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"Critical speed"

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https://www.readbyqxmd.com/read/29651887/validity-and-reliability-of-the-3-minute-all-out-test-in-national-and-international-competitive-swimmers
#1
Eva Piatrikova, Ana C Sousa, Javier T Gonzalez, Sean Williams
PURPOSE: To assess the concurrent and predictive validity of the 3-min all-out test (3MT) against conventional methods (CM) of determining critical speed (CS) and curvature constant (D'), and to examine the test-retest reliability of the 3MT in highly-trained swimmers. METHODS: Thirteen highly-trained swimmers (age: 16 ± 2 y, weight: 64.7 ± 8.5 kg, height: 1.76 ± 0.07 m) completed four time trials, and two 3MT over 2 weeks. The distance-time (DT) and speed-1/time (1/T) models were used to determine CS and D' from four time trials...
April 13, 2018: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/29435760/prescribing-6-weeks-of-running-training-using-parameters-from-a-self-paced-maximal-oxygen-uptake-protocol
#2
James S Hogg, James G Hopker, Sarah L Coakley, Alexis R Mauger
PURPOSE: The self-paced maximal oxygen uptake test (SPV) may offer effective training prescription metrics for athletes. This study aimed to examine whether SPV-derived data could be used for training prescription. METHODS: Twenty-four recreationally active male and female runners were randomly assigned between two training groups: (1) Standardised (STND) and (2) Self-Paced (S-P). Participants completed 4 running sessions a week using a global positioning system-enabled (GPS) watch: 2 × interval sessions; 1 × recovery run; and 1 × tempo run...
February 12, 2018: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/29432324/classification-of-intensity-in-team-sport-activity
#3
Ted Polglaze, Cruz Hogan, Brian Dawson, Alec Buttfield, Cristian Osgnach, Leanne Lester, Peter Peeling
PURPOSE: To assess the efficacy of critical metabolic power derived from variable-speed movement for classifying intensity in team sport activity. METHODS: Elite male hockey players (n = 12) completed a series of time trials (100 yd, 400 yd, 1500 yd) and a 3-min all-out test to derive both critical speed (CS) and critical power (CP). Heart rate (HR), blood lactate (BLa) and rating of perceived exertion (RPE) were measured during each protocol. Participants (n = 10) then played 2 competitive hockey matches...
February 9, 2018: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/29334328/different-durations-within-the-method-of-best-practice-affect-the-parameters-of-the-speed-duration-relationship
#4
Christoph Triska, Bettina Karsten, Chris Beedie, Bernhard Koller-Zeisler, Alfred Nimmerichter, Harald Tschan
The aim of the study was to determine whether estimates of the speed-duration relationship are affected using different time-trial (TT) field-based testing protocols, where exhaustive times were located within the generally recommended durations of 2-15 min. Ten triathletes (mean ± SD age: 31.0 ± 5.7 years; height: 1.81 ± 0.05 m; body mass: 76.5 ± 6.8 kg) performed two randomly assigned field tests to determine critical speed (CS) and the total distance covered above CS (D́). CS and D́ were obtained using two different protocols comprising three TT that were interspersed by 60 min passive rest...
April 2018: European Journal of Sport Science
https://www.readbyqxmd.com/read/29251174/reliability-and-validity-of-a-modified-3-minute-all-out-swimming-test-in-elite-swimmers
#5
Lachlan J G Mitchell, David B Pyne, Philo U Saunders, Ben Rattray
Critical speed (CS) testing is useful in monitoring training in swimmers, however, completing a series of time trials (TTs) regularly is time-consuming. The 3-minute test may be a solution with positive initial findings. This investigation examined whether a modified 3-minute test (12 × 25 m) could assess CS and supra-CS distance capacity (D') in swimmers. A series of 12 × 25 m intervals were completed unpaced at maximal effort, interspersed with 5 s rest periods. The model speed = a eb t  + c was fitted to the data and integrated to calculate D'...
April 2018: European Journal of Sport Science
https://www.readbyqxmd.com/read/29242309/physiological-differences-between-a-noncontinuous-and-a-continuous-endurance-training-protocol-in-recreational-runners-and-metabolic-demand-prediction
#6
Muhammad J Ali, Balasekaran Govindasamay, Hoon Kay Hiang, Gerald Seet Gim Lee
This study investigated the physiological difference in recreational runners between a noncontinuous and a continuous endurance training protocol. It also aimed to determine physiological surrogate that could monitor metabolic demand of prolonged running in real-time. For data collection, a total of 18 active male recreational runners were recruited. Physiological (HR, RR, RER, Ṽ O2 , BLa), and overall perceptual (RPEO ) responses were recorded against three designed test sessions. Session 1 included Ṽ O2submax test to determine critical speed (CS) at anaerobic threshold (AT)...
December 2017: Physiological Reports
https://www.readbyqxmd.com/read/29229821/critical-dynamics-in-population-vaccinating-behavior
#7
A Demetri Pananos, Thomas M Bury, Clara Wang, Justin Schonfeld, Sharada P Mohanty, Brendan Nyhan, Marcel Salathé, Chris T Bauch
Vaccine refusal can lead to renewed outbreaks of previously eliminated diseases and even delay global eradication. Vaccinating decisions exemplify a complex, coupled system where vaccinating behavior and disease dynamics influence one another. Such systems often exhibit critical phenomena-special dynamics close to a tipping point leading to a new dynamical regime. For instance, critical slowing down (declining rate of recovery from small perturbations) may emerge as a tipping point is approached. Here, we collected and geocoded tweets about measles-mumps-rubella vaccine and classified their sentiment using machine-learning algorithms...
December 26, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28878562/flexural-edge-waves-generated-by-steady-state-propagation-of-a-loaded-rectilinear-crack-in-an-elastically-supported-thin-plate
#8
Andrea Nobili, Enrico Radi, Luca Lanzoni
The problem of a rectilinear crack propagating at constant speed in an elastically supported thin plate and acted upon by an equally moving load is considered. The full-field solution is obtained and the spotlight is set on flexural edge wave generation. Below the critical speed for the appearance of travelling waves, a threshold speed is met which marks the transformation of decaying edge waves into edge waves propagating along the crack and dying away from it. Yet, besides these, and for any propagation speed, a pair of localized edge waves, which rapidly decay behind the crack tip, is also shown to exist...
August 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28773243/impact-load-behavior-between-different-charge-and-lifter-in-a-laboratory-scale-mill
#9
Zixin Yin, Yuxing Peng, Zhencai Zhu, Zhangfa Yu, Tongqing Li
The impact behavior between the charge and lifter has significant effect to address the mill processing, and is affected by various factors including mill speed, mill filling, lifter height and media shape. To investigate the multi-body impact load behavior, a series of experiments and Discrete Element Method (DEM) simulations were performed on a laboratory-scale mill, in order to improve the grinding efficiency and prolong the life of the lifter. DEM simulation hitherto has been extensively applied as a leading tool to describe diverse issues in granular processes...
July 31, 2017: Materials
https://www.readbyqxmd.com/read/28723814/validation-of-the-3-min-all-out-exercise-test-for-shuttle-running-prescription
#10
Anssi Saari, Nathan D Dicks, Mark E Hartman, Robert W Pettitt
A 3-min all-out exercise test (3MT) for running has been developed to determine critical speed (CS) and finite capacity for running speeds >CS (D') which allow for the prediction of time limits (TLIMs) associated with running different distances. Most team sports require shuttle running; however, the 3MT was validated for uninterrupted, track running and not shuttle running. The purpose of this study was to examine the efficacy of shuttle running 3MT to determine critical speed (CS) and D'. A total of 12 subjects were tested using a baseline 3MT along with three separate distance time-trials of all-out shuttle running to determine true CS and D'...
July 17, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28542091/normative-data-for-critical-speed-and-d-for-high-level-male-rugby-players
#11
Mark Kramer, Ida E Clark, Nick Jamnick, Cody Strom, Robert W Pettitt
The critical speed (CS) concept helps characterize the aerobic and anaerobic fitness of an athlete. Rugby players should hypothetically have modest CS values but extremely high curvature constant (D') values, yet, normative data are currently unavailable. To develop normative data of CS and D' for high-level male rugby players, a total of 30 male rugby players, were recruited from the Eastern Cape of South Africa. All subjects performed the running 3-min all-out exercise test (3 MT) using global positioning system (GPS) technology to determine CS and D'...
March 8, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28514809/iso-duration-determination-of-d%C3%A2-and-cs-under-laboratory-and-field-conditions
#12
Christoph Triska, Bettina Karsten, Alfred Nimmerichter, Harald Tschan
Whilst Critical Speed (CS) has been successfully translated from the laboratory into the field, this translation is still outstanding for the related maximum running distance (D'). Using iso-duration exhaustive laboratory and field runs, this study investigated the potential interchangeable use of both parameters, D' and CS. After an incremental exercise test, 10 male participants (age: 24.9±2.1 yrs; height: 180.8±5.8 cm; body mass: 75.3±8.6 kg; V̇ ˙VO2peak 52.9±3.1 mL∙min(-1)∙kg(-1)) performed 3 time-to-exhaustion runs on a treadmill followed by 3 exhaustive time-trial runs on a-400 m athletics outdoor track...
July 2017: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/28034367/dendritic-trafficking-faces-physiologically-critical-speed-precision-tradeoffs
#13
Alex H Williams, Cian O'Donnell, Terrence J Sejnowski, Timothy O'Leary
Nervous system function requires intracellular transport of channels, receptors, mRNAs, and other cargo throughout complex neuronal morphologies. Local signals such as synaptic input can regulate cargo trafficking, motivating the leading conceptual model of neuron-wide transport, sometimes called the 'sushi-belt model' (Doyle and Kiebler, 2011). Current theories and experiments are based on this model, yet its predictions are not rigorously understood. We formalized the sushi belt model mathematically, and show that it can achieve arbitrarily complex spatial distributions of cargo in reconstructed morphologies...
December 30, 2016: ELife
https://www.readbyqxmd.com/read/28007073/closing-in-on-the-pumpkin-trial-of-the-jarvik-2015-ventricular-assist-device
#14
REVIEW
J Timothy Baldwin, Iki Adachi, John Teal, Christopher A Almond, Robert D Jaquiss, M Patricia Massicotte, Kurt Dasse, Flora S Siami, Victor Zak, Jonathan R Kaltman, William T Mahle, Robert Jarvik
The Infant Jarvik ventricular assist device (VAD; Jarvik Heart, Inc., New York, NY) has been developed to support the circulation of infants and children with advanced heart failure. The first version of the device was determined to have elevated hemolysis under certain conditions. The objective of this work was to determine appropriate modifications to the Infant Jarvik VAD that would result in acceptably low hemolysis levels. In vitro hemolysis testing revealed that hemolysis was related to the shape of the pump blade tips and a critical speed over which hemolysis would occur...
January 2017: Seminars in Thoracic and Cardiovascular Surgery. Pediatric Cardiac Surgery Annual
https://www.readbyqxmd.com/read/27925233/quantification-and-analysis-of-leaflet-flutter-on-biological-prosthetic-cardiac-valves
#15
Artur H de F Avelar, Jean A Canestri, Camila Bim, Maíra G M Silva, Rudolf Huebner, Marcos Pinotti
The use of porcine or bovine pericardium biological cardiac valves has as its main disadvantage a relatively short lifespan, with failures due to calcification and fatigue. Increasing these valves' durability constitutes a great challenge. An understudied phenomenon is the effect of flutter, an oscillation of the leaflets that can cause regurgitation and accelerate calcification and fatigue. As a starting point to study how to reduce or prevent these oscillations, a method was developed to quantify the flutter frequencies occurring at the point of the valve's full opening...
December 7, 2016: Artificial Organs
https://www.readbyqxmd.com/read/27463968/instantaneous-flow-structures-and-opportunities-for-larval-settlement-barnacle-larvae-swim-to-settle
#16
Ann I Larsson, Lena M Granhag, Per R Jonsson
Water flow affects settlement of marine larvae on several scales. At the smallest scale local flow regime may control the probability of adhesion to the substrate. Our aim was to mechanistically understand the transition from suspended to attached larvae in turbulent flow. Recently it was proposed that opportunities for larval settlement in turbulent boundary layers depend on time windows with suitable instantaneous flow properties. In flume flow we characterized the proportion of suitable time windows in a series of flow velocities with focus on the near-bed flow...
2016: PloS One
https://www.readbyqxmd.com/read/27442329/modeling-of-running-performances-in-humans-comparison-of-power-laws-and-critical-speed
#17
Badrane Zinoubi, Henry Vandewalle, Tarak Driss
Zinoubi, B, Vandewalle, H, and Driss, T. Modeling of running performances in humans: comparison of power laws and critical speed. J Strength Cond Res 31(7): 1859-1867, 2017-The concepts of power law and critical speed (SCrit) have been applied to the analysis of individual running performances. We have analyzed the results of 2 exceptional runners (Nurmi and Gebrselassie) and 11 physical education students (PESs) who performed 3 exhausting running exercises. Power laws can accurately describe the relationships between exhaustion time (tlim) and distance (Dlim) or speed (S) (Equation is included in full-text article...
July 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27431779/severe-hypoxemia-induced-by-prolonged-expiration-and-reduced-frequency-breathing-during-submaximal-swimming
#18
Argyris G Toubekis, Nikolaos Beidaris, Petros G Botonis, Maria Koskolou
The purpose of this study was to examine the metabolic responses during submaximal swimming with self-selected normal breathing (N) and prolonged expiration along with reduced frequency breathing (RB). Ten male swimmers (age: 23.1 ± 2.2 years; VO2max: 47.3 ± 7.2 ml · kg(-1) · min(-1)) performed 75-, 100-, 175-, 200-, 275-, 300-, 375- and 400-m trials with N and RB at intensity corresponding to 90% of the critical speed. In RB condition, all trials longer than 75 m were interspersed with 25 m of self-selected N in regular intervals...
June 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/27379951/validity-of-treadmill-derived-critical-speed-on-predicting-5000-meter-track-running-performance
#19
RANDOMIZED CONTROLLED TRIAL
Alfred Nimmerichter, Nina Novak, Christoph Triska, Bernhard Prinz, Brynmor C Breese
Nimmerichter, A, Novak, N, Triska, C, Prinz, B, and Breese, BC. Validity of treadmill-derived critical speed on predicting 5,000-meter track-running performance. J Strength Cond Res 31(3): 706-714, 2017-To evaluate 3 models of critical speed (CS) for the prediction of 5,000-m running performance, 16 trained athletes completed an incremental test on a treadmill to determine maximal aerobic speed (MAS) and 3 randomly ordered runs to exhaustion at the [INCREMENT]70% intensity, at 110% and 98% of MAS. Critical speed and the distance covered above CS (D') were calculated using the hyperbolic speed-time (HYP), the linear distance-time (LIN), and the linear speed inverse-time model (INV)...
March 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27321993/physical-characterization-of-unfilled-and-nanofilled-dental-resins-static-versus-dynamic-mechanical-properties
#20
Parisa Saen, Mohammad Atai, Azizollah Nodehi, Laleh Solhi
OBJECTIVE: The aim of this study was to evaluate the mechanical properties of dental resins and dental nanocomposites by means of 3-point bending, 4-point bending and piston-on-three ball biaxial static tests and also to investigate their dynamic mechanical properties. The obtained results from the static 3-point bending test also were compared with the corresponding mode in DMTA. METHODS: The hydrophilic surface of the inorganic OX-50 particles was treated with γ-MPS and the resulting silanized OX-50 was characterized using FTIR and TGA...
August 2016: Dental Materials: Official Publication of the Academy of Dental Materials
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