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https://www.readbyqxmd.com/read/28646592/influence-of-inspiratory-resistive-loading-on-expiratory-muscle-fatigue-in-healthy-humans
#1
Carli M Peters, Joseph F Welch, Paolo B Dominelli, Yannick Molgat-Seon, Lee M Romer, Donald C McKenzie, A William Sheel
Expiratory resistive loading elicits inspiratory as well as expiratory muscle fatigue, suggesting parallel co-activation of the inspiratory muscles during expiration. It is unknown whether the expiratory muscles are similarly co-activated to the point of fatigue during inspiratory resistive loading (IRL). The purpose of this study was to determine whether IRL elicits expiratory as well as inspiratory muscle fatigue. Healthy male subjects (n = 9) underwent isocapnic IRL (60% maximal inspiratory pressure, 15 breaths∙min(-1) , 0...
June 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28622081/effects-of-inspiratory-muscle-training-in-professional-women-football-players-a-randomized-sham-controlled-trial
#2
Bruno Archiza, Daniela Kuguimoto Andaku, Flávia Cristina Rossi Caruso, José Carlos Bonjorno, Cláudio Ricardo de Oliveira, Paula Angélica Ricci, André Capaldo do Amaral, Stela Márcia Mattiello, Cleiton Augusto Libardi, Shane A Phillips, Ross Arena, Audrey Borghi-Silva
This study was conducted to determine the effects of inspiratory muscle training (IMT) on respiratory and peripheral muscles oxygenation during a maximal exercise tolerance test and on repeated-sprint ability (RSA) performance in professional women football players. Eighteen athletes were randomly assigned to one of the following groups: SHAM (n = 8) or IMT (n = 10). After a maximal incremental exercise test, all participants performed (on a different day) a time-to-exhaustion (Tlim) test. Peripheral and respiratory muscles oxygenation by near-infrared spectroscopy, breath-by-breath ventilatory and metabolic variables, and blood lactate concentration were measured...
June 16, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28522759/effect-of-cyclooxygenase-inhibition-on-the-inspiratory-muscle-metaboreflex-induced-cardiovascular-consequences-in-men
#3
Joshua R Smith, Kaylin D Didier, Shane M Hammer, Andrew M Alexander, Stephanie P Kurti, Steven W Copp, Thomas J Barstow, Craig A Harms
Inspiratory muscle metaboreflex activation increases mean arterial pressure (MAP) and limb vascular resistance (LVR) and decreases limb blood flow (Q̇L). Cyclooxygenase (COX) inhibition has been found to attenuate limb skeletal muscle metaboreflex-induced increases in muscle sympathetic nerve activity. We hypothesized that compared to placebo (PLA), COX inhibition would attenuate inspiratory muscle metaboreflex-induced 1) increases in MAP and LVR and 2) decreases in Q̇L Seven men (22±1 years) were recruited and orally consumed ibuprofen (IB, 10mg/kg) or PLA 90 min prior to performing the cold pressor test (CPT) for 2 min and inspiratory resistive breathing task (IRBT) for 14...
May 18, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28499979/inspiratory-muscle-training-improves-intercostal-and-forearm-muscle-oxygenation-in-patients-with-chronic-heart-failure-evidence-of-the-origin-of-the-respiratory-metaboreflex
#4
Adalgiza M Moreno, Alessandra C Toledo-Arruda, Jéssica S Lima, Carolina S Duarte, Humberto Vilacortta-Junior, Antonio C L Nóbrega
BACKGROUND: The impact of inspiratory muscle training (IMT) on respiratory and peripheral muscle oxygenation and perfusion during inspiratory muscle fatigue in patients with chronic heart failure has not been established. METHODS AND RESULTS: Twenty-six patients with chronic heart failure were randomly assigned to either 8 weeks of IMT or to a control group. Inspiratory fatigue was induced by a progressive inspiratory resistive loading protocol until there was an inability to sustain inspiratory pressure, when the inspiratory muscle metaboreflex should be activated...
May 9, 2017: Journal of Cardiac Failure
https://www.readbyqxmd.com/read/28490452/role-of-endothelial-nitric-oxide-in-control-of-peripheral-vascular-conductance-during-muscle-metaboreflex-activation
#5
Danielle Senador, Jasdeep Kaur, Alberto Alvarez, Hanna W Hanna, Abhinav C Krishnan, Yasir H Altamimi, Donal S O'Leary
Muscle metaboreflex activation during submaximal dynamic exercise, increases arterial pressure primarily via increases in cardiac output as there is little systemic vasoconstriction. Indeed, in normal animals we have often shown a small, but significant, peripheral vasodilation during metaboreflex activation, which is mediated, at least in part, by release of epinephrine and activation of vascular β2 receptors. We tested whether this vasodilation is in part due to increased release of nitric oxide caused by the rise in cardiac output eliciting endothelium-dependent flow-mediated vasodilation...
May 10, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28477375/oral-l-tyrosine-supplementation-augments-the-vasoconstriction-response-to-whole-body-cooling-in-older-adults
#6
James A Lang, Kevin A Smaller
L-tyrosine is the primary substrate for noradrenaline biosynthesis within sympathetic axon terminals. Under stressful conditions requiring increased catecholamine production, axonal L-tyrosine concentration may limit the full expression of the sympathetic effector response and this may be particularly evident in older adults. We hypothesize that oral L-tyrosine supplementation will increase the sympathetic response to whole-body cooling and muscle metaboreflex activation. In a randomized, double-blind design, eleven young (Y = 24 ± 1 years) and eleven older (O = 68 ± 4 years) participants ingested either 150 mg kg(-1) of L-tyrosine or placebo prior to commencing 30 minutes of whole-body cooling to induce a gradual decline in skin temperature from 34 to 30...
May 5, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28424510/the-effect-of-slow-loaded-breathing-training-on-the-blood-pressure-response-to-handgrip-exercise-in-patients-with-isolated-systolic-hypertension
#7
Chulee Ubolsakka-Jones, Benjarat Sangthong, Wilaiwan Khrisanapant, David A Jones
Isolated systolic hypertension (ISH) is the most common form of hypertension in older people. It is characterized by increased resting systolic blood pressure (sBP) and increased sBP in response to exercise. It has previously been shown that slow breathing training reduces resting sBP, and the objective of the present study was to determine whether it also reduced the blood pressure response to static handgrip exercise. ISH patients aged between 60 and 74 years were randomly divided into a control group (10 subjects, 4 of which were male) that breathed normally and a trained group (10 subjects, 4 of which were male) that trained daily for 8 weeks by slow breathing against an inspiratory resistance of 18 cmH2O...
April 20, 2017: Hypertension Research: Official Journal of the Japanese Society of Hypertension
https://www.readbyqxmd.com/read/28381456/muscle-mechanoreflex-activation-via-passive-calf-stretch-causes-renal-vasoconstriction-in-healthy-humans
#8
Rachel C Drew, Cheryl A Blaha, Michael D Herr, Ruda Cui, Lawrence I Sinoway
Reflex renal vasoconstriction occurs during exercise, and renal vasoconstriction in response to upper-limb muscle mechanoreflex activation has been documented. However, the renal vasoconstrictor response to muscle mechanoreflex activation originating from lower limbs, with and without local metabolite accumulation, has not been assessed. Eleven healthy young subjects (26 ± 1y; 5 men) underwent two trials involving 3-min passive calf muscle stretch (mechanoreflex) during 7.5-min lower-limb circulatory occlusion (CO)...
April 5, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28381455/2015-ludwig-lecture-abnormal-cardiovascular-responses-to-exercise-in-hypertension-contribution-of-neural-factors
#9
Jere Holloway Mitchell
During both dynamic (e.g. endurance) and static (e.g. strength) exercise there are exaggerated cardiovascular responses in hypertension. This includes greater increases in blood pressure, heart rate, and efferent sympathetic nerve activity than in normals. Two of the known neural factors which contribute to this abnormal cardiovascular response are the exercise pressor reflex (EPR) and functional sympatholysis. The EPR originates in contracting skeletal muscle and reflexly increases sympathetic efferent nerve activity to the heart and blood vessels as well as decreases parasympathetic efferent nerve activity to the heart...
April 5, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28324618/thermogelling-chitosan-lactate-hydrogel-improves-functional-recovery-after-a-c2-spinal-cord-hemisection-in-rat
#10
Katarzyna Nawrotek, Tanguy Marqueste, Zofia Modrzejewska, Roman Zarzycki, Agnieszka Rusak, Patrick Decherchi
The present study was designed to provide an appropriate micro-environment for regenerating axotomized neurons and proliferating/migrating cells. Because of its intrinsic permissive properties, biocompatibility and biodegradability, we chose to evaluate the therapeutic effectiveness of a chitosan-based biopolymer. The biomaterial toxicity was measured through in vitro test based on fibroblast cell survival on thermogelling chitosan lactate hydrogel substrate and then polymer was implanted into a C2 hemisection of the rat spinal cord...
March 21, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/28235792/cardiovascular-consequences-of-the-inspiratory-muscle-metaboreflex-effects-of-age-and-sex
#11
Joshua R Smith, Andrew M Alexander, Shane M Hammer, Kaylin D Didier, Stephanie P Kurti, Ryan M Broxterman, Thomas J Barstow, Craig A Harms
We hypothesized that, compared to their younger counterparts, older men and women would exhibit greater 1) increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and 2) decreases in limb blood flow (Q̇L), but 3) no sex differences would be present in older adults. Sixteen young (8 men (YM), 8 women (YW); 18-24 yrs) and older (8 men (OM), 8 women (OW); 60-73 yrs) adults performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths min-1 with a 50% duty cycle...
February 24, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28230704/muscle-metaboreflex-control-of-sympathetic-activity-in-obstructive-sleep-apnea
#12
Linda M Ueno-Pardi, Renan S Guerra, Thiago T Goya, Rosyvaldo F Silva, Elisangela M Gara, Marta F Lima, Thais S Nobre, Maria J N N Alves, Ivani C Trombetta, Geraldo Lorenzi-Filho
PURPOSE: Previous studies report abnormal muscle metaboreflex control of muscle sympathetic nerve activity (MSNA) in obesity, hypertension, and heart failure. We hypothesized that obstructive sleep apnea (OSA) is associated with augmented metaboreflex control of MSNA. METHODS: Thirty-one sedentary individuals with no comorbidities (age = 52 ± 1 yr, body mass index = 28 ± 1 kg·m) without (control, n = 14) and with OSA (n = 17) defined by polysomnography, underwent echocardiography...
July 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28183862/the-mechanisms-underlying-the-muscle-metaboreflex-modulation-of-sweating-and-cutaneous-blood-flow-in-passively-heated-humans
#13
Baies Haqani, Naoto Fujii, Narihiko Kondo, Glen P Kenny
Metaboreceptors can modulate cutaneous blood flow and sweating during heat stress but the mechanisms remain unknown. Fourteen participants (31 ± 13 years) performed 1-min bout of isometric handgrip (IHG) exercise at 60% of their maximal voluntary contraction followed by a 3-min occlusion (OCC), each separated by 10 min, initially under low (LHS, to activate sweating without changes in core temperature) and high (HHS, whole-body heating to a core temperature increase of 1.0°C) heat stress conditions. Cutaneous vascular conductance (CVC) and sweat rate were measured continuously at four forearm skin sites perfused with 1) lactated Ringer's solution (Control), 2) 10 mmol L-NAME [inhibits nitric oxide synthase (NOS)], 3) 10 mmol Ketorolac [inhibits cyclooxygenase (COX)], or 4) 4 mmol theophylline (THEO; inhibits adenosine receptors)...
February 2017: Physiological Reports
https://www.readbyqxmd.com/read/27979984/haemodynamic-response-to-muscle-reflex-is-abnormal-in-patients-with-heart-failure-with-preserved-ejection-fraction
#14
Silvana Roberto, Gabriele Mulliri, Raffaele Milia, Roberto Solinas, Virginia Pinna, Gianmarco Sainas, Massimo F Piepoli, Antonio Crisafulli
The aim of the present investigation was to assess the role of cardiac diastole on the hemodynamic response to metaboreflex activation. We wanted to determine whether patients with diastolic function impairment showed a different hemodynamic response as compared to normal subjects during this reflex. Hemodynamics during the metaboreflex activation obtained by post-exercise muscle ischemia (PEMI) was assessed in 10 patients with diagnosed heart failure with preserved ejection fraction (HFpEF) and in 12 age-matched healthy controls (CTL)...
December 15, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27976405/abnormal-muscle-metaboreflex-control-of-ventilation-in-patients-with-chronic-obstructive-pulmonary-disease-what-mechanisms-should-be-blamed
#15
Liliane Cunha Aranda, Jeann L C Sabino-Carvalho, Talita Miranda-Silva, Marcelle Paula-Ribeiro
No abstract text is available yet for this article.
December 15, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27927625/sympathetic-responsiveness-is-not-increased-in-women-with-a-history-of-hypertensive-pregnancy
#16
Sushant M Ranadive, Ronee E Harvey, Brian D Lahr, Virginia M Miller, Michael J Joyner, Jill N Barnes
Hypertensive pregnancy (HTNP) is a risk factor for future cardiovascular disease. Exaggerated cardiovascular responses to physical stress are also considered an independent marker of cardiovascular disease risk. However, there are limited data regarding the blood pressure (BP) responses to acute stress in women, who have a history of HTNP. Hence, the aim of the study is to compare BP responses to a physical stress in postmenopausal women with a history of HTNP to age- and parity-matched women with a history of normotensive pregnancy (NP)...
January 1, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27895592/effects-of-six-months-training-on-physical-capacity-and-metaboreflex-activity-in-patients-with-multiple-sclerosis
#17
Sara Magnani, Sergio Olla, Massimiliano Pau, Girolamo Palazzolo, Filippo Tocco, Azzurra Doneddu, Maura Marcelli, Andrea Loi, Federica Corona, Francesco Corona, Giancarlo Coghe, Maria G Marrosu, Alberto Concu, Eleonora Cocco, Elisabetta Marongiu, Antonio Crisafulli
Patients with multiple sclerosis (MS) have an increased systemic vascular resistance (SVR) response during the metaboreflex. It has been hypothesized that this is the consequence of a sedentary lifestyle secondary to MS. The purpose of this study was to discover whether a 6-month training program could reverse this hemodynamic dysregulation. Patients were randomly assigned to one of the following two groups: the intervention group (MSIT, n = 11), who followed an adapted training program; and the control group (MSCTL, n = 10), who continued with their sedentary lifestyle...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27859912/sweating-responses-to-isometric-hand-grip-exercise-and-forearm-muscle-metaboreflex-in-prepubertal-children-and-elderly
#18
Tatsuro Amano, Seiko Kai, Michi Nakajima, Tomoko Ichinose-Kuwahara, Nicola Gerrett, Narihiko Kondo, Yoshimitsu Inoue
What is the central question of this study? Non-thermal factors (e.g. muscle metaboreflex) contribute to the sweating response during exercise. Although it is well recognized that the sweating responses caused by core temperature elevation in prepubertal children and the elderly are attenuated compared with young adults, it is unknown whether non-thermal sweating is also attenuated in these populations. What is the main finding and its importance? The non-thermal sweating response during isometric hand-grip exercise and isolated muscle metaboreflex were attenuated in prepubertal children compared with young adults in a non-uniform manner over the body, but only during the muscle metaboreflex in the elderly...
February 1, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/27784689/central-vs-peripheral-determinants-of-sympathetic-neural-recruitment-insights-from-static-handgrip-exercise-and-postexercise-circulatory-occlusion
#19
Mark B Badrov, T Dylan Olver, J Kevin Shoemaker
Sympathetic outflow is modified during acute homeostatic stress through increased firing of low-threshold axons, recruitment of latent axons, and synaptic delay modifications. However, the role of central mechanisms versus peripheral reflex control over sympathetic recruitment remains unknown. Here, we examined sympathetic discharge patterns during fatiguing static handgrip (SHG) exercise and postexercise circulatory occlusion (PECO) to study the central vs. peripheral reflex elements of sympathetic neural coding...
December 1, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27769997/exaggerated-coronary-vasoconstriction-limits-muscle-metaboreflex-induced-increases-in-ventricular-performance-in-hypertension
#20
Marty D Spranger, Jasdeep Kaur, Javier A Sala-Mercado, Abhinav C Krishnan, Rania Abu-Hamdah, Alberto Alvarez, Tiago M Machado, Robert A Augustyniak, Donal S O'Leary
Increases in myocardial oxygen consumption during exercise mainly occur via increases in coronary blood flow (CBF) as cardiac oxygen extraction is high even at rest. However, sympathetic coronary constrictor tone can limit increases in CBF. Increased sympathetic nerve activity (SNA) during exercise likely occurs via the action of and interaction among activation of skeletal muscle afferents, central command, and resetting of the arterial baroreflex. As SNA is heightened even at rest in subjects with hypertension (HTN), we tested whether HTN causes exaggerated coronary vasoconstriction in canines during mild treadmill exercise with muscle metaboreflex activation (MMA; elicited by reducing hindlimb blood flow by ~60%) thereby limiting increases in CBF and ventricular performance...
January 1, 2017: American Journal of Physiology. Heart and Circulatory Physiology
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