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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 15N‐labeled potassium nitrate (K15NO3; 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 15N‐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 < 0.001) and 3‐h, with almost all of the increase being 15N‐labeled. There was a significant reduction in 15N‐labeled muscle [NO3−] from pre‐ to post‐exercise. Relative to PLA, mean muscle torque production was ~7% greater during the first 18 contractions following NIT. This improvement in torque was correlated with the pre‐exercise 15N‐labeled muscle [NO3−] and the magnitude of decline in 15N‐labeled muscle [NO3−] during exercise (r = 0.66 and r = 0.62, respectively; p < 0.01). Conclusion: This study shows, for the first time, that skeletal muscle rapidly takes up dietary NO3−, the elevated muscle [NO3−] following NO3− ingestion declines during exercise, and muscle NO3− dynamics are associated with enhanced torque production during maximal intermittent muscle contractions. [ABSTRACT FROM AUTHOR]

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., control [C-3MT] and fatigued [F-3MT]). Results: Actual W′REC (6.3 ± 1.4 kJ) was significantly overestimated by the W′BAL·ODE (9.8 ± 1.3 kJ; P < 0.001) and the W′BAL·MORTON (16.9 ± 2.6 kJ; P < 0.001) models but was not significantly different to the estimate provided by the W′BAL·INT (7.5 ± 1.5 kJ; P > 0.05) model. End power (EP) was 7% lower in the F-3MT (263 ± 40 W) compared with the C-3MT (282 ± 44 W; P < 0.001), and work done above EP (WEP) was 61% lower in the F-3MT (6.3 ± 1.4 kJ) compared with the C-3MT (16.9 ± 3.2 kJ). The size of the error in the estimated W′REC was correlated with the reduction in WEP for the W′BAL·INT and W′BAL·ODE models (both r > −0.74, P < 0.01) but not the W′BAL·MORTON model (r = −0.18, P > 0.05). Accounting for the changes in the power–duration relationship improved the accuracy of the W′BAL·ODE and W′BAL·MORTON, but they remained significantly different to actual W′REC. Conclusions: These findings demonstrate that the power–duration relationship is altered after a 3MT, and accounting for these changes improves the accuracy of the W′BAL·ODE and the W′BAL·MORTON, but not W′BAL·INT models. These results have important implications for the design and use of mathematical models describing the energetics of exercise performance. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether oxygen-uptake (...) 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 ... 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 ... mean response time (MRT) was lower (indicative of faster ... 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 < .05), with the ... MRT also lower in the all-out unprimed than the self-paced unprimed and self-paced primed trials (P < .05). Trial-completion time was shorter (performance was enhanced) in the all-out primed trial (402 ± 14 s) than in the all-out unprimed (408 ± 14 s), self-paced unprimed (411 ± 16 s), and self-paced primed (411 ± 19 s) trials (P < .05), with no differences between the latter 3 trials. Conclusions: The findings from this study suggest that combining severe-intensity priming exercise with a short-duration all-out starting strategy can expedite the adjustment of ... and lower completion time during a cycling performance trial to a greater extent than either intervention administered independently. These results might have implications for optimizing performance in short-duration high-intensity competitive events such as a 4-km cycling time trial. [ABSTRACT FROM AUTHOR]

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-1 ⋅ km-1) 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. There were no sex-specific differences in the energy cost of running for the recreational or high-level runners when compared at absolute or relative running speeds (P > .05). The absolute and relative speed--energy cost relationships for the high-level runners demonstrated a curvilinear U shape with a nadir reflecting the most economical speed at 13 km/h or 70% sLTP. The high-level runners were more economical than the recreational runners at all absolute and relative running speeds (P < .05). These findings demonstrate that there is an optimal speed for economical running, there is no sex-specific difference, and high-level endurance runners exhibit better running economy than recreational endurance runners. [ABSTRACT FROM AUTHOR]

Purpose: To assess whether combining prior "priming" exercise with an all-out pacing strategy is more effective at improving oxygen-uptake (...O2) 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. Results: Compared with the self-paced unprimed control trial (22 ± 5 s), the VO2 mean response time (MRT) was shorter (...O2 kinetics were faster) with all-out pacing (17 ± 4 s) and priming (17 ± 3 s), with the lowest ...O2 MRT observed when all-out pacing and priming were combined (15 ± 4 s) (P < .05). However, total O2 consumed and end-exercise ...O2 were only higher than the control condition in the primed trials (P < .05). Similarly, cycling performance was improved compared with control (98 ±11 s) in the self-paced primed (93 ± 8 s) and all-out primed (92 ± 8 s) trials (P < .05) but not the all-out unprimed trial (97 ± 5 s; P > .05). Conclusions: These findings suggest that combining an all-out start with severe-intensity priming exercise additively improves VO2 MRT but not total O2 consumption and cycling performance since these were improved by a similar magnitude in both primed trials relative to the self-paced unprimed control condition. Therefore, these results support the use of priming exercise as a precompetition intervention to improve oxidative metabolism and performance during short-duration high-intensity cycling exercise, independent of the pacing strategy adopted. [ABSTRACT FROM AUTHOR]

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−1 increments) to establish locomotory energy cost (LEc) of running at submaximal speeds (averaged across 10–12 km·h−1; the highest common speed < lactate turnpoint). Measurements of anthropometry, including segment lengths, perimeters, masses and moments of inertia, and body composition were obtained using tape-based measurements and dual-energy x-ray absorptiometry. Results: Absolute LEc (ABSLEc, kcal·km−1) was positively correlated with 21 (of 27) absolute anthropometric variables in both male and female cohorts. Multiple-regression analyses revealed that one variable (mean perimeter z score) explained 49.4% (M) and 68.9% (F) of the variance in ABSLEc. Relative LEc (RELLEc, kcal·kg−1·km−1) was also correlated with five (M) and seven (F) normalized anthropometric variables, and regression analyses explained 31.6% (M; percentage bone mass and normalized hip perimeter) and 33.3% (F, normalized forearm perimeter) of the variance in RELLEc. Conclusions: These findings provide novel and robust evidence that anthropometry and body composition variables, predominantly indicative of relative slenderness, explain a considerable proportion of the variance in running economy (i.e., more slender, lower energy cost). We, therefore, recommend that runners and coaches are attentive to relative slenderness in selecting and training athletes with the aim of enhancing running economy, and improving distance running performance. [ABSTRACT FROM AUTHOR]

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 < 0.01). CP and FTP were not significantly different (275 ± 40 W vs. 278 ± 42 W, 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 FROM AUTHOR]

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) andV̇O2max. Ten club-level male cyclists (mean±SD: age 33.8±8.2 y, body mass 73.8±4.3 kg,V̇O2max 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<0.01) and total work done during the all-out test (70.9±6.5 kJ;r=−0.86,P<0.01), the ramp incremental test peak power (433±30 W;r=−0.75,P<0.05) and the RCP (315±29 W;r=−0.68,P<0.05), but not with GET (151±32 W;r=−0.21) or theV̇O2max (4.41±0.25 L·min−1;r=−0.60). These data provide evidence for the predictive validity and practical performance relevance of the 3-min all-out test. The 3-min all-out test CP may represent a useful addition to the battery of tests employed by applied sport physiologists or coaches to track fitness and predict performance in atheletes. [ABSTRACT FROM PUBLISHER]