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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
Tatsuro Amano, Seiko Kai, Michi Nakajima, Tomoko Ichinose-Kuwahara, Nicola Gerrett, Narihiko Kondo, Yoshimitsu Inoue
The purpose of the present study is to investigate sweating responses to isometric handgrip (IH) exercise and muscle metaboreflex in prepubertal children and the elderly. In hot condition (ambient temperature, 35°C; relative humidity, 45%), 13 healthy young adults, 10 prepubertal children, and 10 elderly (age: 20.4±1.2, 11.4±0.5, and 63.5±3.1 years, respectively) repeated three handgrip-exercise protocol that consisted of 1 min IH exercise at 15, 30, or 45% of maximum voluntary contractions (MVC) followed by 2 min post-exercise forearm occlusion...
November 11, 2016: Experimental Physiology
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
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 is, in part, a function of muscle metaboreflex activation (MMA). As SNA is heightened even at rest in subjects with hypertension (HTN), we tested whether HTN causes exaggerated coronary vasoconstriction during mild treadmill exercise with MMA (elicited by reducing hindlimb blood flow by ~60%) thereby limiting increases in CBF and ventricular performance...
October 21, 2016: American Journal of Physiology. Heart and Circulatory Physiology
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 S 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)...
November 1, 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 haemodynamics 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...
December 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 Junior, Andrea Pio de Abreu, Giovanio Vieira da Silva, Décio Mion-Junior, Cláudia Lúcia de Moraes Forjaz
KEY POINTS: Recent evidence indicates that metaboreflex regulates heart rate recovery after exercise (HRR). An increased metaboreflex activity during the post-exercise period might help to explain the reduced HRR observed in hypertensive subjects. Using lower limb circulatory occlusion, the present study showed that metaboreflex activation during the post-exercise period delayed HRR in never-treated hypertensive men compared to normotensives. These findings may be relevant for understanding the physiological mechanisms associated with autonomic dysfunction in hypertensive men...
November 1, 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
KEY POINTS: Recent evidence indicates a role for group III/IV muscle afferents in reflex control of the human ventilatory response to exercise. Dyspnoea in chronic obstructive pulmonary disease (COPD) may be linked to this reflex response. This study shows that activation of the muscle metaboreflex causes a ventilatory response in COPD patients but not in healthy controls. This indicates abnormal involvement of muscle afferents in the control of ventilation in COPD which may be a contributing factor to exercise dyspnoea...
October 15, 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
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