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"Critical power"

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https://www.readbyqxmd.com/read/28166117/the-respiratory-compensation-point-is-not-a-valid-surrogate-for-critical-power
#1
Jeffrey A Leo, Surendran Sabapathy, Michael J Simmonds, Troy J Cross
PURPOSE: It is unclear whether the respiratory compensation point (RCP) may be used as a valid surrogate for critical power (CP). Accordingly, we sought to determine the measurement agreement between CP and the RCP obtained during incremental cycling of varying ramp slopes. METHODS: Eleven recreationally-active men completed three separate ramp-incremental cycling protocols, where the work rate increment was slow (SR: 15 W[BULLET OPERATOR]min), medium (MR: 30 W[BULLET OPERATOR]min) or fast (FR: 45 W[BULLET OPERATOR]min)...
February 4, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28019724/a-comparison-of-methods-to-estimate-anaerobic-capacity-accumulated-oxygen-deficit-and-w-during-constant-and-all-out-work-rate-profiles
#2
Daniel Muniz-Pumares, Charles Pedlar, Richard Godfrey, Mark Glaister
This study investigated (i) whether the accumulated oxygen deficit (AOD) and curvature constant of the power-duration relationship (W') are different during constant work-rate to exhaustion (CWR) and 3-min all-out (3MT) tests and (ii) the relationship between AOD and W' during CWR and 3MT. Twenty-one male cyclists (age: 40 ± 6 years; maximal oxygen uptake [V̇O2max]: 58 ± 7 ml · kg(-1) · min(-1)) completed preliminary tests to determine the V̇O2-power output relationship and V̇O2max. Subsequently, AOD and W' were determined as the difference between oxygen demand and oxygen uptake and work completed above critical power, respectively, in CWR and 3MT...
December 26, 2016: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28008101/muscle-metabolic-and-neuromuscular-determinants-of-fatigue-during-cycling-in-different-exercise-intensity-domains
#3
Matthew I Black, Andrew M Jones, Jamie R Blackwell, Stephen J Bailey, Lee J Wylie, Sinead T J McDonagh, Christopher Thompson, James Kelly, Paul Sumners, Katya J Mileva, Joanna L Bowtell, Anni Vanhatalo
The lactate or gas exchange threshold (GET) and the 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 males performed a ramp incremental exercise test, 4-5 severe-intensity (SEV; >CP) constant-work-rate (CWR) tests until Tlim, a heavy-intensity (HVY; <CP but >GET) CWR test until Tlim, and a moderate-intensity (MOD; <GET) CWR test until Tlim Muscle biopsies revealed that a similar (P>0...
December 22, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27991483/differing-six-minute-pacing-strategies-effect-anaerobic-contribution-oxygen-uptake-muscle-deoxygenation-and-cycle-performance
#4
John Murray, Michael McCrudden, Juan M Murias, Volker Nolte, Glen R Belfry
BACKGROUND: This study compared an all-out start (AO) to a constant power start strategy (CON) during a 6 min cycle performance on utilization of W ́ (energy above critical power (CP)), muscle deoxygenation (HHb), oxygen uptake (VO2) and performance in recreationally active individuals. The AO strategy was similar to that employed by rowers. METHODS: Eight healthy males (age = 24 ± 3 y) completed a ramp test to fatigue (VO2peak = 4.42 ± 0.54 L∙min-1; peak power = 385 ± 35 W) and a 3-min all-out test to determine CP and the CON work rate...
December 16, 2016: Journal of Sports Medicine and Physical Fitness
https://www.readbyqxmd.com/read/27918663/comparison-of-critical-power-and-w-derived-from-two-or-three-maximal-tests
#5
Len Parker Simpson, Mehdi Kordi
PURPOSE: Typically, accessing the asymptote (Critical Power; CP) and curvature constant (W') parameters of the hyperbolic power-duration relationship requires multiple constant-power, exhaustive exercise trials, spread over several visits. However, more recently single-visit protocols and personal power meters have been used. We investigated the practicality of using a two-trial, single-visit protocol in providing reliable CP & W' estimates. METHODS: 8 trained cyclists underwent 3- and 12-min maximal exercise trials in a single session to derive (2-trial) CP & W' estimates...
December 5, 2016: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/27834562/predicting-critical-power-in-elite-cyclists-questioning-validity-of-the-3-min-all-out-test
#6
Jason C Bartram, Dominic Thewlis, David T Martin, Kevin I Norton
PURPOSE: New applications of the critical power concept, such as the modelling of intermittent work capabilities, are exciting prospects for elite cycling. However, accurate calculation of the required parameters is traditionally time invasive and somewhat impractical. An alternative single test protocol (3-min All-out) has recently been proposed, but validation in an elite population is lacking. The traditional approach for parameter establishment, but with fewer tests, could also prove an acceptable compromise...
November 11, 2016: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/27819154/can-measures-of-critical-power-precisely-estimate-the-maximal-metabolic-steady-state
#7
COMPARATIVE STUDY
Felipe Mattioni Maturana, Daniel A Keir, Kaitlin M McLay, Juan M Murias
Critical power (CP) conceptually represents the highest power output (PO) at physiological steady-state. In cycling exercise, CP is traditionally derived from the hyperbolic relationship of ∼5 time-to-exhaustion trials (TTE) (CPHYP). Recently, a 3-min all-out test (CP3MIN) has been proposed for estimation of CP as well the maximal lactate steady-state (MLSS). The aim of this study was to compare the POs derived from CPHYP, CP3MIN, and MLSS, and the oxygen uptake and blood lactate concentrations at MLSS. Thirteen healthy young subjects (age, 26 ± 3years; mass, 69...
November 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/27806677/power-duration-relationship-physiology-fatigue-and-the-limits-of-human-performance
#8
Mark Burnley, Andrew M Jones
The duration that exercise can be maintained decreases as the power requirements increase. In this review, we describe the power-duration (PD) relationship across the full range of attainable power outputs in humans. We show that a remarkably small range of power outputs is sustainable (power outputs below the critical power, CP). We also show that the origin of neuromuscular fatigue differs considerably depending on the exercise intensity domain in which exercise is performed. In the moderate domain (below the lactate threshold, LT), fatigue develops slowly and is predominantly of central origin (residing in the central nervous system)...
November 3, 2016: European Journal of Sport Science
https://www.readbyqxmd.com/read/27787608/the-constant-work-rate-critical-power-protocol-overestimates-ramp-incremental-exercise-performance
#9
Matthew I Black, Andrew M Jones, James A Kelly, Stephen J Bailey, Anni Vanhatalo
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...
December 2016: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/27782419/structure-and-dynamics-of-binary-liquid-mixtures-near-their-continuous-demixing-transitions
#10
Sutapa Roy, S Dietrich, Felix Höfling
The dynamic and static critical behavior of a family of binary Lennard-Jones liquid mixtures, close to their continuous demixing points (belonging to the so-called model H' dynamic universality class), are studied computationally by combining semi-grand canonical Monte Carlo simulations and large-scale molecular dynamics (MD) simulations, accelerated by graphic processing units (GPU). The symmetric binary liquid mixtures considered cover a variety of densities, a wide range of compressibilities, and various interactions between the unlike particles...
October 7, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27688431/w-expenditure-and-reconstitution-during-severe-intensity-constant-power-exercise-mechanistic-insight-into-the-determinants-of-w
#11
Ryan M Broxterman, Phillip F Skiba, Jesse C Craig, Samuel L Wilcox, Carl J Ade, Thomas J Barstow
The sustainable duration of severe intensity exercise is well-predicted by critical power (CP) and the curvature constant (W'). The development of the W'BAL model allows for the pattern of W' expenditure and reconstitution to be characterized and this model has been applied to intermittent exercise protocols. The purpose of this investigation was to assess the influence of relaxation phase duration and exercise intensity on W' reconstitution during dynamic constant power severe intensity exercise. Six men (24...
October 2016: Physiological Reports
https://www.readbyqxmd.com/read/27686573/knowledge-is-power-issues-of-measuring-training-and-performance-in-cycling
#12
L Passfield, Jg Hopker, S Jobson, D Friel, M Zabala
Mobile power meters provide a valid means of measuring cyclists' power output in the field. These field measurements can be performed with very good accuracy and reliability making the power meter a useful tool for monitoring and evaluating training and race demands. This review presents power meter data from a Grand Tour cyclist's training and racing and explores the inherent complications created by its stochastic nature. Simple summary methods cannot reflect a session's variable distribution of power output or indicate its likely metabolic stress...
August 12, 2016: Journal of Sports Sciences
https://www.readbyqxmd.com/read/27613650/an-integrated-view-on-the-oxygenation-responses-to-incremental-exercise-at-the-brain-the-locomotor-and-respiratory-muscles
#13
REVIEW
Jan Boone, Kristof Vandekerckhove, Ilse Coomans, Fabrice Prieur, Jan G Bourgois
In the past two decades oxygenation responses to incremental ramp exercise, measured non-invasively by means of near-infrared spectroscopy at different locations in the body, have advanced the insights on the underpinning mechanisms of the whole-body pulmonary oxygen uptake ([Formula: see text]) response. In healthy subjects the complex oxygenation responses at the level of locomotor and respiratory muscles, and brain were simplified and quantified by the detection of breakpoints as a deviation in the ongoing response pattern as work rate increases...
December 2016: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/27607973/inhibition-of-multi-filamentation-of-high-power-laser-beams
#14
Rostislav I Grynko, Darshana L Weerawarne, Xiaohui Gao, Houkun Liang, Henry J Meyer, Kyung-Han Hong, Alexander L Gaeta, Bonggu Shim
We experimentally demonstrate the control and complete elimination of multi-filamentation in condensed matter by varying the focusing geometry. In particular, increasing the input beam power enables the extension of the filament length without generating multi-filaments up to 1400 times the critical power in fused silica at an 800 nm wavelength. Furthermore, the generated single filament exhibits spatial solitary wave behavior.
September 1, 2016: Optics Letters
https://www.readbyqxmd.com/read/27607654/picosecond-laser-induced-water-condensation-in-a-cloud-chamber
#15
Haiyi Sun, Yonghong Liu, Jingjing Ju, Ye Tian, Yafeng Bai, Yaoxiang Liu, Shengzhe Du, Cheng Wang, Tiejun Wang, Jiansheng Liu, See Leang Chin, Ruxin Li, Zhizhan Xu
We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament...
September 5, 2016: Optics Express
https://www.readbyqxmd.com/read/27559548/determination-of-critical-power-and-anaerobic-work-capacity-is-one-test-better-than-two-in-response
#16
COMMENT
Haley Bergstrom, Terry Housh
No abstract text is available yet for this article.
May 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27551939/high-intensity-interval-training-in-the-boundaries-of-the-severe-domain-effects-on-sprint-and-endurance-performance
#17
T Turnes, R A de Aguiar, R S de Oliveira Cruz, K Pereira, A F Salvador, F Caputo
In order to compare the effects of two 4-week interval training programs performed at the lower (Critical Power, CP) or at the higher (The highest intensity at which V˙O2max is attained, IHIGH) intensities of the severe exercise domain on sprint and endurance cycling performance, 21 recreationally trained cyclists performed the Wingate Anaerobic Test (WAnT) and a 250-kJ time trial. Accumulated oxygen deficit (AOD), surface electromyography (RMS), and blood lactate kinetics were measured during the WAnT. Subjects were assigned to 105% CP or IHIGH groups...
November 2016: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/27531664/comparison-of-inter-trial-recovery-times-for-the-determination-of-critical-power-and-w-in-cycling
#18
Bettina Karsten, James Hopker, Simon A Jobson, Jonathan Baker, Luca Petrigna, Andreas Klose, Christopher Beedie
: Critical Power (CP) and W' are often determined using multi-day testing protocols. To investigate this cumbersome testing method, the purpose of this study was to compare the differences between the conventional use of a 24-h inter-trial recovery time with those of 3 h and 30 min for the determination of CP and W'. METHODS: 9 moderately trained cyclists performed an incremental test to exhaustion to establish the power output associated with the maximum oxygen uptake (p[Formula: see text]max), and 3 protocols requiring time-to-exhaustion trials at a constant work-rate performed at 80%, 100% and 105% of p[Formula: see text]max...
August 17, 2016: Journal of Sports Sciences
https://www.readbyqxmd.com/read/27519120/energy-deposition-of-single-femtosecond-filaments-in-the-atmosphere
#19
E W Rosenthal, N Jhajj, I Larkin, S Zahedpour, J K Wahlstrand, H M Milchberg
We present spatially resolved measurements of energy deposition into atmospheric air by femtosecond laser filaments. Single filaments formed with varying laser pulse energy and pulsewidth were examined using longitudinal interferometry, sonographic probing, and direct energy loss measurements. We measure peak and average energy absorption of ∼4  μJ/cm and ∼1  μJ/cm for input pulse powers up to ∼6 times the critical power for self-focusing.
August 15, 2016: Optics Letters
https://www.readbyqxmd.com/read/27491618/short-term-interval-training-at-both-lower-and-higher-intensities-in-the-severe-exercise-domain-result-in-improvements-in-formula-see-text-on-kinetics
#20
Tiago Turnes, Rafael Alves de Aguiar, Rogério Santos de Oliveira Cruz, Felipe Domingos Lisbôa, Kayo Leonardo Pereira, Fabrizio Caputo
PURPOSE: Although high-intensity interval training (HIT) seems to promote greater improvements in aerobic parameters than continuous training, the influence of exercise intensity on [Formula: see text] on-kinetics remains under investigation. METHODS: After an incremental test, twenty-one recreationally trained cyclists performed several time-to-exhaustion tests to determine critical power (CP), and the highest intensity (I HIGH), and the lowest exercise duration (T LOW) at which [Formula: see text] is attained during constant exercise...
October 2016: European Journal of Applied Physiology
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