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Critical power and fatigue

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https://www.readbyqxmd.com/read/29124324/the-effect-of-mental-fatigue-on-critical-power-during-cycling-exercise
#1
Hawbeer Salam, Samuele M Marcora, James G Hopker
PURPOSE: Time to exhaustion (TTE) tests used in the determination of critical power (CP) and curvature constant (W') of the power-duration relationship are strongly influenced by the perception of effort (PE). This study aimed to investigate whether manipulation of the PE alters the CP and W'. METHODS: Eleven trained cyclists completed a series of TTE tests to establish CP and W' under two conditions, following a mentally fatiguing (MF), or a control (CON) task...
November 9, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/29117071/deception-improves-tt-performance-in-well-trained-cyclists-without-augmented-fatigue
#2
Paul Ansdell, Kevin Thomas, Glyn Howatson, Markus Amann, Stuart Goodall
PURPOSE: To investigate the effects of feedback, in the form of a virtual avatar paced at 100 and 102% of baseline performance, on neuromuscular fatigue following a 4 km cycling time trial (TT). We hypothesised that improved cycling performance would occur due to participants exceeding a previously established critical threshold, and experiencing greater neuromuscular fatigue. METHODS: Following familiarisation, ten well-trained cyclists performed a baseline 4 km TT without feedback (BASE), followed by two, 4 km TT where they raced against an avatar (set at 100% [accurate - ACC] and 102% [deception - DEC] of baseline power output), in a randomised and counterbalanced order...
November 7, 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28991714/the-pharmacological-and-non-pharmacological-interventions-for-the-management-of-fatigue-related-multiple-sclerosis
#3
REVIEW
Philippa Miller, Andrew Soundy
AIM: The clinical aim was to provide up-to-date evidence-based recommendations for the treatment of MS-related fatigue (MSRF). The scientific aim was to prioritise topics for future randomised clinical trials with sufficient power. METHODS: A systematic search of review based research that considered MSRF in adults (18years and over) was undertaken in May 2016. Data from reviews was extracted, critically appraised and synthesised using four specific techniques. RESULTS: A total of 24 reviews were identified (17 non-pharmacological, 5 pharmacological, 2 combining both), which contained 339 studies on interventions deigned to improve MSRF...
October 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/28983275/cortical-substrate-of-supraspinal-fatigue-following-exhaustive-aerobic-exercise-localizes-to-a-large-cluster-in-the-anterior-premotor-cortex
#4
Priyantha Herath, Martin Carmichael, Angela Murphy, Leonardo Bonilha, Roger Newman-Norlund, Chris Rorden, Mark Davis
Strenuous exercise leads to a progressive reduction in the performance of voluntary physical exercise. This is due to a process described as fatigue and is defined as the failure to maintain the required or expected power output. While some of this is muscular in origin, there are data suggestive of how fatigue is modulated by cortical signals, leading to a concept of central fatigue. The previously reported fatigue-induced changes in cortical activity may have been due to blood oxygen-dependent (BOLD) signal drift and/or neural habituation alone...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28958430/limitations-of-oxygen-uptake-and-leg-muscle-activity-during-ascending-evacuation-in-stairways
#5
Amitava Halder, Kalev Kuklane, Chuansi Gao, Michael Miller, Mattias Delin, Johan Norén, Karl Fridolf
Stair ascending performance is critical during evacuation from buildings and underground infrastructures. Healthy subjects performed self-paced ascent in three settings: 13 floor building, 31 floor building, 33 m stationary subway escalator. To investigate leg muscle and cardiorespiratory capacities and how they constrain performance, oxygen uptake (VO2), heart rate (HR) and ascending speed were measured in all three; electromyography (EMG) in the first two. The VO2 and HR ranged from 89 to 96% of the maximum capacity reported in the literature...
January 2018: Applied Ergonomics
https://www.readbyqxmd.com/read/28932908/the-impact-of-specialized-palliative-care-on-cancer-patients-health-related-quality-of-life-a-systematic-review-and-meta-analysis
#6
REVIEW
Angelos P Kassianos, Myria Ioannou, Marianna Koutsantoni, Haris Charalambous
PURPOSE: Specialized palliative care (SPC) is currently underutilized or provided late in cancer care. The aim of this systematic review and meta-analysis is to critically evaluate the impact of SPC on patients' health-related quality of life (HRQoL). METHODS: Five databases were searched through June 2016. Randomized controlled trials (RCTs) and prospective studies using a pre- and post- assessment of HRQoL were included. The PRISMA reporting statement was followed...
September 20, 2017: Supportive Care in Cancer: Official Journal of the Multinational Association of Supportive Care in Cancer
https://www.readbyqxmd.com/read/28760817/non-pharmacological-interventions-for-management-of-fatigue-among-children-with-cancer-systematic-review-of-existing-practices-and-their-effectiveness
#7
Tushti Bhardwaj, Jonathan Koffman
OBJECTIVES: Fatigue is common among children living with cancer, particularly in advance stages. Little is known about the effectiveness of non-pharmacological approaches to manage this complex and distressing symptom among children. Thus, the present paper aim to critically examine the effectiveness and setting for non-pharmacological interventions to manage fatigue among children with cancer. METHODS: Six electronic databases were screened first in February 2013 and at second instance in March 2015...
July 31, 2017: BMJ Supportive & Palliative Care
https://www.readbyqxmd.com/read/28720183/g-loc-warning-algorithms-based-on-emg-features-of-the-gastrocnemius-muscle
#8
Sungho Kim, Taehwan Cho, Yongkyun Lee, Hyojin Koo, Booyong Choi, Dongsoo Kim
BACKGROUND: G-induced loss of consciousness (G-LOC) is mainly caused by failure to sustain an oxygenated blood supply to the pilot's brain because of the sudden acceleration in the direction of the +Gz axis, and is considered a critical safety issue. The purpose of this study was to develop G-LOC warning algorithms based on monitoring electromyograms (EMG) of the gastrocnemius muscle on the calf. METHODS: EMG data was retrieved from a total of 67 pilots and pilot trainees of the Korean Air Force during high-G training on a human centrifugal simulator...
August 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28700603/the-language-of-glove-wireless-gesture-decoder-with-low-power-and-stretchable-hybrid-electronics
#9
Timothy F O'Connor, Matthew E Fach, Rachel Miller, Samuel E Root, Patrick P Mercier, Darren J Lipomi
This communication describes a glove capable of wirelessly translating the American Sign Language (ASL) alphabet into text displayable on a computer or smartphone. The key components of the device are strain sensors comprising a piezoresistive composite of carbon particles embedded in a fluoroelastomer. These sensors are integrated with a wearable electronic module consisting of digitizers, a microcontroller, and a Bluetooth radio. Finite-element analysis predicts a peak strain on the sensors of 5% when the knuckles are fully bent...
2017: PloS One
https://www.readbyqxmd.com/read/28640386/photoresponsive-smart-coloration-electrochromic-supercapacitor
#10
Tae Gwang Yun, Donghyuk Kim, Yong Ho Kim, Minkyu Park, Seungmin Hyun, Seung Min Han
Electrochromic devices have been widely adopted in energy saving applications by taking advantage of the electrode coloration, but it is critical to develop a new electrochromic device that can undergo smart coloration and can have a wide spectrum in transmittance in response to input light intensity while also functioning as a rechargeable energy storage system. In this study, a photoresponsive electrochromic supercapacitor based on cellulose-nanofiber/Ag-nanowire/reduced-graphene-oxide/WO3 -composite electrode that is capable of undergoing "smart" reversible coloration while simultaneously functioning as a reliable energy-storage device is developed...
August 2017: Advanced Materials
https://www.readbyqxmd.com/read/28608135/can-proportional-ventilation-modes-facilitate-exercise-in-critically-ill-patients-a-physiological-cross-over-study-pressure-support-versus-proportional-ventilation-during-lower-limb-exercise-in-ventilated-critically-ill-patients
#11
Evangelia Akoumianaki, Nicolas Dousse, Aissam Lyazidi, Jean-Claude Lefebvre, Severine Graf, Ricardo Luiz Cordioli, Nathalie Rey, Jean-Christophe Marie Richard, Laurent Brochard
BACKGROUND: Early exercise of critically ill patients may have beneficial effects on muscle strength, mass and systemic inflammation. During pressure support ventilation (PSV), a mismatch between demand and assist could increase work of breathing and limit exercise. A better exercise tolerance is possible with a proportional mode of ventilation (Proportional Assist Ventilation, PAV+ and Neurally Adjusted Ventilatory Assist, NAVA). We examined whether, in critically ill patients, PSV and proportional ventilation have different effects on respiratory muscles unloading and work efficiency during exercise...
December 2017: Annals of Intensive Care
https://www.readbyqxmd.com/read/28596738/intensity-and-duration-based-options-to-regulate-endurance-training
#12
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/28332113/the-critical-power-concept-applications-to-sports-performance-with-a-focus-on-intermittent-high-intensity-exercise
#13
REVIEW
Andrew M Jones, Anni Vanhatalo
The curvilinear relationship between power output and the time for which it can be sustained is a fundamental and well-known feature of high-intensity exercise performance. This relationship 'levels off' at a 'critical power' (CP) that separates power outputs that can be sustained with stable values of, for example, muscle phosphocreatine, blood lactate, and pulmonary oxygen uptake ([Formula: see text]), from power outputs where these variables change continuously with time until their respective minimum and maximum values are reached and exercise intolerance occurs...
March 2017: Sports Medicine
https://www.readbyqxmd.com/read/28265030/wind-resource-assessment-in-heterogeneous-terrain
#14
C Vanderwel, M Placidi, B Ganapathisubramani
High-resolution particle image velocimetry data obtained in rough-wall boundary layer experiments are re-analysed to examine the influence of surface roughness heterogeneities on wind resource. Two different types of heterogeneities are examined: (i) surfaces with repeating roughness units of the order of the boundary layer thickness (Placidi & Ganapathisubramani. 2015 J. Fluid Mech.782, 541-566. (doi:10.1017/jfm.2015.552)) and (ii) surfaces with streamwise-aligned elevated strips that mimic adjacent hills and valleys (Vanderwel & Ganapathisubramani...
April 13, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28160103/stents-biomechanics-biomaterials-and-insights-from-computational-modeling
#15
REVIEW
Georgia S Karanasiou, Michail I Papafaklis, Claire Conway, Lampros K Michalis, Rami Tzafriri, Elazer R Edelman, Dimitrios I Fotiadis
Coronary stents have revolutionized the treatment of coronary artery disease. Improvement in clinical outcomes requires detailed evaluation of the performance of stent biomechanics and the effectiveness as well as safety of biomaterials aiming at optimization of endovascular devices. Stents need to harmonize the hemodynamic environment and promote beneficial vessel healing processes with decreased thrombogenicity. Stent design variables and expansion properties are critical for vessel scaffolding. Drug-elution from stents, can help inhibit in-stent restenosis, but adds further complexity as drug release kinetics and coating formulations can dominate tissue responses...
April 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28008101/muscle-metabolic-and-neuromuscular-determinants-of-fatigue-during-cycling-in-different-exercise-intensity-domains
#16
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 N Mileva, Joanna L Bowtell, Anni Vanhatalo
Lactate or gas exchange threshold (GET) and 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 men 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...
March 1, 2017: 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
#17
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/27806677/power-duration-relationship-physiology-fatigue-and-the-limits-of-human-performance
#18
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/27802700/response-measurement-by-laser-doppler-vibrometry-in-vibration-qualification-tests-with-non-gaussian-random-excitation
#19
M Troncossi, R Di Sante, A Rivola
In the field of vibration qualification testing, random excitations are typically imposed on the tested system in terms of a power spectral density (PSD) profile. This is the one of the most popular ways to control the shaker or slip table for durability tests. However, these excitations (and the corresponding system responses) exhibit a Gaussian probability distribution, whereas not all real-life excitations are Gaussian, causing the response to be also non-Gaussian. In order to introduce non-Gaussian peaks, a further parameter, i...
October 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27788474/compression-fatigue-behavior-and-failure-mechanism-of-porous-titanium-for-biomedical-applications
#20
Fuping Li, Jinshan Li, Tingting Huang, Hongchao Kou, Lian Zhou
Porous titanium and its alloys are believed to be one of the most attractive biomaterials for orthopedic implant applications. In the present work, porous pure titanium with 50-70% porosity and different pore size was fabricated by diffusion bonding. Compression fatigue behavior was systematically studied along the out-of-plane direction. It resulted that porous pure titanium has anisotropic pore structure and the microstructure is fine-grained equiaxed α phase with a few twins in some α grains. Porosity and pore size have some effect on the S-N curve but this effect is negligible when the fatigue strength is normalized by the yield stress...
January 2017: Journal of the Mechanical Behavior of Biomedical Materials
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