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https://www.readbyqxmd.com/read/28892462/cycling-performance-is-superior-for-time-to-exhaustion-versus-time-trial-in-endurance-laboratory-tests
#1
Sarah L Coakley, Louis Passfield
Time-to-exhaustion (TTE) trials are used in a laboratory setting to measure endurance performance. However, there is some concern with their ecological validity compared with time-trials (TT). Consequently, we aimed to compare cycling performance in TTE and TT where the duration of the trials was matched. Seventeen trained male cyclists completed three TTE trials at 80, 100 and 105% of maximal aerobic power (MAP). On a subsequent visit they performed three TT over the same duration as the TTE. Participants were blinded to elapsed time, power output, cadence and heart rate (HR)...
September 11, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28866575/treepod-sensitivity-aware-selection-of-pareto-optimal-decision-trees
#2
Thomas Muhlbacher, Lorenz Linhardt, Torsten Moller, Harald Piringer
Balancing accuracy gains with other objectives such as interpretability is a key challenge when building decision trees. However, this process is difficult to automate because it involves know-how about the domain as well as the purpose of the model. This paper presents TreePOD, a new approach for sensitivity-aware model selection along trade-offs. TreePOD is based on exploring a large set of candidate trees generated by sampling the parameters of tree construction algorithms. Based on this set, visualizations of quantitative and qualitative tree aspects provide a comprehensive overview of possible tree characteristics...
August 29, 2017: IEEE Transactions on Visualization and Computer Graphics
https://www.readbyqxmd.com/read/28860660/free-space-nonlinear-beam-combining-for-high-intensity-projection
#3
Shermineh Rostami Fairchild, Wiktor Walasik, Daniel Kepler, Matthieu Baudelet, Natalia M Litchinitser, Martin Richardson
The controlled interaction of two high intensity beams opens new degrees of freedom for manipulating electromagnetic waves in air. The growing number of applications for laser filaments requires fine control of their formation and propagation. We demonstrate, experimentally and theoretically, that the attraction and fusion of two parallel ultrashort beams with initial powers below the critical value (70% P critical), in the regime where the non-linear optical characteristics of the medium become dominant, enable the eventual formation of a filament downstream...
August 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28832393/caffeine-increases-work-done-above-critical-power-but-not-anaerobic-work
#4
Rodrigo Silveira, Victor Amorim Andrade-Souza, Lucyana Arcoverde, Fabiano Tomazini, André Sansonio, David John Bishop, Romulo Bertuzzi, Adriano Eduardo Lima-Silva
PURPOSE: The assumption that the curvature constant (W´) of the power-duration relationship represents anaerobic work capacity is a controversial, unresolved question. We investigated if caffeine ingestion could increase total work done above critical power (CP), and if this would be accompanied by greater anaerobic energy expenditure and by an enhanced maintenance of maximal oxidative metabolic rate. METHODS: Nine men (26.6 ± 5.3 years, V˙O2max 40.6 ± 5.8 mL·kg·min) cycled until exhaustion at different exercise intensities on different days to determine the CP and W´...
August 21, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28795742/optical-reconfiguration-and-polarization-control-in-semi-continuous-gold-films-close-to-the-percolation-threshold
#5
Christian Frydendahl, Taavi Repän, Mathias Geisler, Sergey M Novikov, Jonas Beermann, Andrei V Lavrinenko, Sanshui Xiao, Sergey I Bozhevolnyi, N Asger Mortensen, Nicolas Stenger
Controlling and confining light by exciting plasmons in resonant metallic nanostructures is an essential aspect of many new emerging optical technologies. Here we explore the possibility of controllably reconfiguring the intrinsic optical properties of semi-continuous gold films, by inducing permanent morphological changes with a femtosecond (fs)-pulsed laser above a critical power. Optical transmission spectroscopy measurements show a correlation between the spectra of the morphologically modified films and the wavelength, polarization, and the intensity of the laser used for alteration...
August 24, 2017: Nanoscale
https://www.readbyqxmd.com/read/28742832/the-relationship-between-movement-speed-and-duration-during-soccer-matches
#6
Kai Roecker, Hubert Mahler, Christian Heyde, Mareike Röll, Albert Gollhofer
The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0...
2017: PloS One
https://www.readbyqxmd.com/read/28704307/acute-cardiopulmonary-metabolic-and-neuromuscular-responses-to-severe-intensity-intermittent-exercises
#7
Felipe D Lisbôa, João A G Raimundo, Amadeo F Salvador, Kayo L Pereira, Tiago Turnes, Fernando Diefenthaeler, Mariana F M de Oliveira, Fabrizio Caputo
The purpose of this study was to compare cardiopulmonary, neuromuscular, and metabolic responses to severe-intensity intermittent exercises with variable or constant work rate. Eleven cyclists (28 ± 5 years; 74 ± 7 kg; 175 ± 5 cm; 63 ± 4 mL·kg·min) performed the following tests until exhaustion on separate days: 1) an incremental test; 2) in random order, two constant work rate tests at 95% and 110% of the peak power for the determination of Critical Power (CP); 3) 2-4 tests for the determination of the highest power that still permits the achievement of maximal oxygen uptake (PHIGH); and 4) two random severe-intensity intermittent exercises...
July 12, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28687955/effects-of-recovery-interval-duration-on-the-parameters-of-the-critical-power-model-for-incremental-exercise
#8
Giovanni Vinetti, Nazzareno Fagoni, Anna Taboni, Stefano Camelio, Pietro Enrico di Prampero, Guido Ferretti
INTRODUCTION: We tested the linear critical power ([Formula: see text]) model for discrete incremental ramp exercise implying recovery intervals at the end of each step. METHODS: Seven subjects performed incremental (power increment 25 W) stepwise ramps to subject's exhaustion, with recovery intervals at the end of each step. Ramps' slopes (S) were 0.83, 0.42, 0.28, 0.21, and 0.08 W s(-1); recovery durations (t r) were 0 (continuous stepwise ramps), 60, and 180 s (discontinuous stepwise ramps)...
July 7, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28686083/ischemic-preconditioning-enhances-critical-power-during-a-3-minute-all-out-cycling-test
#9
Patrick J Griffin, Richard A Ferguson, Conor Gissane, Stephen J Bailey, Stephen D Patterson
This study tested the hypothesis that ischemic preconditioning (IPC) would increase critical power (CP) during a 3 minute all-out cycling test. Twelve males completed two 3 minute all-out cycling tests, in a crossover design, separated by 7 days. These tests were preceded by IPC (4 x 5 minute intervals at 220 mmHg bilateral leg occlusion) or SHAM treatment (4 x 5 minute intervals at 20 mmHg bilateral leg occlusion). CP was calculated as the mean power output during the final 30 s of the 3 minute test with W' taken as the total work done above CP...
July 7, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28627041/prior-exercise-speeds-pulmonary-oxygen-uptake-kinetics-and-increases-critical-power-during-supine-but-not-upright-cycling
#10
Richie P Goulding, Denise M Roche, Simon Marwood
What is the central question of this study? Critical power (CP) represents the highest work rate for which a metabolic steady state is attainable. The physiological determinants of CP are unclear, but research suggests that CP might be related to the time constant of phase II oxygen uptake kinetics (τV̇O2). What is the main finding and its importance? We provide the first evidence that τV̇O2 is mechanistically related to CP. A reduction of τV̇O2 in the supine position was observed alongside a concomitant increase in CP...
June 19, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28617848/effect-of-caffeine-ingestion-on-anaerobic-capacity-quantified-by-different-methods
#11
RANDOMIZED CONTROLLED TRIAL
Lucyana Arcoverde, Rodrigo Silveira, Fabiano Tomazini, André Sansonio, Romulo Bertuzzi, Adriano Eduardo Lima-Silva, Victor Amorim Andrade-Souza
We investigated whether caffeine ingestion before submaximal exercise bouts would affect supramaximal oxygen demand and maximal accumulated oxygen deficit (MAOD), and if caffeine-induced improvement on the anaerobic capacity (AC) could be detected by different methods. Nine men took part in several submaximal and supramaximal exercise bouts one hour after ingesting caffeine (5 mg·kg-1) or placebo. The AC was estimated by MAOD, alternative MAOD, critical power, and gross efficiency methods. Caffeine had no effect on exercise endurance during the supramaximal bout (caffeine: 131...
2017: PloS One
https://www.readbyqxmd.com/read/28607465/spiraling-elliptic-hermite-gaussian-solitons-in-nonlocal-nonlinear-media-without-anisotropy
#12
Guo Liang, Zhiping Dai
We introduce a kind of the spiraling elliptic Hermite-Gaussian solitons in nonlocal nonlinear media without anisotropy, which carries the orbital angular momentum and can rotate in the transverse. The n-th mode of the spiraling elliptic Hermite-Gaussian solitons has n holes nested in the elliptic profile. The analytical spiraling elliptic Hermite-Gaussian solitons solutions are obtained based on the variational approach, which agree well with the numerical simulations. It is found that the critical power and the critical angular velocity for the spiraling elliptic Hermite-Gaussian solitons are the same as the counterpart of the ground mode...
June 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28596738/intensity-and-duration-based-options-to-regulate-endurance-training
#13
Peter Hofmann, Gerhard Tschakert
The regulation of endurance training is usually based on the prescription of exercise intensity. Exercise duration, another important variable of training load, is rarely prescribed by individual measures and mostly set from experience. As the specific exercise duration for any intensity plays a substantial role regarding the different kind of cellular stressors, degree, and kind of fatigue as well as training effects, concepts integrating the prescription of both intensity and duration within one model are needed...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28530517/contributions-of-body-composition-characteristics-to-critical-power-and-anaerobic-work-capacity
#14
M Travis Byrd, Jonathan Robert Switalla, Joel E Eastman, Brian J Wallace, Jody L Clasey, Haley C Bergstrom
Critical power (CP) and anaerobic work capacity (AWC) from the CP test represent distinct parameters related to metabolic characteristics of the whole body and active muscle tissue, respectively. PURPOSE: This study examined the contribution of whole body composition characteristics and local lean mass to further elucidate the differences in metabolic characteristics between CP and AWC as they relate to whole body and local factors. METHODS: Fifteen, anaerobically trained males were assessed for whole body (% body fat [%BF] and mineral-free, lean mass [LBM]) and local mineral-free thigh lean mass (TLM) composition characteristic...
May 22, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28530476/time-trials-versus-time-to-exhaustion-tests-effects-on-critical-power-w-and-oxygen-uptake-kinetics
#15
Bettina Karsten, Jonathan Baker, Fernando Naclerio, Andreas Klose, Antonino Bianco, Alfred Nimmerichter
PURPOSE: To investigate single-day time-to-exhaustion (TTE) and time trial (TT) based laboratory tests values of critical power (CP), Wprime (W') and respective oxygen kinetics responses. METHODS: Twelve cyclists performed a maximal ramp test followed by three TTE and three TT efforts interspersed by a 60-min recovery between efforts. Oxygen uptake was measured during all trials. The mean response time (MRT) was calculated as a description of the overall V̇O2 kinetic response from the onset to 2 min of exercise...
May 22, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28479931/cardiorespiratory-fitness-and-aerobic-performance-adaptations-to-a-4-week-sprint-interval-training-in-young-healthy-untrained-females
#16
Mykolas Kavaliauskas, Thomas P Steer, John A Babraj
PURPOSE: The aim of this study was to test the effects of sprint interval training (SIT) on cardiorespiratory fitness and aerobic performance measures in young females. METHODS: Eight healthy, untrained females (age 21 ± 1 years; height 165 ± 5 cm; body mass 63 ± 6 kg) completed cycling peak oxygen uptake ([Formula: see text] peak), 10-km cycling time trial (TT) and critical power (CP) tests pre- and post-SIT. SIT protocol included 4 × 30-s "all-out" cycling efforts against 7 % body mass interspersed with 4 min of active recovery performed twice per week for 4 weeks (eight sessions in total)...
2017: Sport Sciences for Health
https://www.readbyqxmd.com/read/28437928/terahertz-optical-bistability-of-graphene-in-thin-layers-of-dielectrics
#17
Kwang Jun Ahn, Fabian Rotermund
We theoretically studied in terahertz frequency regime optical bistability of graphene placed at the interface between thin dielectric layers. We solved self-consistently the nonlinear wave equations containing the third-order optical conductivity of graphene in four-layer structures and obtained hysteresis response of the transmitted power as a function of the incident power. We numerically observed that the critical powers for the up and down transitions and the Fermi-energy of graphene required for terahertz optical bistability can be reduced by carefully choosing material properties and the thicknesses of dielectric layers...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28388783/the-reliability-and-validity-of-the-3-min-all-out-cycling-critical-power-test
#18
James Wright, Stewart Bruce-Low, Simon A Jobson
Research suggests that critical power (CP) can be estimated from a single 3-min bout of all-out cycling. The purpose of this study was to investigate the reliability and validity of the 3-min all-out cycling test when carried out at a constant cadence (isokinetic) and against a fixed resistance (linear). 12 participants completed 8 tests: 1) a ramp test; 2-4) 3 fixed power tests to calculate CP and W' using the 1/time mathematical model; 5-8) four 3-min all-out tests to calculate EP and WEP; 2 isokinetic and 2 linear tests...
June 2017: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/28386237/prediction-of-critical-power-and-w-in-hypoxia-application-to-work-balance-modelling
#19
Nathan E Townsend, David S Nichols, Philip F Skiba, Sebastien Racinais, Julien D Périard
Purpose: Develop a prediction equation for critical power (CP) and work above CP (W') in hypoxia for use in the work-balance ([Formula: see text]) model. Methods: Nine trained male cyclists completed cycling time trials (TT; 12, 7, and 3 min) to determine CP and W' at five altitudes (250, 1,250, 2,250, 3,250, and 4,250 m). Least squares regression was used to predict CP and W' at altitude. A high-intensity intermittent test (HIIT) was performed at 250 and 2,250 m. Actual and predicted CP and W' were used to compute W' during HIIT using differential ([Formula: see text]) and integral ([Formula: see text]) forms of the [Formula: see text] model...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28367980/power-scalable-subcycle-pulses-from-laser-filaments
#20
A A Voronin, A M Zheltikov
Compression of optical pulses to ultrashort pulse widths using methods of nonlinear optics is a well-established technology of modern laser science. Extending these methods to pulses with high peak powers, which become available due to the rapid progress of laser technologies, is, however, limited by the universal physical principles. With the ratio P/Pcr of the peak power of an ultrashort laser pulse, P, to the critical power of self-focusing, Pcr, playing the role of the fundamental number-of-particles integral of motion of the nonlinear Schrödinger equation, keeping this ratio constant is a key principle for the power scaling of laser-induced filamentation...
April 3, 2017: Scientific Reports
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