoxia on the asymptote (critical power, CP) and the curvature constant (W') of the hyperbolic power-duration relationship, as measured by both conventional and all-out testing procedures. 13 females completed 5 constant-power prediction trials and a 3-min all-out test to estimate CP and W', in both normoxia (N) and moderate hypoxia (H; FiO2=0.13). CP was significantly reduced in hypoxia compared to normoxia when estimated by conventional (H:132±17 vs. N:175±25 W; P
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Author URL.
Skiba PF, Fulford J, Clarke DC, Vanhatalo A, Jones AM (2015). Intramuscular determinants of the ability to recover work capacity above critical power.
European Journal of Applied Physiology,
115(4), 703-713.
Abstract:
Intramuscular determinants of the ability to recover work capacity above critical power
Purpose: the primary purpose of this investigation was to compare the recovery of the W′ to the recovery of intramuscular substrates and metabolites using 31P- and 1H-magnetic resonance spectroscopy. Methods: Ten healthy recreationally trained subjects were tested to determine critical power (CP) and W′ for single-leg-extensor exercise. They subsequently exercised in the bore of a 1.5-T MRI scanner at a supra-CP work rate. Following exhaustion, the subjects rested in place for 1, 2, 5 or 7 min, and then repeated the effort. The temporal course of W′ recovery was estimated, which was then compared to the recovery of creatine phosphate [PCr], pH, carnosine content, and to the output of a novel derivation of the W′BAL model. Results: W′ recovery closely correlated with the predictions of the novel model (r = 0.97, p = 0.03). [PCr] recovered faster (Formula presented.) than W′(Formula presented.) the W′ available for the second exercise bout was directly correlated with the difference between [PCr] at the beginning of the work bout and [PCr] at exhaustion (r = 0.99, p = 0.005). Nonlinear regression revealed an inverse curvilinear relationship between carnosine concentration and the W′t1/2 (r2 = 0.55). Conclusion: the kinetics of W′ recovery in single-leg-extensor exercise is comparable to that observed in whole-body exercise, suggesting a conserved mechanism. The extent to which the recovery of the W′ can be directly attributed to the recovery of [PCr] is unclear. The relationship of the W′ to muscle carnosine content suggests novel future avenues of investigation.
Abstract.
Black MI, Jones AM, Bailey SJ, Vanhatalo A (2015). Self-pacing increases critical power and improves performance during severe-intensity exercise.
Appl Physiol Nutr Metab,
40(7), 662-670.
Abstract:
Self-pacing increases critical power and improves performance during severe-intensity exercise.
The parameters of the power-duration relationship for severe-intensity exercise (i.e. the critical power (CP) and the curvature constant (W')) are related to the kinetics of pulmonary O2 uptake, which may be altered by pacing strategy. We tested the hypothesis that the CP would be higher when derived from a series of self-paced time-trials (TT) than when derived from the conventional series of constant work-rate (CWR) exercise tests. Ten male subjects (age, 21.5 ± 1.9 years; mass, 75.2 ± 11.5 kg) completed 3-4 CWR and 3-4 TT prediction trial protocols on a cycle ergometer for the determination of the CP and W'. The CP derived from the TT protocol (265 ± 44 W) was greater (P < 0.05) than the CP derived from the CWR protocol (250 ± 47 W), while the W' was not different between protocols (TT: 18.1 ± 5.7 kJ, CWR: 20.6 ± 7.4 kJ, P > 0.05). The mean response time of pulmonary O2 uptake was shorter during the TTs than the CWR trials (TT: 34 ± 16, CWR: 39 ± 19 s, P < 0.05). The CP was correlated with the total O2 consumed in the first 60 s across both protocols (r = 0.88, P < 0.05, n = 20). These results suggest that in comparison with the conventional CWR exercise protocol, a self-selected pacing strategy enhances CP and improves severe-intensity exercise performance. The greater CP during TT compared with CWR exercise has important implications for performance prediction, suggesting that TT completion times may be overestimated by CP and W' parameters derived from CWR protocols.
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McDonagh STJ, Wylie LJ, Winyard PG, Vanhatalo A, Jones AM (2015). The Effects of Chronic Nitrate Supplementation and the Use of Strong and Weak Antibacterial Agents on Plasma Nitrite Concentration and Exercise Blood Pressure.
Int J Sports Med,
36(14), 1177-1185.
Abstract:
The Effects of Chronic Nitrate Supplementation and the Use of Strong and Weak Antibacterial Agents on Plasma Nitrite Concentration and Exercise Blood Pressure.
Chlorhexidine-containing mouthwash (STRONG), which disturbs oral microflora, has been shown to diminish the rise in plasma nitrite concentration ([NO2-]) and attenuate the reduction in resting blood pressure (BP) typically seen after acute nitrate (NO3-) ingestion. We aimed to determine whether STRONG and weaker antiseptic agents attenuate the physiological effects of chronic NO3- supplementation using beetroot juice (BR). 12 healthy volunteers mouth-rinsed with STRONG, non-chlorhexidine mouthwash (WEAK) and deionised water (CON) 3 times a day, and ingested 70 mL BR (6.2 mmol NO3-), twice a day, for 6 days. BP (at rest and during 10 min of treadmill walking) and plasma and salivary [NO3-] and [NO2-] were measured prior to and on day 6 of supplementation. The change in salivary [NO3-] 4 h post final ingestion was higher (P
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Author URL.
Bailey SJ, Blackwell JR, Lord T, Vanhatalo A, Winyard PG, Jones AM (2015). l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans.
J Appl Physiol (1985),
119(4), 385-395.
Abstract:
l-Citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans.
The purpose of this study was to compare the effects of l-citrulline (Cit) and l-arginine (Arg) supplementation on nitric oxide (NO) biomarkers, pulmonary O2 uptake (V̇o2) kinetics, and exercise performance. In a randomized, placebo (Pla)-controlled, crossover study, 10 healthy adult men completed moderate- and severe-intensity cycling exercise on days 6 and 7 of a 7-day supplementation period with Pla, Arg (6 g/day), and Cit (6 g/day). Compared with Pla, plasma Arg concentration was increased by a similar magnitude with Arg and Cit supplementation, but plasma Cit concentration was only increased (P < 0.001) with Cit supplementation. Plasma nitrite (NO2 (-)) concentration was increased with Arg supplementation (P < 0.05) and tended to increase with Cit supplementation (P = 0.08) compared with Pla (83 ± 25, 106 ± 41, and 100 ± 38 nM with Pla, Arg, and Cit, respectively); however, mean arterial blood pressure was only lower (P < 0.05) after Cit supplementation. The steady-state V̇o2 amplitude during moderate-intensity cycle exercise was not significantly different between supplements, but Cit lowered the V̇o2 mean response time (59 ± 8 and 53 ± 5 s with Pla and Cit, respectively, P < 0.05) during severe-intensity exercise, improved tolerance to severe-intensity exercise (589 ± 101 and 661 ± 107 s with Pla and Cit, respectively), and increased the total amount of work completed in the exercise performance test (123 ± 18 and 125 ± 19 kJ with Pla and Cit, respectively, P < 0.05). These variables were not altered by Arg supplementation (P > 0.05). In conclusion, these results suggest that short-term Cit, but not Arg, supplementation can improve blood pressure, V̇o2 kinetics, and exercise performance in healthy adults.
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Author URL.
2014
Black MI, Durant J, Jones AM, Vanhatalo A (2014). Critical power derived from a 3-min all-out test predicts 16.1-km road time-trial performance.
European Journal of Sport Science,
14(3), 217-223.
Abstract:
Critical power derived from a 3-min all-out test predicts 16.1-km road time-trial performance
It has been shown that the critical power (CP) in cycling estimated using a novel 3-min all-out protocol is reliable and closely matches the CP derived from conventional procedures. The purpose of this study was to assess the predictive validity of the all-out test CP estimate. We hypothesised that the all-out test CP would be significantly correlated with 16.1-km road time-trial (TT) performance and more strongly correlated with performance than the gas exchange threshold (GET), respiratory compensation point (RCP) and V̇O2 max. Ten club-level male cyclists (mean±SD: age 33.8±8.2 y, body mass 73.8±4.3 kg, V̇O2 max 60±4 ml·kg-1·min-1) performed a 10-mile road TT, a ramp incremental test to exhaustion, and two 3-min all-out tests, the first of which served as familiarisation. The 16.1-km TT performance (27.1±1.2 min) was significantly correlated with the CP (309±34 W; r=-0.83, P
Abstract.
Vanhatalo A, Jones AM, Blackwell JR, Winyard PG, Fulford J (2014). Dietary nitrate accelerates postexercise muscle metabolic recovery and O2 delivery in hypoxia.
J Appl Physiol (1985),
117(12), 1460-1470.
Abstract:
Dietary nitrate accelerates postexercise muscle metabolic recovery and O2 delivery in hypoxia.
We tested the hypothesis that the time constants (τ) of postexercise T2. MRI signal intensity (an index of O2 delivery) and muscle [PCr] (an index of metabolic perturbation, measured by (31)P-MRS) in hypoxia would be accelerated after dietary nitrate (NO3 (-)) supplementation. In a double-blind crossover design, eight moderately trained subjects underwent 5 days of NO3 (-) (beetroot juice, BR; 8.2 mmol/day NO3 (-)) and placebo (PL; 0.003 mmol/day NO3 (-)) supplementation in four conditions: normoxic PL (N-PL), hypoxic PL (H-PL; 13% O2), normoxic NO3 (-) (N-BR), and hypoxic NO3 (-) (H-BR). The single-leg knee-extension protocol consisted of 10 min of steady-state exercise and 24 s of high-intensity exercise. The [PCr] recovery τ was greater in H-PL (30 ± 4 s) than H-BR (22 ± 4 s), N-PL (24 ± 4 s) and N-BR (22 ± 4 s) (P < 0.05) and the maximal rate of mitochondrial ATP resynthesis (Qmax) was lower in the H-PL (1.12 ± 0.16 mM/s) compared with H-BR (1.35 ± 0.26 mM/s), N-PL (1.47 ± 0.28 mM/s), and N-BR (1.40 ± 0.21 mM/s) (P < 0.05). The τ of postexercise T2. signal intensity was greater in H-PL (47 ± 14 s) than H-BR (32 ± 10 s), N-PL (38 ± 9 s), and N-BR (27 ± 6 s) (P < 0.05). The postexercise [PCr] and T2. recovery τ were correlated in hypoxia (r = 0.60; P < 0.05), but not in normoxia (r = 0.28; P > 0.05). These findings suggest that the NO3 (-)-NO2 (-)-NO pathway is a significant modulator of muscle energetics and O2 delivery during hypoxic exercise and subsequent recovery.
Abstract.
Author URL.
Kelly J, Vanhatalo A, Bailey SJ, Wylie LJ, Tucker C, List S, Winyard PG, Jones AM (2014). Dietary nitrate supplementation: effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia.
Am J Physiol Regul Integr Comp Physiol,
307(7), R920-R930.
Abstract:
Dietary nitrate supplementation: effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia.
We investigated the effects of dietary nitrate (NO3 (-)) supplementation on the concentration of plasma nitrite ([NO2 (-)]), oxygen uptake (V̇o2) kinetics, and exercise tolerance in normoxia (N) and hypoxia (H). In a double-blind, crossover study, 12 healthy subjects completed cycle exercise tests, twice in N (20.9% O2) and twice in H (13.1% O2). Subjects ingested either 140 ml/day of NO3 (-)-rich beetroot juice (8.4 mmol NO3; BR) or NO3 (-)-depleted beetroot juice (PL) for 3 days prior to moderate-intensity and severe-intensity exercise tests in H and N. Preexercise plasma [NO2 (-)] was significantly elevated in H-BR and N-BR compared with H-PL (P < 0.01) and N-PL (P < 0.01). The rate of decline in plasma [NO2 (-)] was greater during severe-intensity exercise in H-BR [-30 ± 22 nM/min, 95% confidence interval (CI); -44, -16] compared with H-PL (-7 ± 10 nM/min, 95% CI; -13, -1; P < 0.01) and in N-BR (-26 ± 19 nM/min, 95% CI; -38, -14) compared with N-PL (-1 ± 6 nM/min, 95% CI; -5, 2; P < 0.01). During moderate-intensity exercise, steady-state pulmonary V̇o2 was lower in H-BR (1.91 ± 0.28 l/min, 95% CI; 1.77, 2.13) compared with H-PL (2.05 ± 0.25 l/min, 95% CI; 1.93, 2.26; P = 0.02), and V̇o2 kinetics was faster in H-BR (τ: 24 ± 13 s, 95% CI; 15, 32) compared with H-PL (31 ± 11 s, 95% CI; 23, 38; P = 0.04). NO3 (-) supplementation had no significant effect on V̇o2 kinetics during severe-intensity exercise in hypoxia, or during moderate-intensity or severe-intensity exercise in normoxia. Tolerance to severe-intensity exercise was improved by NO3 (-) in hypoxia (H-PL: 197 ± 28; 95% CI; 173, 220 vs. H-BR: 214 ± 43 s, 95% CI; 177, 249; P = 0.04) but not normoxia. The metabolism of NO2 (-) during exercise is altered by NO3 (-) supplementation, exercise, and to a lesser extent, hypoxia. In hypoxia, NO3 (-) supplementation enhances V̇o2 kinetics during moderate-intensity exercise and improves severe-intensity exercise tolerance. These findings may have important implications for individuals exercising at altitude.
Abstract.
Author URL.
Skiba PF, Jackman S, Clarke D, Vanhatalo A, Jones AM (2014). Effect of work and recovery durations on W′ reconstitution during intermittent exercise.
Medicine and Science in Sports and Exercise,
46(7), 1433-1440.
Abstract:
Effect of work and recovery durations on W′ reconstitution during intermittent exercise
Purpose: We recently presented an integrating model of the curvature constant of the hyperbolic power-time relationship (W′) that permits the calculation of the W′ balance (W′BAL) remaining at any time during intermittent exercise. Although a relationship between recovery power and the rate of W′ recovery was demonstrated, the effect of the length of work or recovery intervals remains unclear. Methods: After determining V̇O2max, critical power, and W′, 11 subjects completed six separate exercise tests on a cycle ergometer on different days, and in random order. Tests consisted of a period of intermittent severe-intensity exercise until the subject depleted approximately 50% of their predicted W′BAL, followed by a constant work rate (CWR) exercise bout until exhaustion. Work rates were kept constant between trials; however, either work or recovery durations during intermittent exercise were varied. The actual W′ measured during the CWR (W′ACT) was compared with the amount of W′ predicted to be available by the W′BAL model. Results: Although some differences between W′BAL and W′ACT were noted, these amounted to only-1.6 ± 1.1 kJ when averaged across all conditions. The W′ACT was linearly correlated with the difference between V̇O2 at the start of CWR and V̇O2max (r = 0.79, P < 0.01). Conclusions: the W′BAL model provided a generally robust prediction of CWR W′. There may exist a physiological optimum formulation of work and recovery intervals such that baseline V̇O2 can be minimized, leading to an enhancement of subsequent exercise tolerance. These results may have important implications for athletic training and racing. © 2014 by the American College of Sports Medicine.
Abstract.
Skiba PF, Clarke D, Vanhatalo A, Jones AM (2014). Validation of a novel intermittent w' model for cycling using field data.
Int J Sports Physiol Perform,
9(6), 900-904.
Abstract:
Validation of a novel intermittent w' model for cycling using field data.
Recently, an adaptation to the critical-power (CP) model was published, which permits the calculation of the balance of the work capacity available above the CP remaining (W'bal) at any time during intermittent exercise. As the model is now in use in both amateur and elite sport, the purpose of this investigation was to assess the validity of the W'bal model in the field. Data were collected from the bicycle power meters of 8 trained triathletes. W'bal was calculated and compared between files where subjects reported becoming prematurely exhausted during training or competition and files where the athletes successfully completed a difficult assigned task or race without becoming exhausted. Calculated W'bal was significantly different between the 2 conditions (P <. 0001). The mean W'bal at exhaustion was 0.5 ± 1.3 kJ (95% CI = 0-0.9 kJ), whereas the minimum W'bal in the nonexhausted condition was 3.6 ± 2.0 kJ (95% CI = 2.1-4.0 kJ). Receiver-operator-characteristic (ROC) curve analysis indicated that the W'bal model is useful for identifying the point at which athletes are in danger of becoming exhausted (area under the ROC curve =. 914, SE. 05, 95% CI. 82-1.0, P <. 0001). The W'bal model may therefore represent a useful new development in assessing athlete fatigue state during training and racing.
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Author URL.
2013
Chidnok W, Dimenna FJ, Bailey SJ, Burnley M, Wilkerson DP, Vanhatalo A, Jones AM (2013).VO2max is not altered by self-pacing during incremental exercise.
Eur J Appl Physiol,
113(2), 529-539.
Abstract:
.VO2max is not altered by self-pacing during incremental exercise.
We tested the hypothesis that incremental cycling to exhaustion that is paced using clamps of the rating of perceived exertion (RPE) elicits higher. VO2max values compared to a conventional ramp incremental protocol when test duration is matched. Seven males completed three incremental tests to exhaustion to measure. VO2max. The incremental protocols were of similar duration and included: a ramp test at 30 W min(-1) with constant cadence (RAMP1); a ramp test at 30 W min(-1) with cadence free to fluctuate according to subject preference (RAMP2); and a self-paced incremental test in which the power output was selected by the subject according to prescribed increments in RPE (SPT). The subjects also completed a. VO2max 'verification' test at a fixed high-intensity power output and a 3-min all-out test. No difference was found for. VO2max between the incremental protocols (RAMP1 = 4.33 ± 0.60 L min(-1); RAMP2 = 4.31 ± 0.62 L min(-1); SPT = 4.36 ± 0.59 L min(-1); P > 0.05) nor between the incremental protocols and the peak.VO2max measured during the 3-min all-out test (4.33 ± 0.68 L min(-1)) or the. VO2max measured in the verification test (4.32 ± 0.69 L min(-1)). The integrated electromyogram, blood lactate concentration, heart rate and minute ventilation at exhaustion were not different (P > 0.05) between the incremental protocols. In conclusion, when test duration is matched, SPT does not elicit a higher. VO2max compared to conventional incremental protocols. The striking similarity of. VO2max measured across an array of exercise protocols indicates that there are physiological limits to the attainment of. VO2max that cannot be exceeded by self-pacing.
Abstract.
Author URL.
Wylie LJ, Kelly J, Bailey SJ, Blackwell JR, Skiba PF, Winyard PG, Jeukendrup AE, Vanhatalo A, Jones AM (2013). Beetroot juice and exercise: pharmacodynamic and dose-response relationships.
J Appl Physiol (1985),
115(3), 325-336.
Abstract:
Beetroot juice and exercise: pharmacodynamic and dose-response relationships.
Dietary supplementation with beetroot juice (BR), containing approximately 5-8 mmol inorganic nitrate (NO3(-)), increases plasma nitrite concentration ([NO2(-)]), reduces blood pressure, and may positively influence the physiological responses to exercise. However, the dose-response relationship between the volume of BR ingested and the physiological effects invoked has not been investigated. In a balanced crossover design, 10 healthy men ingested 70, 140, or 280 ml concentrated BR (containing 4.2, 8.4, and 16.8 mmol NO3(-), respectively) or no supplement to establish the effects of BR on resting plasma [NO3(-)] and [NO2(-)] over 24 h. Subsequently, on six separate occasions, 10 subjects completed moderate-intensity and severe-intensity cycle exercise tests, 2.5 h postingestion of 70, 140, and 280 ml BR or NO3(-)-depleted BR as placebo (PL). Following acute BR ingestion, plasma [NO2(-)] increased in a dose-dependent manner, with the peak changes occurring at approximately 2-3 h. Compared with PL, 70 ml BR did not alter the physiological responses to exercise. However, 140 and 280 ml BR reduced the steady-state oxygen (O2) uptake during moderate-intensity exercise by 1.7% (P = 0.06) and 3.0% (P < 0.05), whereas time-to-task failure was extended by 14% and 12% (both P < 0.05), respectively, compared with PL. The results indicate that whereas plasma [NO2(-)] and the O2 cost of moderate-intensity exercise are altered dose dependently with NO3(-)-rich BR, there is no additional improvement in exercise tolerance after ingesting BR containing 16.8 compared with 8.4 mmol NO3(-). These findings have important implications for the use of BR to enhance cardiovascular health and exercise performance in young adults.
Abstract.
Author URL.
Wylie LJ, Mohr M, Krustrup P, Jackman SR, Ermιdis G, Kelly J, Black MI, Bailey SJ, Vanhatalo A, Jones AM, et al (2013). Dietary nitrate supplementation improves team sport-specific intense intermittent exercise performance.
Eur J Appl Physiol,
113(7), 1673-1684.
Abstract:
Dietary nitrate supplementation improves team sport-specific intense intermittent exercise performance.
Recent studies have suggested that dietary inorganic nitrate (NO₃(-)) supplementation may improve muscle efficiency and endurance exercise tolerance but possible effects during team sport-specific intense intermittent exercise have not been examined. We hypothesized that NO₃(-) supplementation would enhance high-intensity intermittent exercise performance. Fourteen male recreational team-sport players were assigned in a double-blind, randomized, crossover design to consume 490 mL of concentrated, nitrate-rich beetroot juice (BR) and nitrate-depleted placebo juice (PL) over ~30 h preceding the completion of a Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1). Resting plasma nitrite concentration ([NO₂(-)]) was ~400% greater in BR compared to PL. Plasma [NO₂(-)] declined by 20% in PL (P < 0.05) and by 54 % in BR (P < 0.05) from pre-exercise to end-exercise. Performance in the Yo-Yo IR1 was 4.2% greater (P < 0.05) with BR (1,704 ± 304 m) compared to PL (1,636 ± 288 m). Blood [lactate] was not different between BR and PL, but the mean blood [glucose] was lower (3.8 ± 0.8 vs. 4.2 ± 1.1 mM, P < 0.05) and the rise in plasma [K(+)] tended to be reduced in BR compared to PL (P = 0.08). These findings suggest that NO₃(-) supplementation may promote NO production via the nitrate-nitrite-NO pathway and enhance Yo-Yo IR1 test performance, perhaps by facilitating greater muscle glucose uptake or by better maintaining muscle excitability. Dietary NO₃(-) supplementation improves performance during intense intermittent exercise and may be a useful ergogenic aid for team sports players.
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Author URL.
Kelly J, Vanhatalo A, Wilkerson DP, Wylie LJ, Jones AM (2013). Effects of nitrate on the power-duration relationship for severe-intensity exercise.
Medicine and Science in Sports and Exercise,
45(9), 1798-1806.
Abstract:
Effects of nitrate on the power-duration relationship for severe-intensity exercise
PURPOSE: the power asymptote (critical power [CP]) and curvature constant (W′) of the power-duration relationship dictate the tolerance to severe-intensity exercise. We tested the hypothesis that dietary nitrate supplementation would increase the CP and/or the W′ during cycling exercise. METHODS: in a double-blind, randomized, crossover study, nine recreationally active male subjects supplemented their diet with either nitrate-rich concentrated beetroot juice (BR; 2 × 250 mL·d, ∼8.2 mmol·d nitrate) or a nitrate-depleted BR placebo (PL; 2 × 250 mL·d, ∼0.006 mmol·d nitrate). In each condition, the subjects completed four separate severe-intensity exercise bouts to exhaustion at 60% of the difference between the gas exchange threshold and the peak power attained during incremental exercise (60% Δ), 70% Δ, 80% Δ, and 100% peak power, and the results were used to establish CP and W′. RESULTS: Nitrate supplementation improved exercise tolerance during exercise at 60% Δ (BR, 696 ± 120 vs PL, 593 ± 68 s; P < 0.05), 70% Δ (BR, 452 ± 106 vs PL, 390 ± 86 s; P < 0.05), and 80% Δ (BR, 294 ± 50 vs PL, 263 ± 50 s; P < 0.05) but not 100% peak power (BR, 182 ± 37 vs PL, 166 ± 26 s; P = 0.10). Neither CP (BR, 221 ± 27 vs PL, 218 ± 26 W) nor W′ (BR, 19.3 ± 4.6 vs PL, 17.8 ± 3 kJ) were significantly altered by BR. CONCLUSION: Dietary nitrate supplementation improved endurance during severe-intensity exercise in recreationally active subjects without significantly increasing either the CP or the W′. Copyright © 2013 by the American College of Sports Medicine.
Abstract.
Kelly J, Vanhatalo A, Wilkerson DP, Wylie LJ, Jones AM (2013). Effects of nitrate on the power-duration relationship for severe-intensity exercise.
Med Sci Sports Exerc,
45(9), 1798-1806.
Abstract:
Effects of nitrate on the power-duration relationship for severe-intensity exercise.
PURPOSE: the power asymptote (critical power [CP]) and curvature constant (W') of the power-duration relationship dictate the tolerance to severe-intensity exercise. We tested the hypothesis that dietary nitrate supplementation would increase the CP and/or the W' during cycling exercise. METHODS: in a double-blind, randomized, crossover study, nine recreationally active male subjects supplemented their diet with either nitrate-rich concentrated beetroot juice (BR; 2 × 250 mL·d, ∼8.2 mmol·d nitrate) or a nitrate-depleted BR placebo (PL; 2 × 250 mL·d, ∼0.006 mmol·d nitrate). In each condition, the subjects completed four separate severe-intensity exercise bouts to exhaustion at 60% of the difference between the gas exchange threshold and the peak power attained during incremental exercise (60% Δ), 70% Δ, 80% Δ, and 100% peak power, and the results were used to establish CP and W'. RESULTS: Nitrate supplementation improved exercise tolerance during exercise at 60% Δ (BR, 696 ± 120 vs PL, 593 ± 68 s; P < 0.05), 70% Δ (BR, 452 ± 106 vs PL, 390 ± 86 s; P < 0.05), and 80% Δ (BR, 294 ± 50 vs PL, 263 ± 50 s; P < 0.05) but not 100% peak power (BR, 182 ± 37 vs PL, 166 ± 26 s; P = 0.10). Neither CP (BR, 221 ± 27 vs PL, 218 ± 26 W) nor W' (BR, 19.3 ± 4.6 vs PL, 17.8 ± 3 kJ) were significantly altered by BR. CONCLUSION: Dietary nitrate supplementation improved endurance during severe-intensity exercise in recreationally active subjects without significantly increasing either the CP or the W'.
Abstract.
Author URL.
Chidnok W, Dimenna FJ, Bailey SJ, Wilkerson DP, Vanhatalo A, Jones AM (2013). Effects of pacing strategy on work done above critical power during high-intensity exercise.
Medicine and Science in Sports and Exercise,
45(7), 1377-1385.
Abstract:
Effects of pacing strategy on work done above critical power during high-intensity exercise
PURPOSE: We investigated the influence of pacing strategy on the work completed above critical power (CP) before exhaustion (W>CP) and the peak V̇O2 attained during high-intensity cycling. METHODS: After the determination of V̇O2max from a ramp incremental cycling (INC) test and the estimation of the parameters of the power-duration relationship for high-intensity exercise (i.e. CP and W′) from a 3-min all-out cycling test (AOT), eight male subjects completed a cycle test to exhaustion at a severe-intensity constant work rate (CWR) estimated to result in exhaustion in 3 min and a self-paced 3-min cycling time trial (SPT). RESULTS: the V̇O 2max determined from INC was 4.24 ± 0.69 L·min -1, and the CP and the W′ estimated from AOT were 260 ± 60 W and 16.5 ± 4.0 kJ, respectively. W>CP during SPT was not significantly different from W>CP during CWR (15.3 ± 5.6 and 16.6 ± 7.4 kJ, respectively), and these values were also similar to W>CP during INC (16.4 ± 4.0 kJ) and W′ estimated from AOT. The peak V̇O2 during SPT was not significantly different from peak V̇O2 during CWR (4.20 ± 0.77 and 4.14 ± 0.75 L·min -1, respectively), and these values were similar to the V̇O 2max determined from INC and the peak V̇O2 during AOT (4.10 ± 0.79 L·min-1). CONCLUSION: Exhaustion during high-intensity exercise coincides with the achievement of the same peak V̇O2 (V̇O2max) and the completion of the same W>CP, irrespective of the work rate forcing function (INC or CWR) or pacing strategy (enforced pace or self-paced). These findings indicate that exhaustion during high-intensity exercise is based on highly predictable physiological processes, which are unaffected when pacing strategy is self-selected. Copyright © 2013 by the American College of Sports Medicine.
Abstract.
Chidnok W, Dimenna FJ, Bailey SJ, Wilkerson DP, Vanhatalo A, Jones AM (2013). Effects of pacing strategy on work done above critical power during high-intensity exercise.
Med Sci Sports Exerc,
45(7), 1377-1385.
Abstract:
Effects of pacing strategy on work done above critical power during high-intensity exercise.
PURPOSE: We investigated the influence of pacing strategy on the work completed above critical power (CP) before exhaustion (W>CP) and the peak V˙O2 attained during high-intensity cycling. METHODS: After the determination of VO(2max) from a ramp incremental cycling (INC) test and the estimation of the parameters of the power-duration relationship for high-intensity exercise (i.e. CP and W') from a 3-min all-out cycling test (AOT), eight male subjects completed a cycle test to exhaustion at a severe-intensity constant work rate (CWR) estimated to result in exhaustion in 3 min and a self-paced 3-min cycling time trial (SPT). RESULTS: the VO(2max) determined from INC was 4.24 ± 0.69 L · min(-1), and the CP and the W' estimated from AOT were 260 ± 60 W and 16.5 ± 4.0 kJ, respectively. W>CP during SPT was not significantly different from W>CP during CWR (15.3 ± 5.6 and 16.6 ± 7.4 kJ, respectively), and these values were also similar to W(>CP) during INC (16.4 ± 4.0 kJ) and W' estimated from AOT. The peak VO(2) during SPT was not significantly different from peak VO(2) during CWR (4.20 ± 0.77 and 4.14 ± 0.75 L · min(-1), respectively), and these values were similar to the VO(2max) determined from INC and the peak VO(2) during AOT (4.10 ± 0.79 L · min(-1)). CONCLUSION: Exhaustion during high-intensity exercise coincides with the achievement of the same peak VO2 (VO(2max)) and the completion of the same W>CP, irrespective of the work rate forcing function (INC or CWR) or pacing strategy (enforced pace or self-paced). These findings indicate that exhaustion during high-intensity exercise is based on highly predictable physiological processes, which are unaffected when pacing strategy is self-selected.
Abstract.
Author URL.
Kelly J, Fulford J, Vanhatalo A, Blackwell JR, French O, Bailey SJ, Gilchrist M, Winyard PG, Jones AM (2013). Effects of short-term dietary nitrate supplementation on blood pressure, O2 uptake kinetics, and muscle and cognitive function in older adults.
Am J Physiol Regul Integr Comp Physiol,
304(2), R73-R83.
Abstract:
Effects of short-term dietary nitrate supplementation on blood pressure, O2 uptake kinetics, and muscle and cognitive function in older adults.
Dietary nitrate (NO(3)(-)) supplementation has been shown to reduce resting blood pressure and alter the physiological response to exercise in young adults. We investigated whether these effects might also be evident in older adults. In a double-blind, randomized, crossover study, 12 healthy, older (60-70 yr) adults supplemented their diet for 3 days with either nitrate-rich concentrated beetroot juice (BR; 2 × 70 ml/day, ∼9.6 mmol/day NO(3)(-)) or a nitrate-depleted beetroot juice placebo (PL; 2 × 70 ml/day, ∼0.01 mmol/day NO(3)(-)). Before and after the intervention periods, resting blood pressure and plasma [nitrite] were measured, and subjects completed a battery of physiological and cognitive tests. Nitrate supplementation significantly increased plasma [nitrite] and reduced resting systolic (BR: 115 ± 9 vs. PL: 120 ± 6 mmHg; P < 0.05) and diastolic (BR: 70 ± 5 vs. PL: 73 ± 5 mmHg; P < 0.05) blood pressure. Nitrate supplementation resulted in a speeding of the Vo(2) mean response time (BR: 25 ± 7 vs. PL: 28 ± 7 s; P < 0.05) in the transition from standing rest to treadmill walking, although in contrast to our hypothesis, the O(2) cost of exercise remained unchanged. Functional capacity (6-min walk test), the muscle metabolic response to low-intensity exercise, brain metabolite concentrations, and cognitive function were also not altered. Dietary nitrate supplementation reduced resting blood pressure and improved Vo(2) kinetics during treadmill walking in healthy older adults but did not improve walking or cognitive performance. These results may have implications for the enhancement of cardiovascular health in older age.
Abstract.
Author URL.
Jones AM, Vanhatalo A, Bailey SJ (2013). Influence of dietary nitrate supplementation on exercise tolerance and performance.
Nestle Nutr Inst Workshop Ser,
75, 27-40.
Abstract:
Influence of dietary nitrate supplementation on exercise tolerance and performance.
Several recent studies indicate that supplementation of the diet with inorganic nitrate results in a significant reduction in pulmonary O2 uptake during sub-maximal exercise, an effect that appears to be related to enhanced skeletal muscle efficiency. The physiological mechanisms responsible for this effect are not completely understood but are presumably linked to the bioconversion of ingested nitrate into nitrite and thence to nitric oxide. Nitrite and/or nitric oxide may influence muscle contractile efficiency perhaps via effects on sarcoplasmic reticulum calcium handling or actin-myosin interaction, and may also improve the efficiency of mitochondrial oxidative phosphorylation. A reduced O2 cost of exercise can be observed within 3 h of the consumption of 5-6 mmol of nitrate, and this effect can be preserved for at least 15 days provided that the same 'dose' of nitrate is consumed daily. A reduced O2 cost of exercise following nitrate supplementation has now been reported for several types of exercise including cycling, walking, running, and knee extension exercise. Dietary nitrate supplementation has been reported to extend the time to exhaustion during high-intensity constant work rate exercise by 16-25% and to enhance cycling performance over 4, 10, and 16.1 km by 1-2% in recreationally active and moderately trained subjects. Although nitrate appears to be a promising 'new' ergogenic aid, additional research is required to determine the scope of its effects in different populations and different types of exercise.
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Author URL.
Fulford J, Winyard PG, Vanhatalo A, Bailey SJ, Blackwell JR, Jones AM (2013). Influence of dietary nitrate supplementation on human skeletal muscle metabolism and force production during maximum voluntary contractions.
Pflugers Arch,
465(4), 517-528.
Abstract:
Influence of dietary nitrate supplementation on human skeletal muscle metabolism and force production during maximum voluntary contractions.
Dietary nitrate supplementation, which enhances nitric oxide (NO) bioavailability, has previously been shown to contribute to improved exercise performance by reducing both oxygen cost and energy expenditure. In contrast, previous studies have indicated that NO can lower force production in vitro. To examine the role of dietary nitrates in regulating force generation under normal physiological conditions, we undertook an extended nitrate supplementation regime and determined force output and energy cost with a repeated isometric maximum voluntary contraction (MVC) protocol. In a double-blind, randomized, crossover design, eight participants received 0.5 l/day of nitrate-rich (BR) or nitrate-depleted (PL) beetroot juice for 15 days and completed an exercise protocol consisting of 50 MVCs at 2.5 h, 5 days and 15 days after the beginning of the supplementation period. No significant reduction in force output was determined for BR relative to PL for the peak contraction, the mean or the end force, and no significant time effect was found over the course of the supplementation period. There was a reduction in the mean PCr cost of exercise averaged over the BR supplementation trials, but this did not reach statistical significance for end exercise (BR 15.10 ± 4.14 mM, PL 17.10 ± 5.34 mM, P = 0.06) or the mean throughout the protocol (BR 15.96 ± 4.14 mM, PL 17.79 ± 4.51 mM, P = 0.06). However, a significant reduction in PCr cost per unit force output was found for BR at end exercise (P = 0.04). These results indicate that, under normal physiological conditions, increased NO bioavailability is not associated with a reduction of force-generating capability in human skeletal muscle and confirm that nitrate supplementation reduces the PCr cost of force production.
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Author URL.
Holliss BA, Fulford J, Vanhatalo A, Pedlar CR, Jones AM (2013). Influence of intermittent hypoxic training on muscle energetics and exercise tolerance.
J Appl Physiol (1985),
114(5), 611-619.
Abstract:
Influence of intermittent hypoxic training on muscle energetics and exercise tolerance.
Intermittent hypoxic training (IHT) is sometimes used by athletes to enhance nonhematological physiological adaptations to simulated altitude. We investigated whether IHT would result in greater improvements in muscle energetics and exercise tolerance compared with work-matched intermittent normoxic training (INT). Nine physically active men completed 3 wk of intensive, single-leg knee-extensor exercise training. Each training session consisted of 25 min of IHT (FiO2 14.5 ± 0.1%) with the experimental leg and 25 min of INT with the alternate leg, which served as a control. Before and after the training intervention, subjects completed a test protocol consisting of a bout of submaximal constant-work-rate exercise, a 24-s high-intensity exercise bout to quantify the phosphocreatine recovery time constant ([PCr]-τ), and an incremental test to the limit of tolerance. The tests were completed in normoxia and hypoxia in both INT and IHT legs. Muscle metabolism was assessed noninvasively using (31)P-magnetic resonance spectroscopy. Improvements in the time-to-exhaustion during incremental exercise were not significantly different between training conditions either in normoxia (INT, 28 ± 20% vs. IHT, 25 ± 9%; P = 0.86) or hypoxia (INT, 21 ± 10% vs. IHT, 15 ± 11%; P = 0.29). In hypoxia, [PCr]-τ was speeded slightly but significantly more post-IHT compared with post-INT (-7.3 ± 2.9 s vs. -3.7 ± 1.7 s; P < 0.01), but changes in muscle metabolite concentrations during exercise were essentially not different between IHT and INT. Under the conditions of this investigation, IHT does not appreciably alter muscle metabolic responses or incremental exercise performance compared with INT.
Abstract.
Author URL.
Chidnok W, Fulford J, Bailey SJ, Dimenna FJ, Skiba PF, Vanhatalo A, Jones AM (2013). Muscle metabolic determinants of exercise tolerance following exhaustion: relationship to the "critical power".
J Appl Physiol (1985),
115(2), 243-250.
Abstract:
Muscle metabolic determinants of exercise tolerance following exhaustion: relationship to the "critical power".
We tested the hypothesis that muscle high-energy phosphate compounds and metabolites related to the fatigue process would be recovered after exhaustion during recovery exercise performed below but not above critical power (CP) and that these changes would influence the capacity to continue exercise. Eight male subjects completed single-leg, knee-extension exercise to exhaustion (for ∼180 s) on three occasions, followed by a work-rate reduction to severe-intensity exercise, heavy-intensity exercise (CP differ according to whether the recovery exercise is performed below or above the CP. These findings confirm the importance of the CP as an intramuscular metabolic threshold that dictates the accumulation of fatigue-related metabolites and the capacity to tolerate high-intensity exercise.
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Author URL.
Chidnok W, DiMenna FJ, Fulford J, Bailey SJ, Skiba PF, Vanhatalo A, Jones AM (2013). Muscle metabolic responses during high-intensity intermittent exercise measured by (31)P-MRS: relationship to the critical power concept.
Am J Physiol Regul Integr Comp Physiol,
305(9), R1085-R1092.
Abstract:
Muscle metabolic responses during high-intensity intermittent exercise measured by (31)P-MRS: relationship to the critical power concept.
We investigated the responses of intramuscular phosphate-linked metabolites and pH (as assessed by (31)P-MRS) during intermittent high-intensity exercise protocols performed with different recovery-interval durations. Following estimation of the parameters of the power-duration relationship, i.e. the critical power (CP) and curvature constant (W'), for severe-intensity constant-power exercise, nine male subjects completed three intermittent exercise protocols to exhaustion where periods of high-intensity constant-power exercise (60 s) were separated by different durations of passive recovery (18 s, 30 s and 48 s). The tolerable duration of exercise was 304 ± 68 s, 516 ± 142 s, and 847 ± 240 s for the 18-s, 30-s, and 48-s recovery protocols, respectively (P < 0.05). The work done >CP (W>CP) was significantly greater for all intermittent protocols compared with the subjects' W', and this difference became progressively greater as recovery-interval duration was increased. The restoration of intramuscular phosphocreatine concentration during recovery was greatest, intermediate, and least for 48 s, 30 s, and 18 s of recovery, respectively (P < 0.05). The W>CP in excess of W' increased with greater durations of recovery, and this was correlated with the mean magnitude of muscle phosphocreatine reconstitution between work intervals (r = 0.61; P < 0.01). The results of this study show that during intermittent high-intensity exercise, recovery intervals allow intramuscular homeostasis to be restored, with the degree of restoration being related to the duration of the recovery interval. Consequently, and consistent with the intermittent CP model, the ability to perform W>CP during intermittent high-intensity exercise and, therefore, exercise tolerance, increases when recovery-interval duration is extended.
Abstract.
Author URL.
Vanhatalo A, Bailey SJ, DiMenna FJ, Blackwell JR, Wallis GA, Jones AM (2013). No effect of acute L-arginine supplementation on O₂ cost or exercise tolerance.
Eur J Appl Physiol,
113(7), 1805-1819.
Abstract:
No effect of acute L-arginine supplementation on O₂ cost or exercise tolerance.
The extent to which dietary supplementation with the nitric oxide synthase (NOS) substrate, L-arginine (ARG), impacts on NO production and NO-mediated physiological responses is controversial. This randomised, double blinded, cross-over study investigated the effects of acute ARG supplementation on NO biomarkers, O₂ cost of exercise and exercise tolerance in humans. In one experiment, 15 subjects completed moderate- and severe-intensity running bouts after acute supplementation with 6 g ARG or placebo (PLA). In another experiment, eight subjects completed moderate- and severe-intensity cycling bouts after acute supplementation with 6 g ARG plus 25 g of carbohydrate (ARG + CHO) or an energy-matched dose of carbohydrate alone (CHO). The plasma nitrite concentration was not different after ARG (Pre: 204 ± 79; Post: 241 ± 114 nM; P > 0.05) or ARG + CHO consumption (Pre: 304 ± 57; Post: 335 ± 116 nM; P > 0.05). During moderate-intensity exercise, the steady-state pulmonary VO₂ was not different, relative to the respective placebo conditions, after ARG (PLA: 2,407 ± 318, ARG: 2,422 ± 333 mL min(-1)) or ARG + CHO (CHO: 1,695 ± 304, ARG + CHO: 1,712 ± 312 mL min(-1)) ingestion (P > 0.05). The tolerable duration of severe exercise was also not significantly different (P > 0.05) after ingesting ARG (PLA: 551 ± 140, ARG: 552 ± 150 s) or ARG + CHO (CHO: 457 ± 182, ARG + CHO: 441 ± 221 s). In conclusion, acute dietary supplementation with ARG or ARG + CHO did not alter biomarkers of NO synthesis, O₂ cost of exercise or exercise tolerance in healthy subjects.
Abstract.
Author URL.
Chidnok W, Dimenna FJ, Bailey SJ, Burnley M, Wilkerson DP, Vanhatalo A, Jones AM (2013). V̇O<inf>2max</inf> is not altered by self-pacing during incremental exercise.
European Journal of Applied Physiology,
113(2), 529-539.
Abstract:
V̇O2max is not altered by self-pacing during incremental exercise
We tested the hypothesis that incremental cycling to exhaustion that is paced using clamps of the rating of perceived exertion (RPE) elicits higher V̇O2max values compared to a conventional ramp incremental protocol when test duration is matched. Seven males completed three incremental tests to exhaustion to measure V̇O2max. The incremental protocols were of similar duration and included: a ramp test at 30 W min-1 with constant cadence (RAMP1); a ramp test at 30 W min-1 with cadence free to fluctuate according to subject preference (RAMP2); and a self-paced incremental test in which the power output was selected by the subject according to prescribed increments in RPE (SPT). The subjects also completed a V̇O2max 'verification' test at a fixed high-intensity power output and a 3-min all-out test. No difference was found for V̇O 2max between the incremental protocols (RAMP1 = 4.33 ± 0.60 L min-1; RAMP2 = 4.31 ± 0.62 L min-1; SPT = 4.36 ± 0.59 L min-1; P > 0.05) nor between the incremental protocols and the peak V̇O2max measured during the 3-min all-out test (4.33 ± 0.68 L min-1) or the V̇O2max measured in the verification test (4.32 ± 0.69 L min-1). The integrated electromyogram, blood lactate concentration, heart rate and minute ventilation at exhaustion were not different (P > 0.05) between the incremental protocols. In conclusion, when test duration is matched, SPT does not elicit a higher V̇O2max compared to conventional incremental protocols. The striking similarity of V̇O2max measured across an array of exercise protocols indicates that there are physiological limits to the attainment of V̇O2max that cannot be exceeded by self-pacing. © 2012 Springer-Verlag.
Abstract.
Chidnok W, Dimenna FJ, Bailey SJ, Burnley M, Wilkerson DP, Vanhatalo A, Jones AM (2013). V̇O<inf>2max</inf> is not altered by self-pacing during incremental exercise: Reply to the letter of Alexis R. Mauger. European Journal of Applied Physiology, 113(2), 543-544.
2012
Jones AM, Bailey SJ, Vanhatalo A (2012). DIetary Nitrate and O2 consumption during exercise. In (Ed)
Acute Topics in Sport Nutrition, 29-35.
Abstract:
DIetary Nitrate and O2 consumption during exercise
Abstract.
Jones AM, Bailey SJ, Vanhatalo A (2012). Dietary nitrate and O₂ consumption during exercise.
Med Sport Sci,
59, 29-35.
Abstract:
Dietary nitrate and O₂ consumption during exercise.
Recent studies have investigated the influence of dietary nitrate supplementation on the physiological responses to exercise. Specifically, it has been reported that enhancing nitric oxide (NO) bioavailability through supplementation of the diet with nitrate salts or nitrate-rich beetroot juice reduces the O(2) cost of exercise and improves exercise performance. The lower O(2) cost for a given sub-maximal work rate following nitrate ingestion indicates that muscle efficiency is enhanced either as a consequence of a reduced energy cost of contraction or enhanced mitochondrial efficiency. The positive effects of nitrate supplementation on the O(2) cost of sub-maximal exercise can be manifested acutely (i.e. 2.5 h following ingestion) and maintained for at least 15 days if supplementation is continued. Most recently, the influence of dietary nitrate supplementation on time trial performance in competitive cyclists has been investigated. Studies have shown a 1-2% reduction in the time to complete time trial distances between 4 and 16 km. The dose of nitrate that has been shown to improve exercise efficiency can readily be achieved through the consumption of 0.5 litre of beetroot juice or an equivalent high-nitrate foodstuff. Following a 5- to 6-mmol bolus of nitrate, plasma [nitrite] typically peaks within 2-3 h and remains elevated for a further 6-9 h before declining towards baseline. Therefore, consuming nitrate approximately 3 h prior to competition or training is recommended if athletes wish to explore the ergogenic potential of nitrate supplementation.
Abstract.
Author URL.
Burnley M, Vanhatalo A, Jones AM (2012). Distinct profiles of neuromuscular fatigue during muscle contractions below and above the critical torque in humans.
J Appl Physiol (1985),
113(2), 215-223.
Abstract:
Distinct profiles of neuromuscular fatigue during muscle contractions below and above the critical torque in humans.
Whether the transition in fatigue processes between "low-intensity" and "high-intensity" contractions occurs gradually, as the torque requirements are increased, or whether this transition occurs more suddenly at some identifiable "threshold", is not known. We hypothesized that the critical torque (CT; the asymptote of the torque-duration relationship) would demarcate distinct profiles of central and peripheral fatigue during intermittent isometric quadriceps contractions (3-s contraction, 2-s rest). Nine healthy men performed seven experimental trials to task failure or for up to 60 min, with maximal voluntary contractions (MVCs) performed at the end of each minute. The first five trials were performed to determine CT [~35-55% MVC, denoted severe 1 (S1) to severe 5 (S5) in ascending order], while the remaining two trials were performed 10 and 20% below the CT (denoted CT-10% and CT-20%). Dynamometer torque and the electromyogram of the right vastus lateralis were sampled continuously. Peripheral and central fatigue was determined from the fall in potentiated doublet torque and voluntary activation, respectively. Above CT, contractions progressed to task failure in ~3-18 min, at which point the MVC did not differ from the target torque (S1 target, 88.7 ± 4.3 N·m vs. MVC, 89.3 ± 8.8 N·m, P = 0.94). The potentiated doublet fell significantly in all trials, and voluntary activation was reduced in trials S1-S3, but not trials S4 and S5. Below CT, contractions could be sustained for 60 min on 17 of 18 occasions. Both central and peripheral fatigue developed, but there was a substantial reserve in MVC torque at the end of the task. The rate of global and peripheral fatigue development was four to five times greater during S1 than during CT-10% (change in MVC/change in time S1 vs. CT-10%: -7.2 ± 1.4 vs. -1.5 ± 0.4 N·m·min(-1)). These results demonstrate that CT represents a critical threshold for neuromuscular fatigue development.
Abstract.
Author URL.
Chidnok W, Dimenna FJ, Bailey SJ, Vanhatalo A, Morton RH, Wilkerson DP, Jones AM (2012). Exercise tolerance in intermittent cycling: application of the critical power concept.
Med Sci Sports Exerc,
44(5), 966-976.
Abstract:
Exercise tolerance in intermittent cycling: application of the critical power concept.
PURPOSE: This study tested the relevance of the critical power (CP) model for explaining exercise tolerance during intermittent high-intensity exercise with different recovery intensities. METHODS: After estimation of CP and W' from a 3-min all-out test, seven male subjects completed, in randomized order, a cycle test to exhaustion at a severe-intensity constant-work-rate (S-CWR) and four cycle tests to exhaustion using different intermittent ("work-recovery") protocols (i.e. severe-severe (S-S), severe-heavy (S-H), severe-moderate (S-M), and severe-light (S-L)). RESULTS: the tolerable duration of exercise in S-CWR was 384 ± 48 s, and this was increased by 47%, 100%, and 219% for S-H, S-M, and S-L, respectively (all P < 0.05). Consistent with this, compared with S-CWR (22.9 ± 7.4 kJ), the work done above the CP was significantly greater by 46%, 98%, and 220% for S-H, S-M, and S-L, respectively (all P < 0.05). The slope of the relationship between V˙O₂ and time was significantly reduced for S-H, S-M, and S-L (0.09 ± 0.02, 0.09 ± 0.01, and 0.07 ± 0.02 L·min⁻², respectively) compared with S-CWR (0.16 ± 0.03 L·min⁻², P < 0.05). In addition, the slope of the relationship between integrated EMG and time showed a systematic decline for S-H, S-M, and S-L compared with S-CWR (P < 0.05). CONCLUSIONS: These results indicate that, when recovery intervals during intermittent exercise are performed below the CP, exercise tolerance is improved in proportion to the reconstitution of the finite W'. The enhanced exercise tolerance with the lower-intensity recovery intervals was associated with a blunted increase in both V˙O₂ and integrated EMG with time.
Abstract.
Author URL.
Wilkerson DP, Hayward GM, Bailey SJ, Vanhatalo A, Blackwell JR, Jones AM (2012). Influence of acute dietary nitrate supplementation on 50 mile time trial performance in well-trained cyclists.
European Journal of Applied Physiology,
112(12), 4127-4134.
Abstract:
Influence of acute dietary nitrate supplementation on 50 mile time trial performance in well-trained cyclists
Dietary nitrate supplementation has been reported to improve short distance time trial (TT) performance by 1-3 % in club-level cyclists. It is not known if these ergogenic effects persist in longer endurance events or if dietary nitrate supplementation can enhance performance to the same extent in better trained individuals. Eight well-trained male cyclists performed two laboratorybased 50 mile TTs: (1) 2.5 h after consuming 0.5 L of nitrate-rich beetroot juice (BR) and (2) 2.5 h after consuming 0.5 L of nitrate-depleted BR as a placebo (PL). BR significantly elevated plasma [NO2 -] (BR: 472 ± 96 vs. PL: 379 ± 94 nM; P0.05) but oxygen uptake ( VO2) tended to be lower in BR (P = 0.06), resulting in a significantly greater PO/ VO2 ratio (BR: 67.4 ± 5.5 vs. PL: 65.3 ± 4.8 W L min-1; P
Abstract.
Parker Simpson L, Jones AM, Vanhatalo A, Wilkerson DP (2012). Influence of initial metabolic rate on the power-duration relationship for all-out exercise.
Eur J Appl Physiol,
112(7), 2467-2473.
Abstract:
Influence of initial metabolic rate on the power-duration relationship for all-out exercise.
A single 3-min all-out cycling test can be used to estimate the power asymptote (critical power, CP) and the curvature constant (W') of the power-duration relationship for severe-intensity exercise. It was hypothesized that when exercise immediately preceding the 3-min all-out test was performed
Abstract.
Author URL.
Skiba PF, Chidnok W, Vanhatalo A, Jones AM (2012). Modeling the expenditure and reconstitution of work capacity above critical power.
Medicine and Science in Sports and Exercise,
44(8), 1526-1532.
Abstract:
Modeling the expenditure and reconstitution of work capacity above critical power
Purpose: the critical power (CP) model includes two constants: the CP and the W′ [P = (W′/t) + CP]. The W′ is the finite work capacity available above CP. Power output above CP results in depletion of the W′ complete depletion of the W′ results in exhaustion. Monitoring the W′ may be valuable to athletes during training and competition. Our purpose was to develop a function describing the dynamic state of the W′ during intermittent exercise. Methods: After determination of V̇O2max, CP, and W′, seven subjects completed four separate exercise tests on a cycle ergometer on different days. Each protocol comprised a set of intervals: 60 s at a severe power output, followed by 30-s recovery at a lower prescribed power output. The intervals were repeated until exhaustion. These data were entered into a continuous equation predicting balance of W′ remaining, assuming exponential reconstitution of the W′. The time constant was varied by an iterative process until the remaining modeled W′ = 0 at the point of exhaustion. Results: the time constants of W′ recharge were negatively correlated with the difference between sub-CP recovery power and CP. The relationship was best fit by an exponential (r = 0.77). The model-predicted W′ balance correlated with the temporal course of the rise in V̇O2 (r = 0.82-0.96). The model accurately predicted exhaustion of the W′ in a competitive cyclist during a road race. Conclusions: We have developed a function to track the dynamic state of the W′ during intermittent exercise. This may have important implications for the planning and real-time monitoring of athletic performance. © 2012 by the American College of Sports Medicine.
Abstract.
Bailey SJ, Vanhatalo A, Winyard PG, Jones AM (2012). The nitrate-nitrite-nitric oxide pathway: its role in human exercise physiology.
European Journal of Sport Science,
12(4), 309-320.
Abstract:
The nitrate-nitrite-nitric oxide pathway: its role in human exercise physiology
Nitric oxide (NO) is a potent signalling molecule that influences an array of physiological responses. It was traditionally assumed that NO was derived exclusively via the nitric oxide synthase (NOS) family of enzymes. This complex reaction requires a five electron oxidation of L-arginine and is contingent on the presence of numerous essential substrates (including O 2) and co-factors. Recently an additional, O 2-independent, NO generating pathway has been identified, where nitrite (NO 2-) can undergo a simple one electron reduction to yield NO. NO 2- is produced endogenously from the oxidation of NO and also from the reduction of dietary nitrate (NO 3-) by facultative bacteria residing on the tongue. Recent data show that dietary NO 3- supplementation, which increases the circulating plasma [NO 2-], reduces the O 2 cost of submaximal exercise in healthy humans. This finding is striking given that efficiency during moderate-intensity exercise has been considered to be immutable. There is evidence that the muscle ATP turnover at a fixed work rate is reduced and the mitochondrial P/O ratio is increased following NO 3- supplementation, which offers important insights into the physiological bases for the reduced V̇O 2 during exercise. NO 3- supplementation has also been shown to improve exercise performance in both healthy and patient populations. Therefore, dietary NO 3- supplementation may represent a practical and cost-effective method to improve exercise efficiency and exercise tolerance in humans. Given that a NO 3--rich diet may have numerous cardiovascular and other health benefits, dietary NO 3- intake may have important implications for human lifelong health and performance. © 2012 Copyright European College of Sport Science.
Abstract.
2011
Vanhatalo A, Jones AM, Burnley M (2011). Application of critical power in sport.
Int J Sports Physiol Perform,
6(1), 128-136.
Abstract:
Application of critical power in sport.
The critical power (CP) is mathematically defined as the power-asymptote of the hyperbolic relationship between power output and time-to-exhaustion. Physiologically, the CP represents the boundary between the steady-state and nonsteady state exercise intensity domains and therefore may provide a more meaningful index of performance than other well-known landmarks of aerobic fitness such as the lactate threshold and the maximal O2 uptake. Despite the potential importance to sports performance, the CP is often misinterpreted as a purely mathematical construct which lacks physiological meaning and only in recent years has this concept begun to emerge as valid and useful technique for monitoring endurance fitness. This commentary defines the basic principles of the CP concept, outlines its importance to high-intensity exercise performance, and provides an overview of the current methods available for its assessment. Interventions including training, pacing and prior exercise can be used to alter the parameters of the power-time relationship. A future challenge lies in optimizing such interventions in order to positively affect the parameters of the power-time relationship and thereby enhance sports performance in specific events.
Abstract.
Author URL.
Vanhatalo A, Fulford J, Bailey SJ, Blackwell JR, Winyard PG, Jones AM (2011). Dietary nitrate reduces muscle metabolic
perturbation and improves exercise tolerance in
hypoxia.
Journal of PhysiologyAbstract:
Dietary nitrate reduces muscle metabolic
perturbation and improves exercise tolerance in
hypoxia
Exercise in hypoxia is associated with reduced muscle oxidative function and impaired
exercise tolerance. We hypothesised that dietary nitrate supplementation (which increases
plasma [nitrite] and thus NO bioavailability) would ameliorate the adverse effects of hypoxia
on muscle metabolism and oxidative function. In a double-blind, randomised crossover study,
nine healthy subjects completed knee-extension exercise to the limit of tolerance (Tlim), once
in normoxia (20.9% O2; CON) and twice in hypoxia (14.5% O2). During 24 h prior to the
hypoxia trials, subjects consumed 0.75 L of nitrate-rich beetroot juice (9.3 mmol nitrate; HBR)
or 0.75 L of nitrate-depleted beetroot juice as a placebo (0.006 mmol nitrate; H-PL).
Muscle metabolism was assessed using calibrated 31P-MRS. Plasma [nitrite] was elevated
(P
Abstract.
Bailey SJ, Fulford J, Vanhatalo A, Winyard P, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM (2011). Dietary nitrate supplementation enhances muscle efficiency during knee-extensor exercise in humans.
Bailey SJ, Vanhatalo A, DiMenna FJ, Wilkerson DP, Jones AM (2011). Fast-start strategy improves VO2 kinetics and high-intensity exercise performance.
Med Sci Sports Exerc,
43(3), 457-467.
Abstract:
Fast-start strategy improves VO2 kinetics and high-intensity exercise performance.
PURPOSE: the purpose of this study was to investigate the influence of pacing strategy on pulmonary VO2 kinetics and performance during high-intensity exercise. METHODS: Seven males completed 3- and 6-min bouts of cycle exercise on three occasions with the bouts initiated using an even-start (ES; constant work rate), fast-start (FS), or slow-start (SS) pacing strategy. In all conditions, subjects completed an all-out sprint over the final 60 s of the test as a measure of performance. RESULTS: for the 3-min exercise bouts, the mean response time (MRT) for the VO2 kinetics over the pacing phase was shortest in FS (35 ± 6 s), longest in SS (55 ± 14 s), and intermediate in ES (41 ± 10 s) (P < 0.05 for all comparisons). For the 6-min bouts, the VO2 MRT was longer in SS (56 ± 15 s) than that in FS and ES (38 ± 7 and 42 ± 6 s, respectively, P < 0.05). The VO2 at the end of exercise was not different from the VO2max during the 6-min exercise bouts or 3-FS but was lower than VO2max for 3-ES and 3-SS (P < 0.05). The end-sprint performance was significantly enhanced in 3-FS compared with 3-ES and 3-SS (mean power = 374 ± 68 vs 348 ± 61 and 345 ± 71 W, respectively; P < 0.05). However, end-sprint performance was unaffected by pacing strategy in the 6-min bouts. CONCLUSIONS: These data indicate that an FS pacing strategy significantly improves performance during 3-min bouts of high-intensity exercise by speeding VO2 kinetics and enabling the attainment of VO2max.
Abstract.
Author URL.
Bailey SJ, Winyard PG, Blackwell JR, Vanhatalo A, Lansley KE, Dimenna FJ, Wilkerson DP, Campbell IT, Jones AM (2011). Influence of N-acetylcysteine administration on pulmonary O₂ uptake kinetics and exercise tolerance in humans.
Respir Physiol Neurobiol,
175(1), 121-129.
Abstract:
Influence of N-acetylcysteine administration on pulmonary O₂ uptake kinetics and exercise tolerance in humans.
We investigated the influence of the antioxidant N-acetylcysteine (NAC) on plasma nitrite concentration ([NO₂⁻]), pulmonary oxygen uptake (V(O₂)) kinetics and exercise tolerance. Eight males completed 'step' moderate- and severe-intensity cycle exercise tests following infusion of either NAC (125 mg kg⁻¹ h⁻¹ for 15 min followed by 25 mg kg⁻¹ h⁻¹ until the termination of exercise) or Placebo (PLA; saline). Following the initial loading phase, NAC infusion elevated plasma free sulfhydryl groups compared to placebo (PLA: 4 ± 2 vs. NAC: 13 ± 3 μ M g⁻¹; P < 0.05) and this elevation was preserved throughout the protocol. The administration of NAC did not significantly influence plasma [NO₂⁻] or V(O₂) kinetics during either moderate- or severe-intensity exercise. Although NAC did not significantly alter severe-intensity exercise tolerance at the group mean level (PLA: 776 ± 181 vs. NAC: 878 ± 284 s; P > 0.05), there was appreciable inter-subject variability in the response: four subjects had small reductions in exercise tolerance with NAC compared to PLA (-4%, -8%, -11%, and -14%) while the other four showed substantial improvements (+24%, +24%, +40%, and +69%). The results suggest that exercise-induced redox perturbations may contribute to fatigue development in recreationally-active adults.
Abstract.
Author URL.
Skiba PF, Chidnok W, Vanhatalo A, Jones AM (2011). Modeling Charge / Discharge Kinetics of the W' During Intermittent Exercise.
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE,
43(5), 141-141.
Author URL.
Vanhatalo A, Poole DC, DiMenna FJ, Bailey SJ, Jones AM (2011). Muscle fiber recruitment and the slow component of O2 uptake: constant work rate vs. all-out sprint exercise.
Am J Physiol Regul Integr Comp Physiol,
300(3), R700-R707.
Abstract:
Muscle fiber recruitment and the slow component of O2 uptake: constant work rate vs. all-out sprint exercise.
The slow component of pulmonary O(2) uptake (Vo(2)) during constant work rate (CWR) high-intensity exercise has been attributed to the progressive recruitment of (type II) muscle fibers. We tested the following hypotheses: 1) the Vo(2) slow component gain would be greater in a 3-min all-out cycle test than in a work-matched CWR test, and 2) the all-out test would be associated with a progressive decline, and the CWR test with a progressive increase, in muscle activation, as estimated from the electromyogram (EMG) of the vastus lateralis muscle. Eight men (aged 21-39 yr) completed a ramp incremental test, a 3-min all-out test, and a work- and time-matched CWR test to exhaustion. The maximum Vo(2) attained in an initial ramp incremental test (3.97 ± 0.83 l/min) was reached in both experimental tests (3.99 ± 0.84 and 4.03 ± 0.76 l/min for all-out and CWR, respectively). The Vo(2) slow component was greater (P < 0.05) in the all-out test (1.21 ± 0.31 l/min, 4.2 ± 2.2 ml·min(-1)·W(-1)) than in the CWR test (0.59 ± 0.22 l/min, 1.70 ± 0.5 ml·min(-1)·W(-1)). The integrated EMG declined by 26% (P < 0.001) during the all-out test and increased by 60% (P < 0.05) during the CWR test from the first 30 s to the last 30 s of exercise. The considerable reduction in muscle efficiency in the all-out test in the face of a progressively falling integrated EMG indicates that progressive fiber recruitment is not requisite for development of the Vo(2) slow component during voluntary exercise in humans.
Abstract.
Author URL.
Jones AM, Bailey SJ, Vanhatalo A, Fulford J, Gilchrist M, Benjamin N, Winyard PG (2011). Reply to Lundberg, Larsen, and Weitzberg.
J Appl Physiol (1985),
111(2).
Author URL.
Jones AM, Vanhatalo A, Burnley M, Morton RH, Poole DC (2011). Response. Med Sci Sports Exerc, 43(3).
2010
Bailey SJ, Winyard PG, Vanhatalo A, Blackwell JR, DiMenna FJ, Wilkerson DP, Jones AM (2010). Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance.
J Appl Physiol (1985),
109(5), 1394-1403.
Abstract:
Acute L-arginine supplementation reduces the O2 cost of moderate-intensity exercise and enhances high-intensity exercise tolerance.
It has recently been reported that dietary nitrate (NO(3)(-)) supplementation, which increases plasma nitrite (NO(2)(-)) concentration, a biomarker of nitric oxide (NO) availability, improves exercise efficiency and exercise tolerance in healthy humans. We hypothesized that dietary supplementation with L-arginine, the substrate for NO synthase (NOS), would elicit similar responses. In a double-blind, crossover study, nine healthy men (aged 19-38 yr) consumed 500 ml of a beverage containing 6 g of l-arginine (Arg) or a placebo beverage (PL) and completed a series of "step" moderate- and severe-intensity exercise bouts 1 h after ingestion of the beverage. Plasma NO(2)(-) concentration was significantly greater in the Arg than the PL group (331 ± 198 vs. 159 ± 102 nM, P < 0.05) and systolic blood pressure was significantly reduced (123 ± 3 vs. 131 ± 5 mmHg, P < 0.01). The steady-state O(2) uptake (VO(2)) during moderate-intensity exercise was reduced by 7% in the Arg group (1.48 ± 0.12 vs. 1.59 ± 0.14 l/min, P < 0.05). During severe-intensity exercise, the Vo(2) slow component amplitude was reduced (0.58 ± 0.23 and 0.76 ± 0.29 l/min in Arg and PL, respectively, P < 0.05) and the time to exhaustion was extended (707 ± 232 and 562 ± 145 s in Arg and PL, respectively, P < 0.05) following consumption of Arg. In conclusion, similar to the effects of increased dietary NO(3)(-) intake, elevating NO bioavailability through dietary L-Arg supplementation reduced the O(2) cost of moderate-intensity exercise and blunted the VO(2) slow component and extended the time to exhaustion during severe-intensity exercise.
Abstract.
Author URL.
Vanhatalo A, Bailey SJ, Blackwell JR, DiMenna FJ, Pavey TG, Wilkerson DP, Benjamin N, Winyard PG, Jones AM (2010). Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise.
Am J Physiol Regul Integr Comp Physiol,
299(4), R1121-R1131.
Abstract:
Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise.
Dietary nitrate (NO(3)(-)) supplementation with beetroot juice (BR) over 4-6 days has been shown to reduce the O(2) cost of submaximal exercise and to improve exercise tolerance. However, it is not known whether shorter (or longer) periods of supplementation have similar (or greater) effects. We therefore investigated the effects of acute and chronic NO(3)(-) supplementation on resting blood pressure (BP) and the physiological responses to moderate-intensity exercise and ramp incremental cycle exercise in eight healthy subjects. Following baseline tests, the subjects were assigned in a balanced crossover design to receive BR (0.5 l/day; 5.2 mmol of NO(3)(-)/day) and placebo (PL; 0.5 l/day low-calorie juice cordial) treatments. The exercise protocol (two moderate-intensity step tests followed by a ramp test) was repeated 2.5 h following first ingestion (0.5 liter) and after 5 and 15 days of BR and PL. Plasma nitrite concentration (baseline: 454 ± 81 nM) was significantly elevated (+39% at 2.5 h postingestion; +25% at 5 days; +46% at 15 days; P < 0.05) and systolic and diastolic BP (baseline: 127 ± 6 and 72 ± 5 mmHg, respectively) were reduced by ∼4% throughout the BR supplementation period (P < 0.05). Compared with PL, the steady-state Vo(2) during moderate exercise was reduced by ∼4% after 2.5 h and remained similarly reduced after 5 and 15 days of BR (P < 0.05). The ramp test peak power and the work rate at the gas exchange threshold (baseline: 322 ± 67 W and 89 ± 15 W, respectively) were elevated after 15 days of BR (331 ± 68 W and 105 ± 28 W; P < 0.05) but not PL (323 ± 68 W and 84 ± 18 W). These results indicate that dietary NO(3)(-) supplementation acutely reduces BP and the O(2) cost of submaximal exercise and that these effects are maintained for at least 15 days if supplementation is continued.
Abstract.
Author URL.
Jones AM, Vanhatalo A, Burnley M, Morton RH, Poole DC (2010). Critical power: implications for determination of V˙O2max and exercise tolerance.
Med Sci Sports Exerc,
42(10), 1876-1890.
Abstract:
Critical power: implications for determination of V˙O2max and exercise tolerance.
For high-intensity muscular exercise, the time-to-exhaustion (t) increases as a predictable and hyperbolic function of decreasing power (P) or velocity (V ). This relationship is highly conserved across diverse species and different modes of exercise and is well described by two parameters: the "critical power" (CP or CV), which is the asymptote for power or velocity, and the curvature constant (W') of the relationship such that t = W'/(P - CP). CP represents the highest rate of energy transduction (oxidative ATP production, V˙O2) that can be sustained without continuously drawing on the energy store W' (composed in part of anaerobic energy sources and expressed in kilojoules). The limit of tolerance (time t) occurs when W' is depleted. The CP concept constitutes a practical framework in which to explore mechanisms of fatigue and help resolve crucial questions regarding the plasticity of exercise performance and muscular systems physiology. This brief review presents the practical and theoretical foundations for the CP concept, explores rigorous alternative mathematical approaches, and highlights exciting new evidence regarding its mechanistic bases and its broad applicability to human athletic performance.
Abstract.
Author URL.
Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM (2010). Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans.
J Appl Physiol (1985),
109(1), 135-148.
Abstract:
Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans.
The purpose of this study was to elucidate the mechanistic bases for the reported reduction in the O(2) cost of exercise following short-term dietary nitrate (NO(3)(-)) supplementation. In a randomized, double-blind, crossover study, seven men (aged 19-38 yr) consumed 500 ml/day of either nitrate-rich beet root juice (BR, 5.1 mmol of NO(3)(-)/day) or placebo (PL, with negligible nitrate content) for 6 consecutive days, and completed a series of low-intensity and high-intensity "step" exercise tests on the last 3 days for the determination of the muscle metabolic (using (31)P-MRS) and pulmonary oxygen uptake (Vo(2)) responses to exercise. On days 4-6, BR resulted in a significant increase in plasma [nitrite] (mean +/- SE, PL 231 +/- 76 vs. BR 547 +/- 55 nM; P < 0.05). During low-intensity exercise, BR attenuated the reduction in muscle phosphocreatine concentration ([PCr]; PL 8.1 +/- 1.2 vs. BR 5.2 +/- 0.8 mM; P < 0.05) and the increase in Vo(2) (PL 484 +/- 41 vs. BR 362 +/- 30 ml/min; P < 0.05). During high-intensity exercise, BR reduced the amplitudes of the [PCr] (PL 3.9 +/- 1.1 vs. BR 1.6 +/- 0.7 mM; P < 0.05) and Vo(2) (PL 209 +/- 30 vs. BR 100 +/- 26 ml/min; P < 0.05) slow components and improved time to exhaustion (PL 586 +/- 80 vs. BR 734 +/- 109 s; P < 0.01). The total ATP turnover rate was estimated to be less for both low-intensity (PL 296 +/- 58 vs. BR 192 +/- 38 microM/s; P < 0.05) and high-intensity (PL 607 +/- 65 vs. BR 436 +/- 43 microM/s; P < 0.05) exercise. Thus the reduced O(2) cost of exercise following dietary NO(3)(-) supplementation appears to be due to a reduced ATP cost of muscle force production. The reduced muscle metabolic perturbation with NO(3)(-) supplementation allowed high-intensity exercise to be tolerated for a greater period of time.
Abstract.
Author URL.
Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM (2010). Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. (vol 109, pg 135, 2010).
JOURNAL OF APPLIED PHYSIOLOGY,
109(3), 943-943.
Author URL.
Vanhatalo A, McNaughton LR, Siegler J, Jones AM (2010). Effect of induced alkalosis on the power-duration relationship of ‘all-out’ exercise.
Medicine & Science in Sports & ExerciseAbstract:
Effect of induced alkalosis on the power-duration relationship of ‘all-out’ exercise
Purpose:. Pre-exercise alkalosis may improve sprint performance by facilitating H+ efflux from the active muscle. We tested the hypotheses that sodium bicarbonate ingestion would result in no alteration in critical power (CP) but would improve performance in a 3-min all-out cycling test by increasing the total amount of work done above CP (W′). Methods:. Eight habitually active subjects completed 3-min all-out sprints in a blind randomized design following a dose of 0.3 g•kg-1 of either sodium bicarbonate (BC) or 0.045 g•kg-1 of a sodium chloride placebo (PL). The CP was calculated as the mean power output over the final 30 s of the test and the W′ was estimated as the power-time integral >CP. Results:. The BC dose was effective in inducing pre-exercise alkalosis, as indicated by changes in blood pH (PL: 7.40 ± 0.02 vs. BC: 7.46 ± 0.01, P
Abstract.
DiMenna FJ, Bailey SJ, Vanhatalo A, Chidnok W, Jones AM (2010). Elevated baseline VO2 per se does not slow O2 uptake kinetics during work-to-work exercise transitions.
J Appl Physiol (1985),
109(4), 1148-1154.
Abstract:
Elevated baseline VO2 per se does not slow O2 uptake kinetics during work-to-work exercise transitions.
We investigated whether the characteristic slowing of pulmonary oxygen uptake (VO2) kinetics during "work-to-work" exercise is attributable to elevations in baseline metabolic rate (VO2) as opposed to the elevated baseline work rate, per se. We hypothesized that a step transition to a higher work rate from "unloaded" cycling, but with elevations in VO2 [and heart rate (HR)] reflective of a work-to-work transition, would result in a lengthened phase II time constant (τ(p)). Seven male subjects (mean ± SD age 27 ± 10 yr) completed 1) transitions to a high-intensity work rate from a moderate-intensity work rate (M→H) and 2) two consecutive bouts of high-intensity exercise (U→H and E→H, respectively) initiated from unloaded cycling, with the time separating the exercise bouts chosen such that the baseline VO2 for the second transition was similar to the baseline VO2 for the M→H transition. The τ(p) for M→H (48 ± 16 s) was significantly greater (P < 0.05) than the τ(p) for U→H (28 ± 8 s) and E→H (27 ± 6 s), which did not differ significantly. These findings suggest that the altered VO2 dynamics that are observed during work-to-work exercise are not related to the elevated baseline VO2 (or HR) per se; rather, these effects appear to be linked to the elevated baseline work rate, which would be expected to dictate the subsequent muscle fiber recruitment profile.
Abstract.
Author URL.
Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM (2010). Errtum: Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans (Journal of Applied Physiology (2010) 109 (135-148)). Journal of Applied Physiology, 109(3).
Vanhatalo A, Fulford J, DiMenna FJ, Jones AM (2010). Influence of hyperoxia on muscle metabolic responses and the power-duration relationship during severe-intensity exercise in humans: a 31P magnetic resonance spectroscopy study.
Exp Physiol,
95(4), 528-540.
Abstract:
Influence of hyperoxia on muscle metabolic responses and the power-duration relationship during severe-intensity exercise in humans: a 31P magnetic resonance spectroscopy study.
Severe-intensity constant-work-rate exercise results in the attainment of maximal oxygen uptake, but the muscle metabolic milieu at the limit of tolerance (T(lim)) for such exercise remains to be elucidated. We hypothesized that T(lim) during severe-intensity exercise would be associated with the attainment of consistently low values of intramuscular phosphocreatine ([PCr]) and pH, as determined using (31)P magnetic resonance spectroscopy, irrespective of the work rate and the inspired O(2) fraction. We also hypothesized that hyperoxia would increase the asymptote of the hyperbolic power-duration relationship (the critical power, CP) without altering the curvature constant (W). Seven subjects (mean +/- s.d. age 30 +/- 9 years) completed four constant-work-rate knee-extension exercise bouts to the limit of tolerance (range, 3-10 min) both in normoxia (N) and in hyperoxia (H; 70% O(2)) inside the bore of 1.5 T superconducting magnet. The [PCr] (approximately 5-10% of resting baseline) and pH (approximately 6.65) at the limit of tolerance during each of the four trials was not significantly different either in normoxia or in hyperoxia. At the same fixed work rate, the overall rate at which [PCr] fell with time was attenuated in hyperoxia (mean response time: N, 59 +/- 20 versus H, 116 +/- 46 s; P < 0.05). The CP was higher (N, 16.1 +/- 2.6 versus H, 18.0 +/- 2.3 W; P < 0.05) and the W was lower (N, 1.92 +/- 0.70 versus H, 1.48 +/- 0.31 kJ; P < 0.05) in hyperoxia compared with normoxia. These data indicate that T(lim) during severe-intensity exercise is associated with the attainment of consistently low values of muscle [PCr] and pH. The CP and W parameters of the power-duration relationship were both sensitive to the inspiration of hyperoxic gas.
Abstract.
Author URL.
Dimenna FJ, Fulford J, Bailey SJ, Vanhatalo A, Wilkerson DP, Jones AM (2010). Influence of priming exercise on muscle [PCr] and pulmonary O2 uptake dynamics during 'work-to-work' knee-extension exercise.
Respir Physiol Neurobiol,
172(1-2), 15-23.
Abstract:
Influence of priming exercise on muscle [PCr] and pulmonary O2 uptake dynamics during 'work-to-work' knee-extension exercise.
Metabolic transitions from rest to high-intensity exercise were divided into two discrete steps (i.e. rest-to-moderate-intensity (R-->M) and moderate-to-high-intensity (M-->H)) to explore the effect of prior high-intensity 'priming' exercise on intramuscular [PCr] and pulmonary VO₂ kinetics for different sections of the motor unit pool. It was hypothesized that [PCr] and VO₂ kinetics would be unaffected by priming during R-->M exercise, but that the time constants (tau) describing the fundamental [PCr] response and the phase II VO₂ response would be significantly reduced by priming for M-->H exercise. On three separate occasions, six male subjects completed two identical R-->M/M-->H 'work-to-work' prone knee-extension exercise bouts separated by 5min rest. Two trials were performed with measurement of pulmonary VO₂ and the integrated electromyogram (iEMG) of the right m. vastus lateralis. The third trial was performed within the bore of a 1.5-T superconducting magnet for (31)P-MRS assessment of muscle metabolic responses. Priming did not significantly affect the [PCr] or VO₂ tau during R-->M ([PCr] tau Unprimed: 24+/-16 vs. Primed: 22+/-14s; VO₂ tau Unprimed: 26+/-8 vs. Primed: 25+/-9s) or M-->H transitions ([PCr] tau Unprimed: 30+/-5 vs. Primed: 32+/-7s; VO₂ tau Unprimed: 37+/-5 vs. Primed: 38+/-9s). However, it did reduce the amplitudes of the [PCr] and VO₂ slow components by 50% and 46%, respectively, during M-->H (PH exercise after priming. It is concluded that the tau for the initial exponential change of muscle [PCr] and pulmonary VO₂ following the transition from moderate-to-high-intensity prone knee-extension exercise is not altered by priming exercise.
Abstract.
Author URL.
Burnley M, Vanhatalo A, Fulford J, Jones AM (2010). Similar metabolic perturbations during all-out and constant force exhaustive exercise in humans: a (31)P magnetic resonance spectroscopy study.
Exp Physiol,
95(7), 798-807.
Abstract:
Similar metabolic perturbations during all-out and constant force exhaustive exercise in humans: a (31)P magnetic resonance spectroscopy study.
It is not possible to attain a metabolic steady state during exercise above the so-called critical force or critical power. We tested the hypothesis that the muscle metabolic perturbations at the end of a bout of maximal isometric contractions, which yield a stable end-test force (equal to the critical force), would be similar to that at task failure following submaximal contractions performed above the critical force. Eight healthy subjects (four female) performed isometric single knee-extension exercise in the bore of a 1.5 T superconducting magnet on two occasions. Following familiarization, subjects performed the following exercises: (1) 60 maximal contractions (3 s contraction, 2 s rest); and (2) submaximal contractions (the same contraction regime performed at 54 +/- 8% maximal voluntary contraction) to task failure. Phosphocreatine (PCr), inorganic phosphate (P(i)) and diprotonated phosphate (H(2)PO(4)()) concentrations and pH were determined using (31)P magnetic resonance spectroscopy throughout both tests. During the maximal contractions, force production fell from 213 +/- 33 N to reach a plateau in the last 30 s of the test at 100 +/- 20 N. The muscle metabolic responses at the end of each test were substantial, but not different between conditions: [PCr] was reduced (to 21 +/- 12 and 17 +/- 7% of baseline for maximal and submaximal contractions, respectively; P = 0.17), [P(i)] was elevated (to 364 +/- 98 and 363 +/- 135% of baseline, respectively; P = 0.98) and pH reduced (to 6.64 +/- 0.16 and 6.69 +/- 0.17, respectively; P = 0.43). The [H(2)PO(4)()] was also elevated at the end of both tests (to 607 +/- 252 and 556 +/- 269% of baseline, respectively; P = 0.22). These data suggest that the exercise-induced metabolic perturbations contributing to force depression in all-out exercise are the same as those contributing to task failure during submaximal contractions.
Abstract.
Author URL.
2009
Benjamin N, Bailey SJ, Vanhatalo A, Winyard P, Jones AM (2009). Beware of the pickle: health effects of nitrate intake Reply.
JOURNAL OF APPLIED PHYSIOLOGY,
107(5), 1678-1678.
Author URL.
Bailey SJ, Winyard P, Vanhatalo A, Blackwell JR, Dimenna FJ, Wilkerson DP, Tarr J, Benjamin N, Jones AM (2009). Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans.
J Appl Physiol (1985),
107(4), 1144-1155.
Abstract:
Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans.
Pharmacological sodium nitrate supplementation has been reported to reduce the O2 cost of submaximal exercise in humans. In this study, we hypothesized that dietary supplementation with inorganic nitrate in the form of beetroot juice (BR) would reduce the O2 cost of submaximal exercise and enhance the tolerance to high-intensity exercise. In a double-blind, placebo (PL)-controlled, crossover study, eight men (aged 19-38 yr) consumed 500 ml/day of either BR (containing 11.2 +/- 0.6 mM of nitrate) or blackcurrant cordial (as a PL, with negligible nitrate content) for 6 consecutive days and completed a series of "step" moderate-intensity and severe-intensity exercise tests on the last 3 days. On days 4-6, plasma nitrite concentration was significantly greater following dietary nitrate supplementation compared with PL (BR: 273 +/- 44 vs. PL: 140 +/- 50 nM; P < 0.05), and systolic blood pressure was significantly reduced (BR: 124 +/- 2 vs. PL: 132 +/- 5 mmHg; P < 0.01). During moderate exercise, nitrate supplementation reduced muscle fractional O2 extraction (as estimated using near-infrared spectroscopy). The gain of the increase in pulmonary O2 uptake following the onset of moderate exercise was reduced by 19% in the BR condition (BR: 8.6 +/- 0.7 vs. PL: 10.8 +/- 1.6 ml.min(-1).W(-1); P < 0.05). During severe exercise, the O2 uptake slow component was reduced (BR: 0.57 +/- 0.20 vs. PL: 0.74 +/- 0.24 l/min; P < 0.05), and the time-to-exhaustion was extended (BR: 675 +/- 203 vs. PL: 583 +/- 145 s; P < 0.05). The reduced O2 cost of exercise following increased dietary nitrate intake has important implications for our understanding of the factors that regulate mitochondrial respiration and muscle contractile energetics in humans.
Abstract.
Author URL.
Vanhatalo A, Jones AM (2009). Influence of creatine supplementation on the parameters of the "all-out critical power test".
J EXERC SCI FIT,
7(1), 9-17.
Abstract:
Influence of creatine supplementation on the parameters of the "all-out critical power test"
We tested the hypotheses that creatine loading would result in no alteration in critical power (CP) or the total work done > CP (W') as estimated from a novel 3-minute all-out cycling protocol. Seven habitually active male subjects completed 3-minute all-out tests against fixed resistance on an electrically-braked cycle ergometer after a 5-day dietary supplementation with 20 g. d(-1) of a glucose placebo (PL) and the same dose of creatine monohydrate (CR). The CP was estimated from the mean power output over the final 30 seconds of the test and the W' was estimated as the power-time integral above the end-test power output. Creatine supplementation resulted in a significant increase in body mass (from 80.4 +/- 9.2 kg to 81.5 +/- 9.5 kg; p < 0.05), whereas the body mass was not different after placebo supplementation (80.3 +/- 9.3 kg; p > 0.05). There were no differences in the power outputs measured during the 3-minute all-out tests Following PL and CR supplementation (CP-PL: 252 +/- 30 W vs. CR: 255 +/- 28 W p > 0.05; W'-PL: 19.4 +/- 3.5 kJ vs. CR: 19.2 +/- 3.4 kJ, p > 0.05; total work done-PL: 64.8 +/- 4.9 kJ vs. CR: 65.0 +/- 4.9 kJ, p > 0.05). Creatine loading had no ergogenic effect on the CP measured using the novel all-out protocol. in contrast to earlier studies which established the power-duration relationship using the conventional protocol, the finite work capacity > CP (W') for all-out exercise was not enhanced by creatine loading. [J Exerc Sci Fit. Vol 7. No 1. 9-17. 2009]
Abstract.
Vanhatalo A, Jones AM (2009). Influence of prior sprint exercise on the parameters of the 'all-out critical power test' in men.
Exp Physiol,
94(2), 255-263.
Abstract:
Influence of prior sprint exercise on the parameters of the 'all-out critical power test' in men.
We tested the hypothesis that a prior 30 s sprint exercise bout would significantly reduce the curvature constant (W') but not the power-asymptote (critical power, CP) of the power-duration relationship as assessed using a novel 3 min all-out cycling test. Seven physically active male subjects completed the 3 min all-out test on three occasions in random order: following no prior sprint exercise (control, C); following a 30 s sprint and a 2 min recovery (S2); and following a 30 s sprint and a 15 min recovery period (S15). The CP was estimated from the mean power output sustained over the final 30 s of the test and the W' was estimated as the power-time integral above the end-test power. There were no significant differences in the estimated CP between the control 3 min all-out trial and the two prior sprint conditions (C, 235 +/- 44 W; S2, 223 +/- 46 W; and S15, 232 +/- 50 W; P > 0.05; coefficients of variation 2, 3 and 6% for C-S2, C-S15 and S2-S15, respectively). However, the W' in S2 (16.5 +/- 3.3 kJ) was significantly lower than in C (20.8 +/- 3.9 kJ) and S15 (21.2 +/- 4.5 kJ; P < 0.05). The total work done was lower in S2 than in the other conditions (S2, 56.4 +/- 7.2 kJ; C, 63.5 +/- 6.6 kJ; and S15, 63.0 +/- 6.0 kJ; P < 0.05). The W', but not the CP, is sensitive to a bout of prior sprint exercise which would be expected to result in significant muscle phosphocreatine depletion. These findings support the fundamental principles of the power-duration relationship as applied to all-out exercise.
Abstract.
Author URL.
Bailey SJ, Vanhatalo A, Wilkerson DP, Dimenna FJ, Jones AM (2009). Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance.
J Appl Physiol (1985),
107(6), 1743-1756.
Abstract:
Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance.
It has been suggested that a prior bout of high-intensity exercise has the potential to enhance performance during subsequent high-intensity exercise by accelerating the O(2) uptake (Vo(2)) on-response. However, the optimal combination of prior exercise intensity and subsequent recovery duration required to elicit this effect is presently unclear. Eight male participants, aged 18-24 yr, completed step cycle ergometer exercise tests to 80% of the difference between the preestablished gas exchange threshold and maximal Vo(2) (i.e. 80%Delta) after no prior exercise (control) and after six different combinations of prior exercise intensity and recovery duration: 40%Delta with 3 min (40-3-80), 9 min (40-9-80), and 20 min (40-20-80) of recovery and 70%Delta with 3 min (70-3-80), 9 min (70-9-80), and 20 min (70-20-80) of recovery. Overall Vo(2) kinetics were accelerated relative to control in all conditions except for 40-9-80 and 40-20-80 conditions as a consequence of a reduction in the Vo(2) slow component amplitude; the phase II time constant was not significantly altered with any prior exercise/recovery combination. Exercise tolerance at 80%Delta was improved by 15% and 30% above control in the 70-9-80 and 70-20-80 conditions, respectively, but was impaired by 16% in the 70-3-80 condition. Prior exercise at 40%Delta did not significantly influence exercise tolerance regardless of the recovery duration. These data demonstrate that prior high-intensity exercise ( approximately 70%Delta) can enhance the tolerance to subsequent high-intensity exercise provided that it is coupled with adequate recovery duration (>or=9 min). This combination presumably optimizes the balance between preserving the effects of prior exercise on Vo(2) kinetics and providing sufficient time for muscle homeostasis (e.g. muscle phosphocreatine and H(+) concentrations) to be restored.
Abstract.
Author URL.
Benjamin N, Bailey SJ, Vanhatalo A, Winyard P, Jones AM (2009). Reply to Derave and Taes. Journal of Applied Physiology, 107(5).
2008
Vanhatalo A, Doust JH, Burnley M (2008). A 3-min all-out cycling test is sensitive to a change in critical power.
Med Sci Sports Exerc,
40(9), 1693-1699.
Abstract:
A 3-min all-out cycling test is sensitive to a change in critical power.
PURPOSE: the aim of this investigation was to test the hypothesis that a 3-min all-out cycling test would detect a change in critical power (CP) after a 4-wk interval training intervention. METHODS: Nine habitually active subjects completed a ramp test, two 3-min all-out tests to establish the end power (EP) and the work done above EP (WEP), and three predicting trials to establish CP and W' using the work-time model (W = CPt + W'). After 12 supervised high-intensity interval training sessions over 4 wk, subjects repeated the testing procedures. RESULTS: the CP increased in all subjects after training (pretraining: 230 +/- 53 W; posttraining: 255 +/- 50 W; t8 = 7.47, P < 0.001), with no statistically significant effect on the W' (pretraining: 17.2 +/- 4.2 kJ; posttraining: 15.5 +/- 3.8 kJ; t8 = 2.03, P = 0.08). The all-out test EP was increased after training from 225 +/- 52 W to 248 +/- 46 W (t8 = 6.26, P < 0.001). The EP and CP estimates before and after training were not different and were highly correlated (pretraining: r = 0.96, P < 0.001; posttraining: r = 0.95, P < 0.001). In addition, the increase in EP was correlated with (r = 0.77, P = 0.016) and not different from (t8 = 0.60, P = 0.57) the increase in CP. There was no change in the WEP from pretraining to posttraining (t8 = 1.89, P = 0.10). CONCLUSIONS: the present study shows that the 3-min all-out test closely estimates CP across a wide range of aerobic fitness and is sensitive to training-induced changes in CP.
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Dekerle J, Vanhatalo A, Burnley A (2008). Determination of critical power from a single test.
SCIENCE & SPORTS,
23(5), 231-238.
Abstract:
Determination of critical power from a single test
Aims. - Determination of critical power (CP) from a single test.Current knowledge. - Recent research has been conducted on the utility of all-out exercise to identify parameters of physiological function. This has led to the development of a protocol that would provide a means of measuring CP, that is, the lower boundary for severe exercise, in a single test. Indeed, our recent findings highlight that all-out exercise of 90 s (as the "Wingate" test) are too short for CP to be attained at the end of the exercise while the end power of a 3-min test has been shown to equal CP the present review presents the methodological considerations to address prior to prolonged all-out exercise testing on cycle ergometers.Prospects. - We conclude by considering the possible applications of our findings to sports performance and the directions for future research in this area. (C) 2008 Elsevier Masson SAS. All rights reserved.
Abstract.
Jones AM, Wilkerson DP, Vanhatalo A, Burnley M (2008). Influence of pacing strategy on O2 uptake and exercise tolerance.
Scand J Med Sci Sports,
18(5), 615-626.
Abstract:
Influence of pacing strategy on O2 uptake and exercise tolerance.
Seven male subjects completed cycle exercise bouts to the limit of tolerance on three occasions: (1) at a constant work rate (340+/-57 W; even-pace strategy; ES); (2) at a work rate that was initially 10% lower than that in the ES trial but which then increased with time such that it was 10% above that in the ES trial after 120 s of exercise (slow-start strategy; SS); and, (3) at a work rate that was initially 10% higher than that in the ES trial but which then decreased with time such that it was 10% below that in the ES trial after 120 s of exercise (fast-start strategy; FS). The expected time to exhaustion predicted from the pre-established power-time relationship was 120 s in all three conditions. However, the time to exhaustion was significantly greater (P
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Vanhatalo A, Doust JH, Burnley M (2008). Robustness of a 3 min all-out cycling test to manipulations of power profile and cadence in humans.
Exp Physiol,
93(3), 383-390.
Abstract:
Robustness of a 3 min all-out cycling test to manipulations of power profile and cadence in humans.
The purpose of this study was to assess whether end-test power output (EP, synonymous with 'critical power') and the work done above EP (WEP) during a 3 min all-out cycling test against a fixed resistance were affected by the manipulation of cadence or pacing. Nine subjects performed a ramp test followed, in random order, by three cadence trials (in which flywheel resistance was manipulated to achieve end-test cadences which varied by approximately 20 r.p.m.) and two pacing trials (30 s at 100 or 130% of maximal ramp test power, followed by 2.5 min all-out effort against standard resistance). End-test power output was calculated as the mean power output over the final 30 s and the WEP as the power-time integral over 180 s for each trial. End-test power output was unaffected by reducing cadence below that of the 'standard test' but was reduced by approximately 10 W on the adoption of a higher cadence [244 +/- 41 W for high cadence (at an end-test cadence of 95 +/- 7 r.p.m.), 254 +/- 40 W for the standard test (at 88 +/- 6 r.p.m.) and 251 +/- 38 W for low cadence (at 77 +/- 5 r.p.m.)]. Pacing over the initial 30 s of the test had no effect on the EP or WEP estimates in comparison with the standard trial. The WEP was significantly higher in the low cadence trial (16.2 +/- 4.4 kJ) and lower in the high cadence trial (12.9 +/- 3.6 kJ) than in the standard test (14.2 +/- 3.7 kJ). Thus, EP is robust to the manipulation of power profile but is reduced by adopting cadences higher than 'standard'. While the WEP is robust to initial pacing applied, it is sensitive to even relatively minor changes in cadence.
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2007
Vanhatalo A, Burnley M, Doust JH (2007). Determination of Critical Power Using a 3-Minute All-Out Cycling Test. Medicine & Science in Sports & Exercise, 39(3), 548-555.
Vanhatalo A, Doust JH, Burnley M (2007). Determination of critical power using a 3-min all-out cycling test.
Med Sci Sports Exerc,
39(3), 548-555.
Abstract:
Determination of critical power using a 3-min all-out cycling test.
PURPOSE: We tested the hypothesis that the power output attained at the end of a 3-min all-out cycling test would be equivalent to critical power. METHODS: Ten habitually active subjects performed a ramp test, two 3-min all-out tests against a fixed resistance to establish the end-test power (EP) and the work done above the EP (WEP), and five constant-work rate tests to establish the critical power (CP) and the curvature constant parameter (W') using the work-time and 1/time models. RESULTS: the power output in the 3-min trial declined to a steady level within 135 s. The EP was 287 +/- 55 W, which was not significantly different from, and highly correlated with, CP (287 +/- 56 W; P = 0.37, r = 0.99). The standard error for the estimation of CP using EP was approximately 6 W, and in 8 of 10 cases, EP agreed with CP to within 5 W. Similarly, the WEP derived from the 3-min test (15.0 +/- 4.7 kJ) was not significantly different from, and correlated with, W' (16.0 +/- 3.8 kJ; P = 0.35; r = 0.84). CONCLUSIONS: During a 3-min all-out cycling test, power output declined to a stable value in approximately the last 45 s, and this power output was not significantly different from the independently measured critical power.
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2006
Burnley M, Doust JH, Vanhatalo A (2006). A 3-min all-out test to determine peak oxygen uptake and the maximal steady state.
Med Sci Sports Exerc,
38(11), 1995-2003.
Abstract:
A 3-min all-out test to determine peak oxygen uptake and the maximal steady state.
PURPOSE: We tested the hypothesis that a 3-min all-out cycling test would provide a measure of peak oxygen uptake (VO2peak) and estimate the maximal steady-state power output. METHODS: Eleven habitually active subjects performed a ramp test, three 3-min all-out tests against a fixed resistance, and two further submaximal tests lasting up to 30 min, 15 W below or above the power output attained in the last 30 s of the 3-min test (the end-test power). RESULTS: the VO2peak measured during the 3-min all-out test (mean +/- SD: 3.78 +/- 0.68 L x min(-1)) was not different from that of the ramp test (3.84 +/- 0.79 L x min(-1); P = 0.75). The end-test power (257 +/- 49 W) was significantly lower than that at the end of the ramp test (368 +/- 73 W) and significantly higher than the power at the gas exchange threshold (169 +/- 55 W; P < 0.001). Nine subjects were able to complete 30 min of exercise at 15 W below the end-test power, and seven of these did so with a steady-state blood [lactate] and VO2 response profile. In contrast, when subjects exercised at 15 W above the end-test power, blood [lactate] and VO2 rose inexorably until exhaustion, which occurred in approximately 13 +/- 7 min. CONCLUSIONS: These data suggest that a 3-min all-out exercise test can be used to establish VO2peak and to estimate the maximal steady state.
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