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Respiratory exchange ratio

Laurie Isacco, Ophélie Ritter, Nicolas Tordi, Davy Laroche, Bruno Degano, Malika Bouhaddi, Mark Rakobowchuk, Laurent Mourot
This study investigated substrate oxidation in concentric and eccentric cycling matched for aerobic power output in the postprandial state. Energy expenditure, respiratory exchange ratio, and fat and carbohydrate oxidation rates were measured at rest and after 15, 30, and 45 min of eccentric and concentric cycling in 12 men. Absolute and relative aerobic power output and energy expenditure were similar during concentric and eccentric exercise. No effect of exercise modality was observed for substrate metabolism...
August 11, 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Kurt A Escobar, Jacobo Morales, Trisha A Vandusseldorp
CrossFit is a metabolically demanding strength and conditioning method which performance may benefit from a carbohydrate (CHO)-rich diet. This study investigated the effect of three consecutive days of high CHO intake on CrossFit performance and corresponding metabolically -related variables in strength trained individuals. Eighteen subjects with a CHO intake of <6 g/kg/day were randomly assigned into a CHO (n = 9) or control (C) group (n =9) and underwent a 9-day training protocol. During days 1, 5, and 9, performance was measured as repetitions completed during a 12 minute CrossFit workout...
2016: International Journal of Exercise Science
Kevin Forton, Yoshiki Motoji, Gael Deboeck, Vitalie Faoro, Robert Naeije
There has been revival of in interest in exercise testing of the pulmonary circulation for the diagnosis of pulmonary vascular disease, but there still is uncertainty about body position and the most relevant measurements. Doppler echocardiography pulmonary hemodynamic measurements were performed at progressively increased workload in 26 healthy adult volunteers in supine, semi-recumbent and upright positions which were randomly assigned at 24 hours intervals. Mean pulmonary artery pressure (mPAP) was estimated from the maximum tricuspid regurgitation jet velocity...
October 7, 2016: Journal of Applied Physiology
Nastasia Marinus, Liene Bervoets, Guy Massa, Kenneth Verboven, An Stevens, Tim Takken, Dominique Hansen
BACKGROUND: Cardiopulmonary exercise testing is advised ahead of exercise intervention in obese adolescents to assess medical safety of exercise and physical fitness. Optimal validity and reliability of test results are required to identify maximal exercise effort. As fat oxidation during exercise is disturbed in obese individuals, it remains an unresolved methodological issue whether the respiratory gas exchange ratio (RER) is a valid marker for maximal effort during exercise testing in this population...
October 20, 2016: Journal of Sports Medicine and Physical Fitness
Gisele de A Padilha, Lucas F B Horta, Lillian Moraes, Cassia L Braga, Milena V Oliveira, Cíntia L Santos, Isalira P Ramos, Marcelo M Morales, Vera Luiza Capelozzi, Regina C S Goldenberg, Marcelo Gama de Abreu, Paolo Pelosi, Pedro L Silva, Patricia R M Rocco
BACKGROUND: In patients with emphysema, invasive mechanical ventilation settings should be adjusted to minimize hyperinflation while reducing respiratory effort and providing adequate gas exchange. We evaluated the impact of pressure-controlled ventilation (PCV) and pressure support ventilation (PSV) on pulmonary and diaphragmatic damage, as well as cardiac function, in experimental emphysema. METHODS: Emphysema was induced by intratracheal instillation of porcine pancreatic elastase in Wistar rats, once weekly for 4 weeks...
December 2016: Intensive Care Medicine Experimental
Raoyrin Chanavirut, Pattarapong Makarawate, Ian A Macdonald, Naruemon Leelayuwat
BACKGROUND: Imbalances of the autonomic nervous (ANS), the cardiovascular system, and ionics might contribute to the manifestation of The Brugada Syndrome (BrS). Thus, this study has aimed to investigate the cardio-respiratory fitness and the responses of the ANS both at rest and during a sub-maximal exercise stress test, in BrS patients and in gender-matched and age-matched healthy sedentary controls. METHODS: Eleven BrS patients and 23 healthy controls were recruited in Khon Kaen, Thailand...
October 2016: Journal of Arrhythmia
Hailee L Wingfield, Abbie E Smith-Ryan, Malia N Melvin, Erica J Roelofs, Eric T Trexler, Anthony C Hackney, Mark A Weaver, Eric D Ryan
BACKGROUND: The purpose of this study was to examine the effect of exercise modality and pre-exercise carbohydrate (CHO) or protein (PRO) ingestion on post-exercise resting energy expenditure (REE) and respiratory exchange ratio (RER) in women. METHODS: Twenty recreationally active women (mean ± SD; age 24.6 ± 3.9 years; height 164.4 ± 6.6 cm; weight 62.7 ± 6.6 kg) participated in this randomized, crossover, double-blind study. Each participant completed six exercise sessions, consisting of three exercise modalities: aerobic endurance exercise (AEE), high-intensity interval running (HIIT), and high-intensity resistance training (HIRT); and two acute nutritional interventions: CHO and PRO...
December 2015: Sports Medicine—Open
Katie R Hirsch, Abbie E Smith-Ryan, Malia N M Blue, Meredith G Mock, Eric T Trexler, Kristin S Ondrak
OBJECTIVES: Traditional evaluations of metabolic health may overlook underlying dysfunction in individuals who show no signs of insulin resistance or dyslipidemia. The purpose of this study was to characterize metabolic health in overweight and obese adults using traditional and non-traditional cardiometabolic variables. A secondary purpose was to evaluate differences between overweight/obese and male/female cohorts, respectively. METHODS: Forty-nine overweight and obese adults (Mean ± SD; Age=35...
October 13, 2016: Physician and Sportsmedicine
James P Gavin, Stephen D Myers, Mark E Willems
BACKGROUND: We examined the effect of early-onset of muscle damage and low muscle glycogen on cardiorespiratory and metabolic responses to low-intensity exercise. METHODS: Twelve men cycled for 10 min at 50% maximal oxygen uptake before, and 12 h after a morning downhill run (five, 8 min bouts at -12% gradient, with 2 min rests) under normal (NORM) and lowered glycogen (LOW) conditions, following a cross-over design with conditions separated by six weeks. Cardiorespiratory responses were recorded, with oxidation measures derived from stoichiometry equations...
October 11, 2016: Journal of Sports Medicine and Physical Fitness
James M Green, Alyssa Olenick, Caroline Eastep, Lee Winchester
Caffeine (CAF) blunts estimated ratings of perceived exertion (RPE) but the effects on RPE production are unclear. This study examined effects of acute caffeine ingestion during treadmill exercise where participants exercised at prescribed RPE 4 and 7. Recreational runners (maximal oxygen consumption = 51.4 ± 9.8 mL·kg(-1)·min(-1)) (n = 16) completed a maximal treadmill test followed by trials where they selected treadmill velocity (VEL) (1% grade) to produce RPE 4 and RPE 7 (10 min each). RPE production trials followed CAF (6 mg·kg(-1)) or placebo (PLA) (counterbalanced) ingestion...
June 30, 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
Pablo H H Lopez, Susan Aja, Kazuhiro Aoki, Marcus M Seldin, Xia Lei, Gabriele V Ronnett, G William Wong, Ronald L Schnaar
Sialyltransferases are a family of 20 gene products in mice and humans that transfer sialic acid from its activated precursor, CMP-sialic acid, to the terminus of glycoprotein and glycolipid acceptors. ST3Gal-II (coded by the St3gal2 gene) transfers sialic acid preferentially to the 3-position of galactose on the Galβ1-3GalNAc terminus of gangliosides GM1 and GD1b to synthesize GD1a and GT1b respectively. Mice with a targeted disruption of St3gal2 unexpectedly displayed late-onset obesity and insulin resistance...
September 28, 2016: Glycobiology
Catriona A Burdon, Inge Spronk, Hoi Lun Cheng, Helen T O'Connor
BACKGROUND: Low glycemic index (GI) pre-exercise meals may enhance endurance performance by maintaining euglycemia and altering fuel utilization. However, evidence for performance benefits is equivocal. OBJECTIVE: To evaluate the effect of a low GI (LGI) versus a high GI (HGI) pre-exercise meal on endurance performance using meta-analyses. METHODS: Data sources included MEDLINE, SPORTDiscus, AUSPORT, AusportMed, Web of Science, and Scopus...
September 28, 2016: Sports Medicine
Kenneth J Hunt, Prasanna Anandakumaran, Jonas A Loretz, Jittima Saengsuwan
PURPOSE: Self-paced maximal testing methods may be able to exploit central mediation of function-limiting fatigue and therefore have potential to generate more valid estimates of peak oxygen uptake. The aim of this study was to investigate the feasibility of a new method for self-paced peak performance testing on treadmills and to compare peak and submaximal performance outcomes with those obtained using a non-self-paced ('computer-paced') method employing predetermined speed and slope profiles...
September 28, 2016: Clinical Physiology and Functional Imaging
Christopher Lotz, Norbert Roewer, Ralf M Muellenbach
Mechanical ventilation is the most commonly used form of respiratory support to restore or maintain adequate gas exchange. However, mechanical ventilation does not provide a physiological form of breathing. Neither does it provide an optimal ventilation / perfusion ratio due to passive movement of the diagphragm favoring the non-dependent parts of the lung. Furthermore, patients are in danger of ventilator-associated/induced lung injury (VALI/VILI). Hence, lung protective ventilation is mandatory in patients with an acute respiratory distress syndrome (ARDS) and should likewise be used in the operating room...
September 2016: Anästhesiologie, Intensivmedizin, Notfallmedizin, Schmerztherapie: AINS
Mohamed Ayachi, Romain Niel, Iman Momken, Véronique L Billat, Laurence Mille-Hamard
In the field of comparative physiology, it remains to be established whether the concept of VO2max is valid in the mouse and, if so, how this value can be accurately determined. In humans, VO2max is generally considered to correspond to the plateau observed when VO2 no longer rises with an increase in workload. In contrast, the concept of VO2peak tends to be used in murine studies. The objectives of the present study were to determine whether (i) a continuous ramp protocol yielded a higher VO2peak than a stepwise, incremental protocol, and (ii) the VO2peak measured in the ramp protocol corresponded to VO2max...
2016: Frontiers in Physiology
Christian Lind Malte, Hans Malte, Tobias Wang
Animals with intermittent lung ventilation and those exposed to hypoxia and hypercapnia will experience fluctuations in the bodily O2 and CO2 stores, but the magnitude and temporal duration of these changes are not well understood amongst ectotherms. Using the changes in the respiratory exchange ratio (RER, CO2 excretion divided by O2 uptake) as a proxy for changes in bodily gas stores, we quantified time constants in response to hypoxia and hypercapnia in Cuvier's dwarf caiman. We confirm distinct and prolonged changes in RER during and after exposure to hypoxia or hypercapnia...
September 12, 2016: Journal of Experimental Biology
Yvonne Kilian, Florian Engel, Patrick Wahl, Silvia Achtzehn, Billy Sperlich, Joachim Mester
PURPOSE: The aim of the present study was to compare the effects of high-intensity interval training (HIIT) vs high-volume training (HVT) on salivary stress markers [cortisol (sC), testosterone (sT), alpha-amylase (sAA)], metabolic and cardiorespiratory response in young athletes. METHODS: Twelve young male cyclists (14 ± 1 years; 57.9 ± 9.4 mL min(-1) kg(-1) peak oxygen uptake) performed one session of HIIT (4 × 4 min intervals at 90-95 % peak power output separated by 3 min of active rest) and one session of HVT (90 min constant load at 60 % peak power output)...
September 10, 2016: European Journal of Applied Physiology
Matthieu Jabaudon, Pierre Boucher, Etienne Imhoff, Russell Chabanne, Jean-Sébastien Faure, Laurence Roszyk, Sandrine Thibault, Raiko Blondonnet, Gael Clairefond, Renaud Guérin, Sébastien Perbet, Sophie Cayot, Thomas Godet, Bruno Pereira, Vincent Sapin, Jean-Etienne Bazin, Emmanuel Futier, Jean-Michel Constantin
RATIONALE: Sevoflurane improves gas exchange, reduces alveolar edema and inflammation in preclinical studies of lung injury but its therapeutic effects have never been investigated in acute respiratory distress syndrome (ARDS). OBJECTIVES: To assess whether sevoflurane would improve gas exchange and inflammation in ARDS. METHODS: We did a parallel, open-label single center randomized controlled trial at 3 intensive care units from a french university hospital between April, 2014, and February, 2016...
September 9, 2016: American Journal of Respiratory and Critical Care Medicine
Matthew A Wyon, Nick Allen, Ross Cloak, Sarah Beck, Paul Davies, Frances Clarke
An athlete's cardiorespiratory profile, maximal aerobic capacity, and anaerobic threshold is affected by training regimen and competition demands. The present study aimed to ascertain whether there are company rank differences in maximal aerobic capacity and anaerobic threshold in elite classical ballet dancers. Seventy-four volunteers (M 34, F 40) were recruited from two full-time professional classical ballet companies. All participants completed a continuous incremental treadmill protocol with a 1-km/hr speed increase at the end of each 1-min stage until termination criteria had been achieved (e...
September 2016: Medical Problems of Performing Artists
Hernan Aguirre-Bermeo, Indalecio Morán, Maurizio Bottiroli, Stefano Italiano, Francisco José Parrilla, Eugenia Plazolles, Ferran Roche-Campo, Jordi Mancebo
BACKGROUND: End-inspiratory pause (EIP) prolongation decreases dead space-to-tidal volume ratio (Vd/Vt) and PaCO2. We do not know the physiological benefits of this approach to improve respiratory system mechanics in acute respiratory distress syndrome (ARDS) patients when mild hypercapnia is of no concern. METHODS: The investigation was conducted in an intensive care unit of a university hospital, and 13 ARDS patients were included. The study was designed in three phases...
December 2016: Annals of Intensive Care
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