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Ventilatory threshold

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https://www.readbyqxmd.com/read/29040646/statins-affect-skeletal-muscle-performance-evidence-for-disturbances-in-energy-metabolism
#1
Neeltje A E Allard, Tom J J Schirris, Rebecca J Verheggen, Frans G M Russel, Richard J Rodenburg, Jan A M Smeitink, Paul D Thompson, Maria T E Hopman, Silvie Timmers
Context: Statin myopathy is linked to disturbances in mitochondrial function and exercise intolerance. Objectives: To determine whether differences exist in exercise performance, muscle function and mitochondrial oxidative capacity and content between symptomatic and asymptomatic statin users, and non-statin using controls. Design: Cross-sectional study. Setting: Department of Physiology of the Radboud University Medical Center...
October 9, 2017: Journal of Clinical Endocrinology and Metabolism
https://www.readbyqxmd.com/read/29036765/development-of-an-anaerobic-threshold-hrlt-hrvt-estimation-equation-using-the-heart-rate-threshold-hrt-during-the-treadmill-incremental-exercise-test
#2
Joo-Ho Ham, Hun-Young Park, Youn-Ho Kim, Sang-Kon Bae, Byung-Hoon Ko, Sang-Seok Nam
PURPOSE: The purpose of this study was to develop a regression model to estimate the heart rate at the lactate threshold (HRLT) and the heart rate at the ventilatory threshold (HRVT) using the heart rate threshold (HRT), and to test the validity of the regression model. METHODS: We performed a graded exercise test with a treadmill in 220 normal individuals (men: 112, women: 108) aged 20-59 years. HRT, HRLT, and HRVT were measured in all subjects. A regression model was developed to estimate HRLT and HRVT using HRT with 70% of the data (men: 79, women: 76) through randomization (7:3), with the Bernoulli trial...
September 30, 2017: Journal of Exercise Nutrition & Biochemistry
https://www.readbyqxmd.com/read/29029283/trajectories-of-cardiorespiratory-fitness-in-patients-with-juvenile-dermatomyositis
#3
Kiki J Blom, Tim Takken, Barbara C H Huijgen, Judith Wienke, Annet van Royen-Kerkhof, Marco van Brussel
Objectives: Previous research demonstrated decreased cardiorespiratory fitness (CRF) in patients with JDM during active disease and remission. However, longitudinal data regarding trajectories of CRF are currently lacking. The objective of this study was to determine trajectories of CRF in patients with both monocyclic and chronic JDM, and to identify potential predictors of these trajectories. Methods: Thirty-six patients with JDM [median age (interquartile range) at diagnosis: 8...
September 27, 2017: Rheumatology
https://www.readbyqxmd.com/read/29025898/aging-is-associated-with-increased-propensity-for-central-apnea-during-nrem-sleep
#4
Susmita Chowdhuri, Sukanya Pranathiageswaran, Hillary Loomis-King, Anan Salloum, M Safwan Badr
The reason for increased sleep disordered breathing with predominance of central apneas in the elderly is unknown. We hypothesized that the propensity to central apneas is increased in older adults, manifested by a reduced carbon-dioxide (CO2) reserve in older compared to young adults during non-REM (NREM) sleep. METHODS: 10 elderly and 15 young healthy adults underwent multiple brief trials of nasal noninvasive positive pressure ventilation during stable NREM sleep. Cessation of mechanical ventilation (MV) resulted in hypocapnic central apnea or hypopnea...
October 12, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29018361/new-methods-for-processing-and-quantifying-vo2-kinetics-to-steady-state-vo2-onset-kinetics
#5
Craig R McNulty, Robert A Robergs
Current methods of oxygen uptake (VO2) kinetics data handling may be too simplistic for the complex physiology involved in the underlying physiological processes. Therefore, the aim of this study was to quantify the VO2 kinetics to steady state across the full range of sub-ventilatory threshold work rates, with a particular focus on the VO2 onset kinetics. Ten healthy, moderately trained males participated in five bouts of cycling. Each bout involved 10 min at a percentage of the subject's ventilation threshold (30, 45, 60, 75, 90%) from unloaded cycling...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28992936/-short-term-exercise-based-cardiac-rehabilitation-induced-changes-in-cardiorespiratory-mechanical-and-neuromuscular-responses-to-progressive-exercise-testing
#6
P-M Leprêtre, M Ghannem, S Delanaud, N Jaunet, L Gaillard, A Barnabé, T Porcher, T Weissland
Previous studies showed that changes in peak of oxygen uptake value (VO2peak) with training were poorly related to changes in Maximal Tolerated Power output (MTP) among patients with cardiovascular disease. This result could be due to a difference between cardiopulmonary adaptation to training and the skeletal muscle conditioning. OBJECTIVE: The aim of the study was to compare the responses to exercise training of electromyographic activities of vastus lateralis (rms-EMG) and respiratory parameters...
October 6, 2017: Annales de Cardiologie et D'angéiologie
https://www.readbyqxmd.com/read/28989117/brachial-artery-blood-flow-dynamics-during-sinusoidal-leg-cycling-exercise-in-humans
#7
Yoshiyuki Fukuba, Masako Y Endo, Ayaka Kondo, Yuka Kikugawa, Kohei Miura, Hideaki Kashima, Masaki Fujimoto, Naoyuki Hayashi, Yoshiyuki Fukuoka, Shunsaku Koga
To explore the control of the peripheral circulation of a nonworking upper limb during leg cycling exercise, blood flow (BF) dynamics in the brachial artery (BA) were determined using a sinusoidal work rate (WR) exercise. Ten healthy subjects performed upright leg cycling exercise at a constant WR for 30 min, followed by 16 min of sinusoidal WR consisting of 4-min periods of WR fluctuating between a minimum output of 20 W and a maximum output corresponding to ventilatory threshold (VT). Throughout the protocol, pulmonary gas exchange, heart rate (HR), mean arterial blood pressure (MAP), blood velocity (BV), and cross-sectional area of the BA, forearm skin BF (SBF), and sweating rate (SR) were measured...
October 2017: Physiological Reports
https://www.readbyqxmd.com/read/28985727/respiratory-mechanics-in-infants-with-severe-bronchiolitis-on-controlled-mechanical-ventilation
#8
Pablo Cruces, Sebastián González-Dambrauskas, Julio Quilodrán, Jorge Valenzuela, Javier Martínez, Natalia Rivero, Pablo Arias, Franco Díaz
BACKGROUND: Analysis of respiratory mechanics during mechanical ventilation (MV) is able to estimate resistive, elastic and inertial components of the working pressure of the respiratory system. Our aim was to discriminate the components of the working pressure of the respiratory system in infants on MV with severe bronchiolitis admitted to two PICU's. METHODS: Infants younger than 1 year old with acute respiratory failure caused by severe bronchiolitis underwent neuromuscular blockade, tracheal intubation and volume controlled MV...
October 6, 2017: BMC Pulmonary Medicine
https://www.readbyqxmd.com/read/28970805/quadriceps-muscles-o2-extraction-and-emg-breakpoints-during-a-ramp-incremental-test
#9
Danilo Iannetta, Ahmad Qahtani, Guillaume Y Millet, Juan M Murias
Muscle deoxygenated breakpoint ([HHb]BP) has been found to be associated with other indices of exercise tolerance in the vastus lateralis (VL) muscle but not in the vastus medialis (VM) and rectus femoris (RF). Purpose: To investigate whether the [HHb]BP occurs also in the VM and RF muscles and whether or not it is associated with other physiological indices of exercise tolerance, such as the EMG threshold (EMGt) and the respiratory compensation point (RCP). Methods: Twelve young endurance trained participants performed maximal ramp incremental (RI) cycling tests (25-30 W·min(-1) increments)...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28953985/relationship-between-aerobic-capacity-and-pelvic-floor-muscles-function-a-cross-sectional-study
#10
S P Jürgensen, A Borghi-Silva, A M F G Bastos, G N Correia, V S Pereira-Baldon, R Cabiddu, A M Catai, P Driusso
The objective of this study was to evaluate the relationship between aerobic capacity and pelvic floor muscles (PFM) function in adult women. Women aged 18 or over and without urinary dysfunction or other chronic diseases were eligible to participate. They completed the habitual physical activity (HPA) questionnaire, underwent a PFM functional evaluation by palpation and perineometry, and performed a submaximal (between 75 and 85% of maximum heart rate) cardiopulmonary exercise (CPX) test to determine the ventilatory anaerobic threshold (VAT)...
September 21, 2017: Brazilian Journal of Medical and Biological Research, Revista Brasileira de Pesquisas Médicas e Biológicas
https://www.readbyqxmd.com/read/28885281/correlation-between-exercise-capacity-and-quality-of-life-in-patients-with-cardiac-disease
#11
Karoline Stentoft Andersen, Sussie Laustsen, Annemette Krintel Petersen
PURPOSE: Patients are referred to exercise-based cardiac rehabilitation (ECR) to increase exercise capacity and health-related quality of life (HRQOL) and thereby reduce risk of morbidity and mortality. The purpose of this study was to examine the correlation between exercise capacity and HRQOL. Furthermore, this study examined whether improvements in HRQOL were directly related to improvements in exercise capacity. METHODS: The study included 277 patients participating in ECR...
September 6, 2017: Journal of Cardiopulmonary Rehabilitation and Prevention
https://www.readbyqxmd.com/read/28878694/physiological-responses-to-firefighting-in-extreme-temperatures-do-not-compare-to-firefighting-in-temperate-conditions
#12
Stephanie Windisch, Wolfgang Seiberl, Daniel Hahn, Ansgar Schwirtz
Purpose: The aim of this study was to examine physiological responses to two different simulated firefighting exercises: a firefighting exercise with flashovers, smoke, poor visibility and extreme temperatures (300°) in a burning container and a standard firefighting exercise in temperate conditions. Furthermore, a second purpose of the study was to find out if the contribution of strength and endurance capacities to firefighting performance changes when the demands of the firefighting exercise change. Methods: Sixteen professional firefighters performed a maximum treadmill test, strength testing, a standard simulated firefighting exercise (SFE) without heat and flashovers and a firefighting exercise with a simulation of the flashover phenomenon in a burning container (FOT)...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28875971/-exercise-capacity-in-patients-with-pulmonary-sarcoidosis
#13
Justyna Błaut-Jurkowska, Klaudia Knap, Magdalena Kaźnica-Wiatr, Agnieszka Żygadło, Lidia Tomkiewicz-Pająk, Piotr Podolec, Maria Olszowska
Exertional dyspnea is a common manifestation of sarcoidosis. Cardiopulmonary exercise testing (CPET) is a useful tool to evaluate exercise tolerance of sarcoid patients. AIM: The aim of the study was to evaluate of exercise capacity in patients with pulmonary sarcoidosis with regard to duration of the disease. Analysis of differences in physical tolerance between patients with cardiac sarcoidosis and without cardiac sarcoidosis. MATERIALS AND METHODS: 39 patients diagnosed with pulmonary sarcoidosis were enrolled to our study...
August 21, 2017: Polski Merkuriusz Lekarski: Organ Polskiego Towarzystwa Lekarskiego
https://www.readbyqxmd.com/read/28869746/physiological-intensity-profile-exercise-load-and-performance-predictors-of-a-65-km-mountain-ultra-marathon
#14
Alessandro Fornasiero, Aldo Savoldelli, Damiano Fruet, Gennaro Boccia, Barbara Pellegrini, Federico Schena
The aims of the study were to describe the physiological profile of a 65-km (4000-m cumulative elevation gain) running mountain ultra-marathon (MUM) and to identify predictors of MUM performance. Twenty-three amateur trail-runners performed anthropometric evaluations and an uphill graded exercise test (GXT) for VO2max, ventilatory thresholds (VTs), power outputs (PMax, PVTs) and heart rate response (HRmax, HR@VTs). Heart rate (HR) was monitored during the race and intensity was expressed as: Zone I (<VT1), Zone II (VT1-VT2), Zone III (>VT2) for exercise load calculation (training impulse, TRIMP)...
September 4, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28838335/comparative-determination-of-ventilatory-efficiency-from-constant-load-and-incremental-exercise-testing
#15
S Algul, F A Ugur, A Ayar, O Ozcelik
The analysis of the relationships between minute ventilation (VE) to CO2 output (VCO2), referred to as ventilatory efficiency, in response to incremental exercise testing, is considered a useful index for assessing the presence and severity of cardiopulmonary and metabolic diseases. The effects of constant load exercise testing performed at work intensity associated with anaerobic threshold (AT) and respiratory compensation points (RCP), on the accurate measurements of ventilatory efficiency are not well known...
August 15, 2017: Cellular and Molecular Biology
https://www.readbyqxmd.com/read/28819793/the-mechanisms-underlying-the-production-of-discontinuous-gas-exchange-cycles-in-insects
#16
REVIEW
Philip G D Matthews
This review examines the control of gas exchange in insects, specifically examining what mechanisms could explain the emergence of discontinuous gas exchange cycles (DGCs). DGCs are gas exchange patterns consisting of alternating breath-hold periods and bouts of gas exchange. While all insects are capable of displaying a continuous pattern of gas exchange, this episodic pattern is known to occur within only some groups of insects and then only sporadically or during certain phases of their life cycle. Investigations into DGCs have tended to emphasise the role of chemosensory thresholds in triggering spiracle opening as critical for producing these gas exchange patterns...
August 17, 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
https://www.readbyqxmd.com/read/28818154/physiology-based-modeling-may-predict-surgical-treatment-outcome-for-obstructive-sleep-apnea
#17
Yanru Li, Jingying Ye, Demin Han, Xin Cao, Xiu Ding, Yuhuan Zhang, Wen Xu, Jeremy Orr, Rachel Jen, Scott Sands, Atul Malhotra, Robert Owens
STUDY OBJECTIVES: To test whether the integration of both anatomical and nonanatomical parameters (ventilatory control, arousal threshold, muscle responsiveness) in a physiology-based model will improve the ability to predict outcomes after upper airway surgery for obstructive sleep apnea (OSA). METHODS: In 31 patients who underwent upper airway surgery for OSA, loop gain and arousal threshold were calculated from preoperative polysomnography (PSG). Three models were compared: (1) a multiple regression based on an extensive list of PSG parameters alone; (2) a multivariate regression using PSG parameters plus PSG-derived estimates of loop gain, arousal threshold, and other trait surrogates; (3) a physiological model incorporating selected variables as surrogates of anatomical and nonanatomical traits important for OSA pathogenesis...
September 15, 2017: Journal of Clinical Sleep Medicine: JCSM: Official Publication of the American Academy of Sleep Medicine
https://www.readbyqxmd.com/read/28816504/validity-and-reliability-of-the-3-min-all-out-running-test-to-measure-critical-velocity-in-hot-environments
#18
Yu-Hsuan Kuo, Ching-Feng Cheng, Wei-Chieh Hsu, Del P Wong
This study's aim was to investigate the test-retest reliability of the 3-min all-out running test (3MRT) in hot environments. Twelve male sprinters (age 21.2 ± 1.8 years; height 1.78 ± 0.01 m; weight 71.0 ± 1.6 kg; [Formula: see text] 55.0 ± 1.0 mL kg(-1) min(-1)) performed an incremental exercise test in a laboratory, during which the first and second ventilatory thresholds (VT1 and VT2) and [Formula: see text] were determined. In addition, they performed two 3MRTs on an outdoor track in a hot environment, during which the critical velocity (CV) and anaerobic capacity (D') were estimated...
August 17, 2017: Research in Sports Medicine
https://www.readbyqxmd.com/read/28805258/impact-of-beta-blockers-on-cardiopulmonary-exercise-testing-in-patients-with-advanced-liver-disease
#19
M P Wallen, A Hall, K A Dias, J S Ramos, S E Keating, A J Woodward, T L Skinner, G A Macdonald, R Arena, J S Coombes
BACKGROUND: Patients with advanced liver disease may develop portal hypertension that can result in variceal haemorrhage. Beta-blockers reduce portal pressure and minimise haemorrhage risk. These medications may attenuate measures of cardiopulmonary performance, such as the ventilatory threshold and peak oxygen uptake measured via cardiopulmonary exercise testing. AIM: To determine the effect of beta-blockers on cardiopulmonary exercise testing variables in patients with advanced liver disease...
August 14, 2017: Alimentary Pharmacology & Therapeutics
https://www.readbyqxmd.com/read/28750585/nutritional-ketone-salts-increase-fat-oxidation-but-impair-high-intensity-exercise-performance-in-healthy-adult-males
#20
Trevor O'Malley, Etienne Myette-Cote, Cody Durrer, Jonathan P Little
This study investigated the impact of raising plasma beta-hydroxybutyrate (β-OHB) through ingestion of ketone salts on substrate oxidation and performance during cycling exercise. Ten healthy adult males (age, 23 ± 3 years; body mass index, 25 ± 3 kg/m(2), peak oxygen uptake, 45 ± 10 mL/(kg·min)(-1)) were recruited to complete 2 experimental trials. Before enrollment in the experimental conditions, baseline anthropometrics and cardiorespiratory fitness (peak oxygen uptake) were assessed and familiarization to the study protocol was provided...
July 27, 2017: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
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