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"Critical power"

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
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
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
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...
October 27, 2016: European Journal of Applied Physiology
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
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
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
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...
September 9, 2016: European Journal of Applied Physiology
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
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
Haley Bergstrom, Terry Housh
No abstract text is available yet for this article.
May 2016: Journal of Strength and Conditioning Research
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...
August 23, 2016: International Journal of Sports Medicine
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
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
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
Andreas Pfenning, Fabian Hartmann, Fabian Langer, Martin Kamp, Sven Höfling, Lukas Worschech
We have studied the sensitivity of AlGaAs/GaAs double barrier resonant tunneling diode photodetectors with an integrated GaInNAs absorption layer for light sensing at the telecommunication wavelength of λ = 1.3 μm for illumination powers from pico- to microwatts. The sensitivity decreases nonlinearly with power. An illumination power increase of seven orders of magnitude leads to a reduction of the photocurrent sensitivity from S I  = 5.82 × 10(3) A W(-1) to 3.2 A W(-1). We attribute the nonlinear sensitivity-power dependence to an altered local electrostatic potential due to hole-accumulation that on the one hand tunes the tunneling current, but on the other hand affects the lifetime of photogenerated holes...
September 2, 2016: Nanotechnology
M C T Gama, F A B Sousa, I G M Dos Reis, C A Gobatto
The 3-min all-out test was developed and validated on a cycle ergometer using a modification of a linear mathematical equation (1/time vs. power) obtained from the original critical power model. The purpose of this development was to obtain, in a single test, the aerobic and anaerobic capacity parameters and identify the exercise transition moment from heavy to severe intensity. The aim of this study was to propose an adaptation of the all-out 3-min cycle ergometer to a non-motorized treadmill with tethered running...
July 13, 2016: International Journal of Sports Medicine
Hanling Deng, Xiaoling Ji, Xiaoqing Li, Hao Zhang, Xianqu Wang, Yuqiu Zhang
The effect of spatial coherence on laser beam self-focusing in the atmosphere to assist delivering powerful laser beams from orbit to the ground is studied. It is found that a fully coherent beam is more strongly compressed on the ground than a partially (spatial) coherent beam (PCB), even so, for a PCB the compressed spot size on the ground may be reduced below the diffraction limit due to self-focusing effect, and a PCB has higher threshold critical power than a fully coherent beam. Furthermore, an effective design rule for maximal compression without beam splitting of the transported PCB from orbit to the ground is presented...
June 27, 2016: Optics Express
Michael A Johnson, Ashley W Graham, Luke Al Ingram, Simon B Cooper, Neil C Williams, Graham R Sharpe
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Kaitlin M McLay, Felipe Mattioni Maturana, Juan M Murias
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
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