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Respiratory exchange ratio in performance

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https://www.readbyqxmd.com/read/29626373/sex-dimorphism-of-substrate-utilization-differences-in-skeletal-muscle-mitochondrial-volume-density-and-function
#1
David Montero, Klavs Madsen, Anne-Kristine Meinild-Lundby, Fredrik Edin, Carsten Lundby
Fat oxidation during exercise is higher in females than males. We sought to determine whether sex differences in substrate metabolism are paralleled by distinct skeletal muscle mitochondrial volume density and oxidative capacity. Whole-body substrate (fat, carbohydrate (CHO)) utilization during submaximal treadmill running was assessed and skeletal muscle biopsies were taken to determine mitochondrial volume density (MitoVD ) and function in healthy young females (n = 12) and males (n = 12) matched by aerobic exercise capacity (VO2max ) and exercise performance...
April 6, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29564844/effects-of-high-intensity-warm-ups-on-running-performance
#2
Fernando González-Mohíno, Raúl Martín, Daniel Juárez Santos-García, Pedro Angel Fidel, Francisco de Asis Fernandez, Inmaculada Yustres, José María González Ravé
The objective of this study was to determine the effects of high-intensity warm-ups (WUs) on performance, physiological, neuromuscular and biomechanical parameters. Three randomized cross-over 105%vVO2 max time limit trials (TLimT) were performed by 11 well-trained runners following three different WU protocols. These included two experimental high-intensity variants and one control WU variant: (i) 9x20-sec level strides (105%vVO2 max; 1% gradient) with 60 s of recovery (level); (ii) 6x6-sec uphill strides (105%vVO2 max; 5% gradient), with the same recovery (uphill) and (iii) 7 min at 60%vVO2 max as control condition (control)...
March 21, 2018: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/29541331/the-effect-of-acute-l-carnitine-and-carbohydrate-intake-on-cycling-performance
#3
Boe M Burrus, Brian M Moscicki, Tracey D Matthews, Vincent J Paolone
Chronic supplementation of L-carnitine and carbohydrate has been reported to increase L-carnitine content in skeletal muscle and have positive influences on exercise variables and performance. This study investigated the acute intake of L-carnitine and carbohydrate on the exercise parameters of cycling. A total of 10 males (27.0 ± 4 years) completed two exercise sessions consisting of 40 min of cycling at 65% of VO2peak , followed by cycling to exhaustion at 85% of VO2peak . L-carnitine or a placebo was consumed 3 hours prior to exercise, and beverages consisting of 94 g of carbohydrate were consumed at both 2 hours, and 30 minutes prior to exercise...
2018: International Journal of Exercise Science
https://www.readbyqxmd.com/read/29535588/carbohydrate-mouth-rinse-improves-cycling-time-trial-performance-without-altering-plasma-insulin-concentration
#4
Kevin O Murray, Hunter L Paris, Alyce D Fly, Robert F Chapman, Timothy D Mickleborough
Rinsing the mouth with a carbohydrate solution has been shown to improve exercise performance in a manner similar to carbohydrate ingestion. However, the underlying mechanisms behind these ergogenic benefits remain unclear. This study evaluated whether rinsing the mouth with a carbohydrate solution alters plasma insulin and glucose concentration during the initial stages of a 40 km cycling time-trial. Eight trained, competitive cyclists [age (mean ± SEM) = 24 ± 2 y; V̇O2 max = 64.5 ± 2.2 ml·kg-1 ·min-1 ] completed three simulated 40 km time-trials comprised of a familiarization trial, a carbohydrate condition (CHO) and a placebo mouth rinse condition (PLA)...
March 2018: Journal of Sports Science & Medicine
https://www.readbyqxmd.com/read/29523922/a-novel-mechanism-for-improved-exercise-performance-in-pediatric-fontan-patients-after-cardiac-rehabilitation
#5
Samuel Wittekind, Wayne Mays, Yvette Gerdes, Sandra Knecht, John Hambrook, William Border, John Lynn Jefferies
Patients with a Fontan circulation have impaired exercise capacity. Cardiac rehabilitation (CR) has shown promise in enhancing peak exercise parameters in this population, but an improvement in submaximal exercise has not been consistently demonstrated. We assessed the hypothesis that participation in CR will be associated with more efficient oxygen extraction and ventilation during submaximal exercise. In this prospective study, pediatric Fontans completed two 60 min CR sessions per week for 12 weeks. Cardiopulmonary exercise testing and stress echocardiography were performed at baseline and last CR session, and then compared with a paired sample t test...
March 9, 2018: Pediatric Cardiology
https://www.readbyqxmd.com/read/29506981/reference-values-for-peak-oxygen-uptake-cross-sectional-analysis-of-cycle-ergometry-based-cardiopulmonary-exercise-tests-of-10-090-adult-german-volunteers-from-the-prevention-first-registry
#6
Daniel Rapp, Jürgen Scharhag, Stefan Wagenpfeil, Johannes Scholl
OBJECTIVE: This study aims to construct quantile reference values for peak oxygen uptake (V̇O2peak ) measured by cycle ergometry-based incremental cardiopulmonary exercise tests. DESIGN: Cross-sectional study using quantile regressions to fit sex-specific and age-specific quantile curves. Exercise tests were conducted using cycle ergometry. Maximal effort in the exercise tests wass assumed when respiratory exchange ratio  ≥1.1 or lactate ≥8 mmol/L or maximal heart rate ≥90% of the age-predicted maximal heart rate...
March 5, 2018: BMJ Open
https://www.readbyqxmd.com/read/29489721/post-exercise-ingestion-of-low-or-high-molecular-weight-glucose-polymer-solution-does-not-improve-cycle-performance-in-female-athletes
#7
Meredith G Mock, Katie R Hirsch, Malia N M Blue, Eric T Trexler, Erica J Roelofs, Abbie E Smith-Ryan
The current study sought to evaluate the effects of post-exercise ingestion of a high molecular weight glucose polymer solution (HMW) compared to an isocaloric low molecular weight solution (LMW) or placebo (PLA) on subsequent cycling performance in female athletes. In a randomized, double-blind, placebo-controlled, cross-over design, 10 competitive female cyclists (Mean ± SD; Age = 25.7 ± 5.0 yrs; VO2peak = 49.7 ± 4.3 ml[BULLET OPERATOR]kg[BULLET OPERATOR]min) completed three testing sessions separated by 7-10 days...
February 27, 2018: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/29485903/metabolic-and-molecular-framework-for-the-enhancement-of-endurance-by-intermittent-food-deprivation
#8
Krisztina Marosi, Keelin Moehl, Ignacio Navas-Enamorado, Sarah J Mitchell, Yongqing Zhang, Elin Lehrmann, Miguel A Aon, Sonia Cortassa, Kevin G Becker, Mark P Mattson
Evolutionary considerations suggest that the body has been optimized to perform at a high level in the food-deprived state when fatty acids and their ketone metabolites are a major fuel source for muscle cells. Because controlled food deprivation in laboratory animals and intermittent energy restriction in humans is a potent physiologic stimulus for ketosis, we designed a study to determine the impact of intermittent food deprivation during endurance training on performance and to elucidate the underlying cellular and molecular mechanisms...
February 27, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/29479563/imaging-lung-cancer-by-using-chemical-exchange-saturation-transfer-mri-with-retrospective-respiration-gating
#9
Kyle M Jones, Carol A Stuehm, Charles C Hsu, Phillip H Kuo, Mark D Pagel, Edward A Randtke
Performing chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) in lung tissue is difficult because of motion artifacts. We, therefore, developed a CEST MRI acquisition and analysis method that performs retrospective respiration gating. Our method used an acquisition scheme with a short 200-millisecond saturation pulse that can accommodate the timing of the breathing cycle, and with saturation applied at frequencies in 0.03-ppm intervals. The Fourier transform of each image was used to calculate the difference in phase angle between adjacent pixels in the longitudinal direction of the respiratory motion...
December 2017: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/29371106/cardiorespiratory-demand-and-rate-of-perceived-exertion-during-overground-walking-with-a-robotic-exoskeleton-in-long-term-manual-wheelchair-users-with-chronic-spinal-cord-injury-a-cross-sectional-study
#10
Manuel J Escalona, Rachel Brosseau, Martin Vermette, Alain Steve Comtois, Cyril Duclos, Mylène Aubertin-Leheudre, Dany H Gagnon
BACKGROUND: Many wheelchair users adopt a sedentary lifestyle, which results in progressive physical deconditioning with increased risk of musculoskeletal, cardiovascular and endocrine/metabolic morbidity and mortality. Engaging in a walking program with an overground robotic exoskeleton may be an effective strategy for mitigating these potential negative health consequences and optimizing fitness in this population. However, additional research is warranted to inform the development of adapted physical activity programs incorporating this technology...
January 22, 2018: Annals of Physical and Rehabilitation Medicine
https://www.readbyqxmd.com/read/29364063/impact-of-carbohydrate-mouth-rinsing-on-time-to-exhaustion-during-ramadan-a-randomized-controlled-trial-in-jordanian-men
#11
Mo'ath F Bataineh, Ali M Al-Nawaiseh, Mohammad H Abu Altaieb, David M Bellar, Omar S Hindawi, Lawrence W Judge
Mouth rinsing using a carbohydrate (CHO) solution has been suggested to improve physical performance in fasting participants. This study examined the effects of CHO mouth rinsing during Ramadan fasting on running time to exhaustion and on peak treadmill speed (Vpeak). In a counterbalanced crossover design, 18 sub-elite male runners (Age: 21 ± 2 years, Weight: 68.1 ± 5.7 kg, VO2max: 55.4 ± 4.8 ml/kg/min) who observed Ramadan completed a familiarization trial and three experimental trials. The three trials included rinsing and expectorating a 25 mL bolus of either a 7...
January 24, 2018: European Journal of Sport Science
https://www.readbyqxmd.com/read/29356733/cardiopulmonary-aerobic-fitness-assessment-during-maximal-and-submaximal-exercise-testing-in-pediatric-oncology-patients-after-chemotherapy
#12
Adam W Powell, Rajaram Nagarajan, Wayne A Mays, Clifford Chin, Timothy K Knilans, Sandra K Knecht, Michelle A Amos, Yvette M Gerdes, Thomas D Ryan
PURPOSE: The cardiopulmonary exercise test (CPET) is a valuable tool to assess cardiopulmonary exercise capacity in pediatric oncology patients after chemotherapy. In addition, few studies on the utility of submaximal testing have been performed, which could be important as some patients are unable to complete a maximal effort test secondary to deconditioning by both disease and treatment. MATERIALS AND METHODS: We performed a retrospective chart review of pediatric cancer patients exposed to chemotherapy from 1992 to 2013 who underwent CPET with cycle ergometry (n=27)...
January 19, 2018: American Journal of Clinical Oncology
https://www.readbyqxmd.com/read/29351160/acute-cardiorespiratory-and-metabolic-effects-of-a-sandbag-resistance-exercise-protocol
#13
Nicholas A Ratamess, Jie Kang, Jeremy D Kuper, Elizabeth A O'Grady, Nicole L Ellis, Ira T Vought, Emma Culleton, Jill A Bush, Avery D Faigenbaum
The purpose of the present study was to examine the acute cardiorespiratory and metabolic effects of a sandbag (SB) resistance exercise protocol and compare the responses to time-matched treadmill running protocols. Eight healthy, resistance-trained men (21.1 ± 1.0 years; 86.1 ± 7.8 kg) completed four protocols of equal duration in random sequence: 1) SB, 2) treadmill running at 60% of VO2 reserve (60VO2R), 3) treadmill running at 80% of VO2 reserve (80VO2R), and 4) a control protocol. The SB protocol was 16 min in duration and consisted of 3 circuits of 8 multiple-joint exercises (with 11-, 20-, or -48 kg sandbags) performed for as many repetitions as possible for 20 sec followed by a 10-sec rest interval prior to beginning the next exercise...
January 17, 2018: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/29324580/relationship-between-skating-economy-and-performance-during-a-repeated-shift-test-in-elite-and-subelite-ice-hockey-players
#14
Nicholas R Lamoureux, Grant R Tomkinson, Benjamin J Peterson, John S Fitzgerald
Lamoureux, NR, Tomkinson, GR, Peterson, BJ, and Fitzgerald, JS. Relationship between skating economy and performance during a repeated-shift test in elite and subelite ice hockey players. J Strength Cond Res 32(4): 1109-1113, 2018-The purpose of this study was to determine the importance of skating economy to fatigue during repeated high-intensity efforts of a simulated ice hockey shift. Forty-five collegiate and Junior A male ice hockey players (aged 18-24 years) performed a continuous graded exercise test using a skate treadmill...
April 2018: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/29239992/comparison-of-resistance-based-walking-cardiorespiratory-test-to-the-bruce-protocol
#15
Christopher P Hurt, Marcas Bamman, Avantika Naidu, David A Brown
Cardiorespiratory fitness is assessed through graded exercise tests that determine the maximum amount of sustained mechanical work that an individual can perform while also providing health and fitness related information. This manuscript describes a novel method to perform graded exercise tests that uses posteriorly directed resistive forces. The purpose of this investigation is to validate a novel resistance based test in comparison to a traditional speed and incline based test in a cohort of non-impaired individuals...
December 11, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/29191982/case-studies-in-physiology-exercise-induced-diaphragm-fatigue-in-a-paralympic-champion-rower-with-spinal-cord-injury
#16
Nicholas B Tiller, Thomas R Aggar, Christopher R West, Lee M Romer
INTRODUCTION: The aim of this case report was to determine whether maximal upper-body exercise was sufficient to induce diaphragm fatigue in a Paralympic champion adaptive rower with low-lesion spinal cord injury (SCI). CASE PRESENTATION: An elite arms-only oarsman (age 28 y, stature 1.89 m, mass 90.4 kg) with motor-complete SCI (T12 ) performed a 1000 m time-trial on an adapted rowing ergometer. Exercise measurements comprised pulmonary ventilation and gas exchange, diaphragm EMG-derived indices of neural respiratory drive and intrathoracic pressure-derived indices of respiratory mechanics...
November 30, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29149469/cuffed-versus-uncuffed-endotracheal-tubes-for-general-anaesthesia-in-children-aged-eight-years-and-under
#17
REVIEW
Flavia A De Orange, Rebeca Gac Andrade, Andrea Lemos, Paulo Sgn Borges, José N Figueiroa, Pete G Kovatsis
BACKGROUND: Since the introduction of endotracheal intubation in paediatrics, uncuffed endotracheal tubes (ETTs) have been the standard of care for children under eight years old, based on the presumption that complications, particularly postoperative stridor, are higher with cuffed ETTs. The major disadvantages of uncuffed ETTs cited for this shift in procedure include the difficulty in achieving tidal volumes due to leakage around an uncuffed ETT. To seal the airway adequately, uncuffed tubes may need to be exchanged for another tube with a larger diameter, which sometimes requires several attempts before the appropriate size is found...
November 17, 2017: Cochrane Database of Systematic Reviews
https://www.readbyqxmd.com/read/29148627/assessment-of-endpoint-criteria-and-perceived-barriers-during-maximal-cardiorespiratory-fitness-testing-among-pregnant-women
#18
Caitlin M Hesse, Rachel A Tinius, Bailey J Cooley, Alyssa A Olenick, Maire M Blankenship, Donald L Hoover, Jill M Maples
BACKGROUND: A plateau in volume of oxygen consumption (VO2) is the primary indicator for determining if an individual has reached their maximal aerobic capacity. However, secondary criteria can also be used to identify maximal effort (i.e. lactate level, rating of perceived exertion (RPE), percent of age-predicted maximal heart rate (HR) and respiratory exchange ratio (RER)). Age and gender-specific secondary criteria have been developed for the general population, but no secondary criteria have been established for pregnant women...
November 17, 2017: Journal of Sports Medicine and Physical Fitness
https://www.readbyqxmd.com/read/29135398/the-effect-of-obesity-on-dyspnea-exercise-capacity-walk-work-and-workload-in-patients-with-copd
#19
Hülya Şahin, İlknur Naz, Yelda Varol, Berna Kömürcüoğlu
Introduction: COPD and obesity are major public health problems that cause mortality and morbidity all over the world. The combined of COPD and obesity is predicted to increase further in the coming years. Obesity primarily affects the pulmonary system by altering respiratory functions, exercise capacity, pulmonary gas exchange, and endurance and power of respiratory muscles. In this study, we aimed to compare the dyspnea sensation, exercise capacity, walk work and workload in obese COPD patients compared to preobese and normal overweight COPD patients...
September 2017: Tüberküloz Ve Toraks
https://www.readbyqxmd.com/read/29123389/alveolar-capillary-reserve-during-exercise-in-patients-with-chronic-obstructive-pulmonary-disease
#20
Mehrdad Behnia, Courtney M Wheatley, Alberto Avolio, Bruce D Johnson
Background: Factors limiting exercise in patients with COPD are complex. With evidence for accelerated pulmonary vascular aging, destruction of alveolar-capillary bed, and hypoxic pulmonary vasoconstriction, the ability to functionally expand surface area during exercise may become a primary limitation. Purpose: To quantify measures of alveolar-capillary recruitment during exercise and the relationship to exercise capacity in a cohort of COPD patients. Methods: Thirty-two subjects gave consent (53% male, with mean ± standard deviation age 66±9 years, smoking 35±29 pack-years, and Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification of 0-4: 2...
2017: International Journal of Chronic Obstructive Pulmonary Disease
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