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Power duration relationship

Ida E Clark, Anni Vanhatalo, Stephen J Bailey, Lee J Wylie, Brett S Kirby, Brad W Wilkins, Andrew M Jones
INTRODUCTION: Changes in the parameters of the power-time relationship (critical power (CP) and W') during endurance exercise would have important implications for performance. We tested the hypotheses that CP and W', estimated using the end-test power (EP) and the work done above EP (WEP), respectively, during a the 3-min all-out test (3MT), can be reliably determined, and would be lower, after completing 2-h of heavy-intensity exercise. METHODS: In study 1, six cyclists completed a 3MT immediately following 2-h of heavy-intensity exercise on two occasions to establish the reliability of EP and WEP...
March 8, 2018: Medicine and Science in Sports and Exercise
Alessandro Pozzebon, Irene Cappelli, Alessandro Mecocci, Duccio Bertoni, Giovanni Sarti, Fernanda Alquini
Direct measurements of aeolian sand transport on coastal dunes and beaches is of paramount importance to make correct decisions about coast management. As most of the existing studies are mainly based on a statistical approach, the solution presented in this paper proposes a sensing structure able to orient itself according to wind direction and directly calculate the amount of wind-transported sand by collecting it and by measuring its weight. Measurements are performed remotely without requiring human action because the structure is equipped with a ZigBee radio module, which periodically sends readings to a local gateway...
March 8, 2018: Sensors
Matthew I Black, Andrew M Jones, Paul T Morgan, Stephen J Bailey, Jonathan Fulford, Anni Vanhatalo
Purpose: To investigate the influence of β-alanine (BA) supplementation on muscle carnosine content, muscle pH and the power-duration relationship (i.e., critical power and W'). Methods: In a double-blind, randomized, placebo-controlled study, 20 recreationally-active males (22 ± 3 y, V°O2peak 3.73 ± 0.44 L·min-1 ) ingested either BA (6.4 g/d for 28 d) or placebo (PL) (6.4 g/d) for 28 d. Subjects completed an incremental test and two 3-min all-out tests separated by 1-min on a cycle ergometer pre- and post-supplementation...
2018: Frontiers in Physiology
Berthold Pemp, Stefan Palkovits, Kinga Howorka, Jiri Pumprla, Stefan Sacu, Gerhard Garhöfer, Michaela Bayerle-Eder, Leopold Schmetterer, Ursula Schmidt-Erfurth
PURPOSE: To evaluate the relationship of neuroretinal layer thickness with sensitive measures of cardiovascular autonomic neuropathy in diabetic patients with non-proliferative diabetic retinopathy (NPDR). METHODS: Twenty-seven eyes of 27 patients with type 1 diabetes presenting with mild-to-moderate NPDR were compared to 27 healthy control (HC) eyes matched for age and gender. The total macular volume (TMV) and the volumes of individual neurosensory layers in the macula were analysed from spectral domain optical coherence tomography using automated layer segmentation...
March 5, 2018: Acta Ophthalmologica
Lei Wu, Jun Jiang, Gou-Xia Li, Xiao-Yi Ma
The pulsed events of rainstorm erosion on the Loess Plateau are well-known, but little information is available concerning the characteristics of superficial soil erosion processes caused by heavy rainstorms at the watershed scale. This study statistically evaluated characteristics of pulsed runoff-erosion events based on 17 observed rainstorms from 1997-2010 in a small loess watershed on the Loess Plateau of China. Results show that: 1) Rainfall is the fundamental driving force of soil erosion on hillslopes, but the correlations of rainfall-runoff and rainfall-sediment in different rainstorms are often scattered due to infiltration-excess runoff and soil conservation measures...
February 27, 2018: Scientific Reports
Mark Mikkelsen, Rachelle S Loo, Nicolaas A J Puts, Richard A E Edden, Ashley D Harris
BACKGROUND: The relationships between scan duration, signal-to-noise ratio (SNR) and sample size must be considered and understood to design optimal GABA-edited magnetic resonance spectroscopy (MRS) studies. NEW METHOD: Simulations investigated the effects of signal averaging on SNR, measurement error and group-level variance against a known ground truth. Relative root mean square errors (measurement error) and coefficients of variation (group-level variance) were calculated...
February 21, 2018: Journal of Neuroscience Methods
Olivia Sanchez, Andrea García, Fernando Castro-Prado, Miriam Perez, Rafael Lara-Estrada, Martin Ramirez-Meza, Montserrat Godinez, Michael L Coco, Joaquín Azpiroz, Mark K Borsody, Emilio Sacristán
BACKGROUND: Magnetic stimulation of the facial nerve has been tested in preclinical studies as a new, non-invasive emergency treatment of ischemic stroke that acts by increasing cerebral blood flow (CBF). The objective of the studies reported herein was to identify minimal stimulation parameters that increase CBF in large animals and then test those stimulation parameters in healthy volunteers for safety, tolerability, and effectiveness at increasing CBF. This translational research is necessary preparation for clinical studies in ischemic stroke patients...
February 15, 2018: Journal of Translational Medicine
A Soleimani, S H Rasta, T Banaei, A Asgharsharghi Bonab
Introduction: The aim of the present study was to determine burn intensity in retinal laser photocoagulation based on laser parameters; wavelength, power, beam size and pulse duration, using Optical Coherence Tomography (OCT), fundus camera, physical eye model and computer simulation in a clinical study. Materials and Methods: Participants were 10 adult patients between 50-80 years with proliferative diabetic retinopathy. A multicolor-photo coagulator with 532 nm green and 672 nm red for retina photocoagulation in diabetic retinopathy was used to investigate the participants...
December 2017: Journal of Biomedical Physics & Engineering
Loes G M de Kruijff, M Prins, A van der Krans, R Hoencamp, P van der Wurff
INTRODUCTION: Prior to deployment of the Netherlands Army Task Force Urozgan in Afghanistan, the Dutch Military and civilian healthcare systems had limited experience in treating blast injuries and their long-term consequences. This meant that guidelines for treatment and rehabilitation were lacking. The aim of this cohort study was to quantify kinematic and kinetic abnormalities in service members with foot injuries in relation to functional outcome using gait analysis. METHOD: In nine service members with combat-related talus, calcaneus and/or navicular bone (TCN) fractures and nine controls, gait parameters were measured using Gait Real-Time Analysis Interactive Lab system...
February 7, 2018: Journal of the Royal Army Medical Corps
Gianfranco Piccirillo, Damiano Magrì, Gaetana D'Alessandro, Claudia Fiorucci, Federica Moscucci, Claudia Di Iorio, Fabiola Mastropietri, Ilaria Parrotta, Masahiro Ogawa, Shien-Fong Lin, Peng-Sheng Chen
The relationship between autonomic nervous system (ANS) modulation of the sinus node and heart rate variability has been extensively investigated. Current study sought to evaluate, in an animal experimental model of pacing-induced tachycardia congestive heart failure (CHF), a possible ANS influence on P wave duration and PR interval oscillations. Short term (5-minutes) time and frequency domain analysis has been obtained in six dogs for the following electrocardiographic intervals: P wave duration (P), from the onset to peak of P wave (Pp), from the onset of P wave to the q onset (PR) and from the end of P wave to the onset of q wave (PeR)...
February 2, 2018: Physiological Measurement
Ankita Munjal, Joshua M Steinberg, Afnan Mossaad, Samuel J Kallus, Mark C Mattar, Nadim G Haddad
AIM: To organize post-procedure satisfaction data into a useful reference and analyze patient-centered parameters to find trends that influence patient satisfaction. METHODS: A robust database of two cohorts of outpatients that underwent an endoscopic procedure at Georgetown University Hospital at two separate three-month intervals ranging from November 2012 to January 2013 and November 2015 to January 2016 was compiled. Time of year was identical to control for weather/seasonal issues that may have contributed to the patient experience...
January 16, 2018: World Journal of Gastrointestinal Endoscopy
Mehdi Kordi, Campbell Menzies, Len Parker Simpson
PURPOSE: The curvature constant (W') and asymptote (critical power; CP) of the power-duration relationship are important parameters for explaining cycling performance. Short-duration endurance cycling events rely more heavily on the W'; however, the full mechanistic underpinning of this parameter is yet to be determined. Evidence suggests both muscle volume and muscle strength may contribute to the magnitude of W'. Therefore, the present study investigated the relationship between power-duration parameters (CP and W') and (1) anthropometric and (2) mechanical properties of thigh muscles in a sample of elite cyclists...
March 2018: European Journal of Applied Physiology
Marek Strzała, Arkadiusz Stanula, Piotr Krężałek, Andrzej Ostrowski, Marcin Kaca, Grzegorz Głąb
The aim of this study was to investigate somatic properties and force production of leg extensor muscles measured in the countermovement jump test (CMJ), as well as to analyse kinematic variables of sprint surface butterfly swimming. Thirty-four male competitive swimmers were recruited with an average age of 19.3 ± 1.83 years. Their average body height (BH) was 183.7 ± 5.93 cm, body fat content 10.8 ± 2.64% and body mass (BM) 78.3 ± 5.0 kg. Length measurements of particular body segments were taken and a counter movement jump (CMJ) as well as an all-out 50 m butterfly speed test were completed...
December 2017: Journal of Human Kinetics
Robert G Lockie, Samuel J Callaghan, Matthew R Moreno, Fabrice G Risso, Tricia M Liu, Alyssa A Stage, Samantha A Birmingham-Babauta, John J Stokes, Dominic V Giuliano, Adrina Lazar, DeShaun L Davis, Ashley J Orjalo
The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM) traditional bench press (TBP) and close-grip bench press (CGBP). Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p < 0.05) compared the 1RM and mechanical variables for the TBP and CGBP; effect sizes (d) were also calculated...
December 2017: Journal of Human Kinetics
Linda M Rose, Catherine A A Beauchemin, W Patrick Neumann
This study's objective was to develop models of endurance time (ET), as a function of load level (LL), and of resumption time (RT) after loading as a function of both LL and loading time (LT) for repeated loadings. Ten male participants with experience in construction work each performed fifteen different one-handed repetaed pushing tasks at shoulder height with varied exerted force and duration. This data was used to create regression models predicting ET and RT. It is concluded that power law relationships are most appropriate to use when modelling ET and RT...
January 11, 2018: Ergonomics
J G Messer, J L Mendieta Calle, J M Jiron, E J Castillo, C Van Poznak, N Bhattacharyya, D B Kimmel, J I Aguirre
OBJECTIVE: Investigate role of dose/duration of zoledronic acid (ZOL), a powerful anti-resorptive (pAR), on prevalence of medication-related osteonecrosis of the jaw (MRONJ) in rice rats (Oryzomys palustris), a species with natural susceptibility to food impaction-induced localized periodontitis (FILP). We hypothesize that ZOL induces MRONJ lesions in rice rats with FILP, and that the prevalence of MRONJ rises with increasing dose and duration of ZOL treatment. METHODS: We performed a toxicology experiment with clinically-relevant doses of ZOL in female rats (N=230) fed standard (STD) rodent chow...
December 28, 2017: Bone
Hiroyuki Oya, Phillip E Gander, Christopher I Petkov, Ralph Adolphs, Kirill V Nourski, Hiroto Kawasaki, Matthew A Howard, Timothy D Griffiths
Natural environments elicit both phase-locked and non-phase-locked neural responses to the stimulus in the brain. The interpretation of the BOLD signal to date has been based on an association of the non-phase-locked power of high-frequency local field potentials (LFPs), or the related spiking activity in single neurons or groups of neurons. Previous studies have not examined the prediction of the BOLD signal by phase-locked responses. We examined the relationship between the BOLD response and LFPs in the same nine human subjects from multiple corresponding points in the auditory cortex, using amplitude modulated pure tone stimuli of a duration to allow an analysis of phase locking of the sustained time period without contamination from the onset response...
December 21, 2017: NeuroImage
Christoph Triska, Bettina Karsten, Bernd Heidegger, Bernhard Koller-Zeisler, Bernhard Prinz, Alfred Nimmerichter, Harald Tschan
The purpose of this study was to assess the reliability of critical power (CP) and the total amount of work accomplished above CP (W´) across repeated tests using ecologically valid maximal effort time-trials (TT) under laboratory conditions. After an initial incremental exercise test, ten well-trained male triathletes (age: 28.5 ± 4.7 years; body mass: 73.3 ± 7.9 kg; height: 1.80 ± 0.07 m; maximal aerobic power [MAP]: 329 ± 41 W) performed three testing sessions (Familiarization, Test I and Test II) each comprising three TT (12, 7, and 3 min with a passive recovery of 60 min between trials)...
2017: PloS One
Sarah Tymchuk, Daniela Gomez, Noshin Koenig, M John Gill, Esther Fujiwara, Christopher Power
OBJECTIVE: Mood disorders and neurocognitive impairments are debilitating conditions among patients with HIV/AIDS. How these comorbidities interact and their relationships to systemic factors remain uncertain. Herein, we investigated factors contributing to depressive symptomatology (DS) in a prospective cohort of patients with HIV/AIDS in active care that included neuropsychological assessment. METHODS: Among patients with HIV/AIDS receiving combination antiretroviral therapy (cART) and ongoing clinical assessments including measures of sleep, health-related quality of life (HQoL), neuropsychological testing, and mood evaluation (Patient Health Questionnaire-9 [PHQ-9]) were performed...
January 1, 2017: Canadian Journal of Psychiatry. Revue Canadienne de Psychiatrie
Othmar Moser, Max L Eckstein, Olivia McCarthy, Rachel Deere, Stephen C Bain, Hanne L Haahr, Eric Zijlstra, Richard M Bracken
Background: To explore the impact of glycaemic control (HbA1c ) on functional capacity during cardio-pulmonary exercise testing in people with type 1 diabetes. Methods: Sixty-four individuals with type 1 diabetes (age: 34 ± 8 years; 13 females, HbA1c : 7.8 ± 1% (62 ± 13 mmol/mol), duration of diabetes: 17 ± 9 years) performed a cardio-pulmonary cycle ergometer exercise test until volitional exhaustion. Stepwise linear regression was used to explore relationships between HbA1c and cardio-respiratory data with p ≤ 0...
2017: Diabetology & Metabolic Syndrome
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