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Jasdeep Kaur, Alberto Alvarez, Hanna W Hanna, Abhinav C Krishnan, Danielle Senador, Tiago M Machado, Yasir H Altamimi, Abe T Lovelace, Maryetta D Dombrowski, Marty D Spranger, Donal O'Leary
The muscle metaboreflex and arterial baroreflex regulate arterial pressure through distinct mechanisms. During submaximal exercise muscle metaboreflex activation (MMA) elicits a pressor response virtually solely by increasing cardiac output (CO) while baroreceptor unloading increases mean arterial pressure (MAP) primarily through peripheral vasoconstriction. The interaction between the two reflexes when activated simultaneously has not been well established. We activated the muscle metaboreflex in chronically instrumented canines during dynamic exercise (via graded reductions in hindlimb blood flow; HLBF) followed by simultaneous baroreceptor unloading (via bilateral carotid occlusion; BCO)...
September 9, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Arturo Figueroa, Stacey Alvarez-Alvarado, Salvador J Jaime, Sarah A Johnson, Jeremiah C Campbell, Rafaela G Feresin, Marcus L Elam, Negin Navaei, Shirin Pourafshar, Bahram H Arjmandi
Sarcopenia, defined by reduced appendicular skeletal muscle mass (ASM)/height(2) (ASMI), is associated with increased arterial stiffness (brachial-ankle pulse wave velocity, baPWV) and wave reflection (augmentation index, AIx). Blood pressure (BP) responses to metaboreflex activation (post-exercise muscle ischemia, PEMI) are exaggerated in older prehypertensives and hypertensives. We examined peripheral and aortic hemodynamics at rest and during PEMI in postmenopausal women with low-ASMI and normal-ASMI. Resting radial AIx and baPWV as well as brachial and aortic systolic BP, pulse pressure, systolic time index, and subendocardial viability ratio (SEVR) responses to PEMI were greater in women with low-ASMI than normal-ASMI...
August 25, 2016: Clinical and Experimental Pharmacology & Physiology
Joshua R Smith, Ryan M Broxterman, Shane M Hammer, Andrew M Alexander, Kaylin D Didier, Stephanie P Kurti, Thomas J Barstow, Craig A Harms
It is currently unknown whether sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. We hypothesized that the activation of the inspiratory muscle metaboreflex will lead to less of an increase in mean arterial pressure (MAP) and limb vascular resistance (LVR) and less of a decrease in limb blood flow (Q̇L) in women compared with men. Twenty healthy men (n = 10, 23 ± 2 yr) and women (n = 10, 22 ± 3 yr) were recruited for this study. Subjects performed inspiratory resistive breathing tasks (IRBTs) at 2% or 65% of their maximal inspiratory mouth pressure (PIMAX)...
September 1, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Simone Regina Posser, Carine Cristina Callegaro, Marina Beltrami-Moreira, Leila Beltrami Moreira
BACKGROUND: Hypertension is a complex chronic condition characterized by elevated arterial blood pressure. Management of hypertension includes non-pharmacologic strategies, which may include techniques that effectively reduce autonomic sympathetic activity. Respiratory exercises improve autonomic control over cardiovascular system and attenuate muscle metaboreflex. Because of these effects, respiratory exercises may be useful to lower blood pressure in subjects with hypertension. METHODS/DESIGN: This randomized, double-blind clinical trial will test the efficacy of inspiratory muscle training in reducing blood pressure in adults with essential hypertension...
2016: Trials
Eliza Prodel, James P Fisher, Thales C Barbosa, Igor A Fernandes, Antonio C Nobrega, Lauro C Vianna
BACKGROUND: Heightened aortic augmentation index (AIx; surrogate of arterial stiffness) is associated with an elevated risk of cardiovascular events; however, it is currently unclear whether peripheral blood pressure (BP) modulates AIx. AIM: Given this, we studied the relationship between AIx and BP under resting conditions as well as during skeletal muscle metaboreflex activation, which is a maneuver that generates steady elevations in BP. METHODS: In nine healthy male participants (23±2 years), the graded activation of the muscle metaboreflex was achieved by postexercise ischemia (PEI) following moderate and high-intensity static handgrip performed at 30 and 40% maximum voluntary contraction...
October 2016: Blood Pressure Monitoring
Tiago Peçanha, Leandro Campos de Brito, Rafael Yokoyama Fecchio, Patricia Nascimento de Sousa, Natan Daniel da Silva-Júnior, Andrea Pio de Abreu, Giovanio Vieira da Silva, Décio Mion-Junior, Cláudia Lúcia de Moraes Forjaz
Muscle metaboreflex influences heart rate (HR) regulation after aerobic exercise. Therefore, increased metaboreflex sensitivity may help to explain the delayed HR recovery (HRR) reported in hypertension. This study assessed and compared the effect of metaboreflex activation after exercise on HRR, cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV) in normotensive (NT) and hypertensive (HT) men. Twenty-three never-treated HT and 25 NT men randomly underwent two-cycle ergometer exercise sessions (30min, 70%VO2peak ) followed by 5 min of inactive recovery performed with (occlusion) or without (control) leg circulatory occlusion (calf cuff inflated to a suprasystolic pressure)...
July 20, 2016: Journal of Physiology
Joshua R Smith, Ryan M Broxterman, Shane M Hammer, Andrew M Alexander, Kaylin D Didier, Thomas J Barstow, Stephanie P Kurti, Craig A Harms
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Antonio Crisafulli, Silvana Roberto, Girolamo Palazzolo, Irene Sanna, Gianmarco Sainas, Matteo Pusceddu, Gabriele Mulliri, Raffaele Milia
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Sara Magnani, Filippo Tocco, Giovanna Ghiani, Elisabetta Marongiu, Gianamrco Sainas, Antonio Crisafulli
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Masaki Mizuno, Scott Crawford, Samuel Rosengarden, Jere H Mitchell, Scott A Smith, Wanpen Vongpatanasin
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Danielle Christine Bentley, Scott Gordon Thomas
Handgrip (HG) exercise has been prescribed as a lifestyle intervention to successfully reduce resting blood pressure (BP) among heterogeneous groups of participants. Current HG protocols have limited accessibility due to complicated exercise prescriptions and sophisticated required equipment. Therefore, this research describes the design and evaluation of the maximal intermittent (MINT) HG exercise strategy, consisting of both a novel exercise protocol (32×5 seconds maximal grip squeezes separated by 5 seconds of rest between sets) and an original grip tool...
2016: Clinical Interventions in Aging
Yuka Itoh, Keisho Katayama, Erika Iwamoto, Kazushige Goto, Yasuhiro Suzuki, Toshiyuki Ohya, Kenji Takao, Koji Ishida
UNLABELLED: The purpose of this study was to elucidate the cardiovascular response during hyperpnoea in endurance-trained runners compared to sedentary controls. Twelve runners and ten sedentary individuals participated in this study. A maximal respiratory endurance test (MRET) was performed as follows: target minute ventilation was initially set at 30% of maximal voluntary ventilation (MVV12) and was increased by 10% MVV12 every 3min. The test was terminated when the subject could no longer maintain the target ventilation...
August 2016: Respiratory Physiology & Neurobiology
Masaki Mizuno, Jere H Mitchell, Scott Crawford, Chou-Long Huang, Naim Maalouf, Ming-Chang Hu, Orson W Moe, Scott A Smith, Wanpen Vongpatanasin
An increasing number of studies have linked high dietary phosphate (Pi) intake to hypertension. It is well established that the rise in sympathetic nerve activity (SNA) and blood pressure (BP) during physical exertion is exaggerated in many forms of hypertension, which are primarily mediated by an overactive skeletal muscle exercise pressor reflex (EPR). However, it remains unknown whether high dietary Pi intake potentiates the EPR-mediated SNA and BP response to exercise. Accordingly, we measured renal SNA (RSNA) and mean BP (MBP) in normotensive Sprague-Dawley rats fed a normal Pi diet (0...
July 1, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Richard M Bruce, Alice Turner, Michael J White
Blockade of thin fibre muscle afferent feedback during dynamic exercise reduces exercise hyperpnoea in health and chronic obstructive pulmonary disease (COPD). Therefore, we hypothesised that activation of the muscle metaboreflex at rest would cause hyperpnoea. To evaluate the effect of muscle metaboreflex activation on ventilation, in resting COPD patients and healthy participants. Following a bout of rhythmic hand grip exercise, post exercise circulatory occlusion (PECO) was applied to the resting forearm to sustain activation of the muscle metaboreflex, in 18 COPD patients (FEV1 /FVC ratio < 70%), 9 also classified as chronically hypercapnic, and 9 age and gender matched controls...
May 12, 2016: Journal of Physiology
Arturo Figueroa, Stacey Alvarez-Alvarado, Salvador J Jaime, Roy Kalfon
Combined isometric exercise or metaboreflex activation (post-exercise muscle ischaemia (PEMI)) and cold pressor test (CPT) increase cardiac afterload, which may lead to adverse cardiovascular events. l-Citrulline supplementation (l-CIT) reduces systemic arterial stiffness (brachial-ankle pulse wave velocity (baPWV)) at rest and aortic haemodynamic responses to CPT. The aim of this study was to determine the effect of l-CIT on aortic haemodynamic and baPWV responses to PEMI+CPT. In all, sixteen healthy, overweight/obese males (age 24 (sem 6) years; BMI 29·3 (sem 4·0) kg/m2) were randomly assigned to placebo or l-CIT (6 g/d) for 14 d in a cross-over design...
July 2016: British Journal of Nutrition
Gabriele Mulliri, Gianmarco Sainas, Sara Magnani, Girolamo Palazzolo, Nicola Milia, Andrea Orrù, Silvana Roberto, Elisabetta Marongiu, Raffaele Milia, Antonio Crisafulli
Ischemic preconditioning (IP) has been shown to improve exercise performance and to delay fatigue. However, the precise mechanisms through which IP operates remain elusive. It has been hypothesized that IP lowers the sensation of fatigue by reducing the discharge of group III and IV nerve endings, which also regulate hemodynamics during the metaboreflex. We hypothesized that IP reduces the blood pressure response during the metaboreflex. Fourteen healthy males (age between 25 and 48 yr) participated in this study...
May 1, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Eliza Prodel, George M Balanos, Igor D Braz, Antonio C L Nobrega, Lauro C Vianna, James P Fisher
We investigated the effect of activating metabolically sensitive skeletal muscle afferents (muscle metaboreflex) on cerebral blood flow and the potentially confounding influence of concomitant changes in the partial pressure of arterial carbon dioxide. Eleven healthy males (25 ± 4 yr) performed submaximal leg cycling exercise on a semirecumbent cycle ergometer (heart rate: ∼120 beats/min), and assessments were made of the partial pressure of end-tidal carbon dioxide (PetCO2 ), internal carotid artery blood flow (ICAQ) and conductance (ICACVC), and middle cerebral artery mean blood velocity (MCAvm) and conductance index (MCACVCi)...
May 1, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Chulee Ubolsakka-Jones, Benjarat Sangthong, Sahachat Aueyingsak, David A Jones
INTRODUCTION: Exercise is generally regarded as beneficial for health, but the consequent increases in blood pressure might pose a risk for hypertensive subjects. The purpose of this study was to determine blood pressure responses to dynamic exercise and sustained handgrip in patients with isolated systolic hypertension (ISH) who were stable on medication. METHODS: Nineteen female ISH patients (66 ± 5 yr) and 19 age-matched normotensive (NT) female controls undertook a 5-min cycle exercise (60% heart rate reserve [HRR]) and a 2-min handgrip exercise (30% maximum voluntary contraction)...
June 2016: Medicine and Science in Sports and Exercise
John P Florian, Friedhelm J Baisch, Martina Heer, James A Pawelczyk
BACKGROUND: Astronauts in space consume fewer calories and return to earth predisposed to orthostatic intolerance. The role that caloric deficit plays in the modulation of autonomic control of the cardiovascular system is unknown. Therefore, the purpose of this study was to determine the effects of 6° head-down bedrest (an analog of spaceflight) with a hypocaloric diet (25 % caloric restriction) (CR) on autonomic neural control during static handgrip (HG) and cold pressor (CP) tests...
2016: Extreme Physiology & Medicine
Jasdeep Kaur, Tiago M Machado, Alberto Alvarez, Abhinav C Krishnan, Hanna W Hanna, Yasir H Altamimi, Danielle Senador, Marty D Spranger, Donal S O'Leary
Metabolite accumulation due to ischemia of active skeletal muscle stimulates group III/IV chemosensitive afferents eliciting reflex increases in arterial blood pressure and sympathetic activity, termed the muscle metaboreflex. We and others have previously demonstrated sympathetically mediated vasoconstriction of coronary, renal, and forelimb vasculatures with muscle metaboreflex activation (MMA). Whether MMA elicits vasoconstriction of the ischemic muscle from which it originates is unknown. We hypothesized that the vasodilation in active skeletal muscle with imposed ischemia becomes progressively restrained by the increasing sympathetic vasoconstriction during MMA...
December 15, 2015: American Journal of Physiology. Heart and Circulatory Physiology
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