Effects of low and high dietary nitrate intake on human saliva, plasma and skeletal muscle nitrate and nitrite concentrations and their functional consequences.

Dietary nitrate (NO) supplementation has been shown to reduce blood pressure (BP), improve exercise performance, and alter the oral microbiome. Following a "control" diet (CON), we manipulated dietary NO intake to examine the effect of a short-term (7-day) low NO diet (LOW) followed by a 3-day high NO diet (HIGH), compared to a 7-day standard (STD) NO diet followed by HIGH, on saliva, plasma, and muscle [NO] and nitrite ([NO]), BP, and cycling exercise performance in healthy young adults. We also examined the effect of LOW on the oral microbiome.

Relationships between nitric oxide biomarkers and physiological outcomes following dietary nitrate supplementation.

Dietary nitrate (NO) supplementation can increase nitric oxide (NO) bioavailability, reduce blood pressure (BP) and improve muscle contractile function in humans. Plasma nitrite concentration (plasma [NO]) is the most oft-used biomarker of NO bioavailability. However, it is unclear which of several NO biomarkers (NO, NO, S-nitrosothiols (RSNOs)) in plasma, whole blood (WB), red blood cells (RBC) and skeletal muscle correlate with the physiological effects of acute and chronic dietary NO supplementation.

Reduction in blood pressure following acute dietary nitrate ingestion is correlated with increased red blood cell S-nitrosothiol concentrations.

Dietary nitrate (NO) supplementation can enhance nitric oxide (NO) bioavailability and lower blood pressure (BP) in humans. The nitrite concentration ([NO]) 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 NO.

N-labeled dietary nitrate supplementation increases human skeletal muscle nitrate concentration and improves muscle torque production.

Aim: Dietary nitrate (NO ) supplementation increases nitric oxide bioavailability and can enhance exercise performance. We investigated the distribution and metabolic fate of ingested NO at rest and during exercise with a focus on skeletal muscle.

Methods: In a randomized, crossover study, 10 healthy volunteers consumed 12.

Accounting for Dynamic Changes in the Power-Duration Relationship Improves the Accuracy of W' Balance Modeling.

Purpose: This study aimed 1) to examine the accuracy with which W' reconstitution (W' REC ) is estimated by the W' balance (W' BAL ) models after a 3-min all-out cycling test (3MT), 2) to determine the effects of a 3MT on the power-duration relationship, and 3) to assess whether accounting for changes in the power-duration relationship during exercise improved estimates of W' REC .

Methods: The power-duration relationship and the actual and estimated W' REC were determined for 12 data sets extracted from our laboratory database where participants had completed two 3MT separated by 1-min recovery (i.e.

Time course of human skeletal muscle nitrate and nitrite concentration changes following dietary nitrate ingestion.

Dietary nitrate (NO) ingestion can be beneficial for health and exercise performance. Recently, based on animal and limited human studies, a skeletal muscle NO reservoir has been suggested to be important in whole body nitric oxide (NO) homeostasis. The purpose of this study was to determine the time course of changes in human skeletal muscle NO concentration ([NO]) following the ingestion of dietary NO.

Highly Cushioned Shoes Improve Running Performance in Both the Absence and Presence of Muscle Damage.

Purpose: We tested the hypotheses that a highly cushioned running shoe (HCS) would 1) improve incremental exercise performance and reduce the oxygen cost (Oc) of submaximal running, and 2) attenuate the deterioration in Oc elicited by muscle damage consequent to a downhill run.

Methods: Thirty-two recreationally active participants completed an incremental treadmill test in an HCS and a control running shoe (CON) for the determination of Oc and maximal performance. Subsequently, participants were pair matched and randomly assigned to one of the two footwear conditions to perform a moderate-intensity running bout before and 48 h after a 30-min downhill run designed to elicit muscle damage.

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.

The Anthropometry of Economical Running.

Unlabelled: The influence of anthropometry and body composition on running economy is unclear, with previous investigations involving small relatively homogeneous groups of runners and limited anthropometric/composition measurements.

Purpose: To comprehensively investigate the relationships of anthropometry and body composition with running economy within a large heterogeneous sample of runners.

Methods: Eighty-five runners (males [M], n = 45; females [F], n = 40), of diverse competitive standard, performed a discontinuous protocol of incremental treadmill running (4-min stages, 1 km·h increments) to establish locomotory energy cost (LEc) of running at submaximal speeds (averaged across 10-12 km·h; the highest common speed < lactate turnpoint).

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.

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; < 0.

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.

Road cycle TT performance: Relationship to the power-duration model and association with FTP.

Purpose: To determine the accuracy of critical power (CP) and W' (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.

The Effects of β-Alanine Supplementation on Muscle pH and the Power-Duration Relationship during High-Intensity Exercise.

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').

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.

Is There an Optimal Speed for Economical Running?

The influence of running speed and sex on running economy is unclear and may have been confounded by measurements of oxygen cost that do not account for known differences in substrate metabolism, across a limited range of speeds, and differences in performance standard. Therefore, this study assessed the energy cost of running over a wide range of speeds in high-level and recreational runners to investigate the effect of speed (in absolute and relative terms) and sex (men vs women of equivalent performance standard) on running economy. To determine the energy cost (kcal · kg · km) of submaximal running, speed at lactate turn point (sLTP), and maximal rate of oxygen uptake, 92 healthy runners (high-level men, n = 14; high-level women, n = 10; recreational men, n = 35; recreational women, n = 33) completed a discontinuous incremental treadmill test.

Maximal Oxygen Uptake Is Achieved in Hypoxia but Not Normoxia during an Exhaustive Severe Intensity Run.

Highly aerobically trained individuals are unable to achieve maximal oxygen uptake ([Formula: see text]) during exhaustive running lasting ~2 min, instead [Formula: see text] plateaus below [Formula: see text] after ~1 min. Hypoxia offers the opportunity to study the ([Formula: see text]) response to an exhaustive run relative to a hypoxia induced reduction in [Formula: see text]. The aim of this study was to explore whether there is a difference in the percentage of [Formula: see text] achieved (during a 2 min exhaustive run) in normoxia and hypoxia.

Running Technique is an Important Component of Running Economy and Performance.

Unlabelled: Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated.

Purpose: This study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance.

Methods: Ninety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km·h increments).

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 (T) 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 T, a heavy-intensity (HVY; GET) CWR test until T, and a moderate-intensity (MOD; 0.

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: ) SIT and [Formula: see text]-depleted beetroot juice as a placebo (SIT+PL); ) SIT and [Formula: see text]-rich beetroot juice (~13 mmol [Formula: see text]/day; SIT+BR); or ) 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 ( < 0.

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 mechanistic bases of the power-time relationship: muscle metabolic responses and relationships to muscle fibre type.

Key Points: The power-asymptote (critical power; CP) of the hyperbolic power-time relationship for high-intensity exercise defines a threshold between steady-state and non-steady-state exercise intensities and the curvature constant (W') indicates a fixed capacity for work >CP that is related to a loss of muscular efficiency. The present study reports novel evidence on the muscle metabolic underpinnings of CP and W' during whole-body exercise and their relationships to muscle fibre type. We show that the W' is not correlated with muscle fibre type distribution and that it represents an elevated energy contribution from both oxidative and glycolytic/glycogenolytic metabolism.

Effects of Priming and Pacing Strategy on Oxygen-Uptake Kinetics and Cycling Performance.

Purpose: To assess whether combining prior "priming" exercise with an all-out pacing strategy is more effective at improving oxygen-uptake (VO2) kinetics and cycling performance than either intervention administered independently.

Methods: Nine men completed target-work cycling performance trials using a self-paced or all-out pacing strategy with or without prior severe-intensity (70%Δ) priming exercise. Breath-by-breath pulmonary VO2 and cycling power output were measured during all trials.

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.