Effects of Two Hours of Heavy-Intensity Exercise on the Power–Duration Relationship

Clark, Ida E.; Vanhatalo, Anni; Bailey, Stephen J.; Wylie, Lee J.; Kirby, Brett S.; Wilkins, Brad W.; Jones, Andrew M.

doi:10.1249/mss.0000000000001601

Cited by 47 publications

(65 citation statements)

References 28 publications

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“…However, the present study demonstrates that exercising for 30 minutes at MLSS, with elevated but stable metabolic responses (ie, [La − ] b and V.O 2 ), results in a significant reduction in subsequent exercise performance. This is in agreement with a recent study showing that exercising for 2 hours in the heavy‐intensity domain (at an intensity even lower than the one used in the present study) reduced subsequent work capacity carried in the severe‐intensity domain …”

Section: Discussionsupporting

confidence: 94%

“…This is in agreement with a recent study showing that exercising for 2 hours in the heavyintensity domain (at an intensity even lower than the one used in the present study) reduced subsequent work capacity carried in the severe-intensity domain. 39 In addition to this, the present study found a disproportionate decrement in time-to-exhaustion performance (~50%) after exercising at MLSS p+10 which was accompanied by a decrease in V .…”

Section: Performance Implications Of Exercising At a Po Associated supporting

confidence: 70%

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Metabolic and performance‐related consequences of exercising at and slightly above MLSS

Iannetta

Inglis

Fullerton

et al. 2018

Scandinavian Med Sci Sports

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Exercising at the maximal lactate steady state (MLSS) results in increased but stable metabolic responses. We tested the hypothesis that even a slight increase above MLSS (10 W), by altering the metabolic steady state, would reduce exercise performance capacity. Eleven trained men in our study performed: one ramp-incremental tests; two to four 30-minute constant-load cycling exercise trials to determine the PO at MLSS (MLSS ), and ten watts above MLSS (MLSS ), which were immediately followed by a time-to-exhaustion test; and a time-to-exhaustion test with no-prior exercise. Pulmonary O uptake V.O ) and blood lactate concentration ([La ] ) as well as local muscle O extraction ([HHb]) and muscle activity (EMG) of the vastus lateralis (VL) and rectus femoris (RF) muscles were measured during the testing sessions. When exercising at MLSS , although V.O was stable, there was an increase in ventilatory responses and EMG activity, along with a non-stable [La ] response (P < 0.05). The [HHb] of VL muscle achieved its apex at MLSS with no additional increase above this intensity, whereas the [HHb] of RF progressively increased during MLSS and achieved its apex during the time-to-exhaustion trials. Time-to-exhaustion performance was decreased after exercising at MLSS (37.3 ± 16.4%) compared to the no-prior exercise condition, and further decreased after exercising at MLSS (64.6 ± 6.3%) (P < 0.05). In summary, exercising for 30 min slightly above MLSS led to significant alterations of metabolic responses which disproportionately compromised subsequent exercise performance. Furthermore, the [HHb] signal of VL seemed to achieve a "ceiling" at the intensity of exercise associated with MLSS.

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Section: Discussionsupporting

confidence: 94%

Section: Performance Implications Of Exercising At a Po Associated supporting

confidence: 70%

Metabolic and performance‐related consequences of exercising at and slightly above MLSS

Iannetta

Inglis

Fullerton

et al. 2018

Scandinavian Med Sci Sports

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“…Moreover, CP is correlated with indices of muscle capillary density, particularly around type I muscle fibers ( 13 ). Most recently, it has been shown that CP declines after prolonged exercise ( 32 ), a decline that is blunted by ingestion of carbohydrates ( 33 ). Thus, CT/CP seems to be determined, in part, by muscle fiber properties and the supply of substrates and O 2 to them, and therefore, the mechanism(s) responsible for the phase transition we propose here likely involves these factors too.…”

Section: Discussionmentioning

confidence: 99%

Physiological Evidence That the Critical Torque Is a Phase Transition, Not a Threshold

Pethick¹,

Winter²

2020

Medicine &Amp; Science in Sports &Amp; Exercise

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Introduction Distinct physiological responses to exercise occur in the heavy- and severe-intensity domains, which are separated by the critical power or critical torque (CT). However, how the transition between these intensity domains actually occurs is not known. We tested the hypothesis that CT is a sudden threshold, with no gradual transition from heavy- to severe-intensity behavior within the confidence limits associated with the CT. Methods Twelve healthy participants performed four exhaustive severe-intensity trials for the determination of CT, and four 30-min trials in close proximity to CT (one or two SE above or below each participant’s CT estimate; CT − 2, CT − 1, CT + 1, CT + 2). Muscle O 2 uptake, rectified electromyogram, and torque variability and complexity were monitored throughout each trial, and maximal voluntary contractions (MVC) with femoral nerve stimulation were performed before and after each trial to determine central and peripheral fatigue responses. Results The rates of change in fatigue-related variables, muscle O 2 uptake, electromyogram amplitude, and torque complexity were significantly faster in the severe trials compared with CT − 2. For example, the fall in MVC torque was −1.5 ± 0.8 N·m·min −1 in CT − 2 versus –7.9 ± 2.5 N·m·min −1 in the lowest severe-intensity trial ( P < 0.05). Individual analyses showed a low frequency of severe responses even in the circa-CT trials ostensibly above the CT, but also the rare appearance of severe-intensity responses in all circa-CT trials. Conclusions These data demonstrate that the transition between heavy- and severe-intensity exercise occurs gradually rather than suddenly.

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“…; Clark et al. ). Hence, for the criterion test to be accepted as valid, there must be no indication of pacing in the speed or power output profile (i.e.…”

Section: Considerations For the Accurate Assessment Of The Power‐duramentioning

confidence: 98%

The maximal metabolic steady state: redefining the ‘gold standard’

et al. 2019

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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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Effects of Two Hours of Heavy-Intensity Exercise on the Power–Duration Relationship

Cited by 47 publications

References 28 publications

Metabolic and performance‐related consequences of exercising at and slightly above MLSS

Metabolic and performance‐related consequences of exercising at and slightly above MLSS

Physiological Evidence That the Critical Torque Is a Phase Transition, Not a Threshold

The maximal metabolic steady state: redefining the ‘gold standard’

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