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Frontiers in Skeletal Muscle Wasting, Regeneration and Stem Cells

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889198320 Year: Pages: 259 DOI: 10.3389/978-2-88919-832-0 Language: English
Publisher: Frontiers Media SA
Subject: Physiology --- Science (General)
Added to DOAB on : 2016-01-19 14:05:46
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The search for knowledge on cellular and molecular mechanisms involved in skeletal muscle mass homeostasis and regeneration is an exciting scientific area and extremely important to develop therapeutic strategies for neuromuscular disorders and conditions related to muscle wasting. The mechanisms involved in the regulation of skeletal muscle mass and regeneration consist of molecular signaling pathways modulating protein synthesis and degradation, bioenergetics alterations and preserved function of muscle stem cells. In the last years, different kinds of stem cells has been reported to be localized into skeletal muscle (satellite cells, mesoangioblasts, progenitor interstitial cells and others) or migrate from non-muscle sites, such as bone marrow, to muscle tissue in response to injury. In addition, myogenic progenitor cells are also activated in skeletal muscle wasting disorders. The goal of this research topic is to highlight the available knowledge regarding skeletal muscle and stem cell biology in the context of both physiological and pathological conditions. Our purpose herein is to facilitate better dissemination of research into skeletal muscle physiology field.

Myofilament Function in Health and Disease

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451869 Year: Pages: 161 DOI: 10.3389/978-2-88945-186-9 Language: English
Publisher: Frontiers Media SA
Subject: Physiology --- Science (General)
Added to DOAB on : 2017-08-28 14:01:09
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The present E-book, consisting of a compilation of original articles and reviews, presents how myofilaments are regulated in cardiac and skeletal muscles and trigger contraction. Additionally, this E-book gives insights into their dysregulation in a number of muscle disorders.

Keywords

Contraction --- Muscle --- Heart --- skeletal muscle --- sarcomere --- Myosin --- Actin --- Myopathy

Dietary Protein and Muscle in Aging People

Authors: ---
ISBN: 9783038974574 / 9783038974581 Year: Pages: 160 DOI: 10.3390/books978-3-03897-458-1 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Nutrition and Food Sciences
Added to DOAB on : 2019-02-14 10:56:39
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This Special Issue of Nutrients, entitled “Dietary Proteins and Muscle in Aging People”, welcomes the submission of manuscripts either reporting original research or reviewing the scientific literature. Manuscripts should focus on the mechanisms linking dietary protein with muscle quality and quantity. Articles presenting results from clinical trials testing protein interventions on muscle mass and function are welcome. The Special Issue aims at including articles spanning different disciplines to explore the topic of interest. Reports from basic to clinical and population research are suitable. Articles adopting a longitudinal approach or reporting data from life-long interventions/observations in the exploration of the theme will be given special consideration.Potential topics include, but are not limited to:•Description of patterns of dietary protein consumption across life•Influence of dietary protein intake on the functional status of older people•Preclinical and clinical studies describing the mechanisms through which protein intake modifies muscle mass and function•Protein/amino acid supplementation interventions against sarcopenia, cachexia, or disease conditions associated with muscle wasting in old age•Disease-specific alterations modifying the effects of dietary protein intake on skeletal muscles•Effects of the interactions of dietary protein intake and gut microbiota on skeletal muscles]

Mitochondria in Skeletal Muscle Health, Aging and Diseases

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889450732 Year: Pages: 142 DOI: 10.3389/978-2-88945-073-2 Language: English
Publisher: Frontiers Media SA
Subject: Physiology --- Science (General)
Added to DOAB on : 2017-07-06 13:27:36
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Skeletal muscle is the most abudant tissue of the human body, making up to 40 to 50% of the human body mass. While the importance of optimal muscle function is well recognized in the athletic field, its significance for general health is often underappreciated. In fact, the evidence that muscle mass, strength and metabolism are essential for our overall health is overwhelming. As the largest protein reservoir in the human body, muscles are essential in the acute response to critical illness such as sepsis, advanced cancer, and traumatic injury. Loss of skeletal muscle mass has also been associated with weakness, fatigue, insulin resistance, falls, fractures, frailty, disability, several chronic diseases and death. As a consequence, maintaining skeletal muscle mass, strength and metabolism throughout the lifespan is critical to the maintenance of whole body health. Mitochondria are fascinating organelles regulating many critical cellular processes for skeletal muscle physiology, including for instance energy supply, reactive oxygen species production, calcium homeostasis and the regulation of apoptosis. It is therefore not surprising that mitochondrial dysfunction has been implicated in a large number of adverse events/conditions and pathologies affecting skeletal muscle health. While the importance of normal mitochondrial function is well recognized for muscle physiology, there are important aspects of mitochondrial biology that are still poorly understood. These include mitochondrial dynamics (fusion and fission processes), morphology and processes involved in mitochondrial quality control (mitophagy). Defining the mechanisms regulating these different aspects of mitochondrial biology, their importance for muscle physiology, as well as the interrelations will be critical for expanding understanding of the role played by mitochondria in skeletal muscle physiology and health. The present research topic provides readers with novel experimental approaches, knowledge, hypotheses and findings related to all aspects of mitochondrial biology in healthy and diseased muscle cells.Skeletal muscle is the most abudant tissue of the human body, making up to 40 to 50% of the human body mass. While the importance of optimal muscle function is well recognized in the athletic field, its significance for general health is often underappreciated. In fact, the evidence that muscle mass, strength and metabolism are essential for our overall health is overwhelming. As the largest protein reservoir in the human body, muscles are essential in the acute response to critical illness such as sepsis, advanced cancer, and traumatic injury. Loss of skeletal muscle mass has also been associated with weakness, fatigue, insulin resistance, falls, fractures, frailty, disability, several chronic diseases and death. As a consequence, maintaining skeletal muscle mass, strength and metabolism throughout the lifespan is critical to the maintenance of whole body health. Mitochondria are fascinating organelles regulating many critical cellular processes for skeletal muscle physiology, including for instance energy supply, reactive oxygen species production, calcium homeostasis and the regulation of apoptosis. It is therefore not surprising that mitochondrial dysfunction has been implicated in a large number of adverse events/conditions and pathologies affecting skeletal muscle health. While the importance of normal mitochondrial function is well recognized for muscle physiology, there are important aspects of mitochondrial biology that are still poorly understood. These include mitochondrial dynamics (fusion and fission processes), morphology and processes involved in mitochondrial quality control (mitophagy). Defining the mechanisms regulating these different aspects of mitochondrial biology, their importance for muscle physiology, as well as the interrelations will be critical for expanding understanding of the role played by mitochondria in skeletal muscle physiology and health. The present research topic provides readers with novel experimental approaches, knowledge, hypotheses and findings related to all aspects of mitochondrial biology in healthy and diseased muscle cells.

Redox Regulation in Skeletal Muscle Aging and Exercise

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451968 Year: Pages: 101 DOI: 10.3389/978-2-88945-196-8 Language: English
Publisher: Frontiers Media SA
Subject: Physiology --- Science (General)
Added to DOAB on : 2017-10-13 14:57:01
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Skeletal muscle represents the largest organ of the human body and comprises about 40% of total body mass in humans. Even in people who ‘age well’, there is a noticeable loss of muscle strength and function that accelerates dramatically after the age of 60, a major factor in the reduction in life quality for the aging population. One of the most effective interventions to maintain muscle mass and function is through exercise. Skeletal muscle generates reactive oxygen and reactive nitrogen (ROS/RNS) species in response to muscle contractions. The concentration and species of ROS/RNS generated can depend on the age and fitness of the individual, muscle fibre type and the intensity of the muscle contractions. ROS/RNS generate unique signaling cascades that are not only essential in skeletal muscle contraction and adaptation but also play a role in a wide array of cell processes including cell proliferation, protein synthesis/degradation, immune response and antioxidant defense. ROS/RNS generated by contractions are involved in a co-ordinated local response that is tightly controlled at all levels from generation to detoxification. This collection of original articles and reviews highlights investigations that measure different aspects of the redox response of skeletal muscle to aging and exercise.

From Brain to Body: The Impact of Nervous System Declines on Muscle Performance in Aging

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196869 Year: Pages: 154 DOI: 10.3389/978-2-88919-686-9 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
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The deterioration of skeletal muscle performance (e.g., declines in muscle strength and motor performance) with advancing age has long been anecdotally recognized as Shakespeare pointed out nearly a half millennium ago in his monologue The Seven Ages of Man, and has been of scientific interest for well over a century. Over the past several decades the scientific and medical communities have recognized that reduced skeletal muscle performance is a debilitating and life threatening condition in the elderly. For example, the age-associated loss of muscle strength, as well as impairment in the ability to finely control movement, is highly associated with physical disability and difficulty performing activities of daily living. While the nervous system is widely recognized for its role in controlling skeletal muscle during motor function, its role in determining the performance characteristics of aged skeletal muscle has largely been understudied. Historically, it was believed that these reductions in muscle performance were primarily resultant of age-associated adaptations in skeletal muscle (e.g., muscle atrophy). However, aging is associated with widespread qualitative and quantitative changes in both the central and peripheral nervous systems that are likely to influence numerous aspects of muscle performance, such as muscle strength, fatigue, and motor control, as well as mobility. In this research topic, we sought to examine a broad range of issues surrounding: 1) the age-related changes in nervous system anatomical, physiological, and biochemical changes in the central and/or peripheral nervous systems; 2) the functional role of these nervous system changes in contributing to altered skeletal muscle performance and/or mobility; and 3) physical and pharmacologic interventions that act via the nervous system to enhance muscle performance and/or mobility. Researchers and academicians engaged in aging, neuroscience, and/or applied physiology research focused within the scope of this research topic, were encouraged to contribute an original research article, review article, clinical case study, hypothesis and theory article, method article, opinion article, or technology report to this research topic. Herein, we present a series of outstanding articles within this scope of work, including a last minute addition article from Wiesmeier, Dalin and Maurer that is not mentioned in the editorial, that we hope will help to vertically advance the intersecting fields of aging/geriatrics and neuroscience. Lastly, as the editors, we wish to thank all article contributors and peer reviewers for their efforts in contributing to this Research Topic journal issue/book. Additionally, we would like to thank people everywhere who volunteer their time and body for human subjects research studies, such that are presented herein. It is the wonderful individuals who are willing to participate in experiments that make scientific exploration and health and medical advancements possible.

Keywords

Muscle --- Sarcopenia --- dynapenia --- Aging --- Frailty --- weakness --- motor control

Regulation of Endurance Performance: New Frontiers

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453290 Year: Pages: 246 DOI: 10.3389/978-2-88945-329-0 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Physiology
Added to DOAB on : 2018-02-27 16:16:45
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Successful endurance performance requires the integration of multiple physiological and psychological systems, working together to regulate exercise intensity in a way that will reduce time taken or increase work done. The systems that ultimately limit performance of the task are hotly contested, and may depend on a variety of factors including the type of task, the environment, external influences, training status of the individual and a host of psychological constructs. These factors can be studied in isolation, or inclusively as a whole-body or integrative system. A reductionist approach has traditionally been favoured, leading to a greater understanding and emphasis on muscle and cardiovascular physiology, but the role of the brain and how this integrates multiple systems is gaining momentum. However, these differing approaches may have led to false dichotomy, and now with better understanding of both fields, there is a need to bring these perspectives together. The divergent viewpoints of the limitations to human performance may have partly arisen because of the different exercise models studied. These can broadly be defined as open loop (where a fixed intensity is maintained until task disengagement), or closed loop (where a fixed distance is completed in the fastest time), which may involve whole-body or single-limb exercise. Closed loop exercise allows an analysis of how exercise intensity is self-regulated (i.e. pacing), and thus may better reflect the demands of competitive endurance performance. However, whilst this model can monitor changes in pacing, this is often at the expense of detecting subtle differences in the measured physiological or psychological variables of interest. Open loop exercise solves this issue, but is limited by its more restrictive exercise model. Nonetheless, much can be learnt from both experimental approaches when these constraints are recognised. Indeed, both models appear equally effective in examining changes in performance, and so the researcher should select the exercise model which can most appropriately test the study hypothesis. Given that a multitude of both internal (e.g. muscle fatigue, perception of effort, dietary intervention, pain etc.) and external (e.g. opponents, crowd presence, course topography, extrinsic reward etc.) factors likely contribute to exercise regulation and endurance performance, it may be that both models are required to gain a comprehensive understanding. Consequently, this research topic seeks to bring together papers on endurance performance from a variety of paradigms and exercise models, with the overarching aim of comparing, examining and integrating their findings to better understand how exercise is regulated and how this may (or may not) limit performance.

Keywords

Pacing --- Performance --- Fatigue --- Exercise --- Brain --- Muscle --- Running --- Cycling --- Triathlon --- Training

Pathophysiological Mechanisms of Sarcopenia in Aging and in Muscular Dystrophy: A Translational Approach

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196845 Year: Pages: 248 DOI: 10.3389/978-2-88919-684-5 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
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Loss of muscle mass and increased fibrosis characterize both sarcopenia of aging and muscular dystrophy. Research is increasingly showing that these two conditions also share several pathophysiological mechanisms, including mitochondrial dysfunction, increased apoptosis, abnormal modulation of autophagy, decline in satellite cells, increased generation of reactive oxygen species, and abnormal regulation of signaling and stress response pathways. This Research Topic will cover several mechanisms involved in aging and dystrophic sarcopenia and explore the therapeutic potential of various strategies for intervention.

Hormones, Metabolism and the Benefits of Exercise

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Book Series: Research and Perspectives in Endocrine Interactions ISSN: 1861-2253 ISBN: 9783319727899 9783319727905 Year: Pages: 102 DOI: https://doi.org/10.1007/978-3-319-72790-5 Language: English
Publisher: Springer Grant: Fondation Ipsen
Subject: Internal medicine
Added to DOAB on : 2018-06-29 10:36:57
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The world is faced with an epidemic of metabolic diseases such as obesity and type 2 diabetes. This is due to changes in dietary habits and the decrease in physical activity. Exercise is usually part of the prescription, the first line of defense, to prevent or treat metabolic disorders. However, we are still learning how and why exercise provides metabolic benefits in human health. This open access volume focuses on the cellular and molecular pathways that link exercise, muscle biology, hormones and metabolism. This will include novel “myokines” that might act as new therapeutic agents in the future.

High-Intensity Exercise in Hypoxia - Beneficial Aspects and Potential Drawbacks

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889454068 Year: Pages: 169 DOI: 10.3389/978-2-88945-406-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Physiology
Added to DOAB on : 2018-11-16 17:17:57
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In the past, ‘traditional’ moderate-intensity continuous training (60-75% peak heart rate) was the type of physical activity most frequently recommended for both athletes and clinical populations (cf. American College of Sports Medicine guidelines). However, growing evidence indicates that high-intensity interval training (80-100% peak heart rate) could actually be associated with larger cardiorespiratory fitness and metabolic function benefits and, thereby, physical performance gains for athletes. Similarly, recent data in obese and hypertensive individuals indicate that various mechanisms – further improvement in endothelial function, reductions in sympathetic neural activity, or in arterial stiffness – might be involved in the larger cardiovascular protective effects associated with training at high exercise intensities. Concerning hypoxic training, similar trends have been observed from ‘traditional’ prolonged altitude sojourns (‘Live High Train High’ or ‘Live High Train Low’), which result in increased hemoglobin mass and blood carrying capacity. Recent innovative ‘Live Low Train High’ methods (‘Resistance Training in Hypoxia’ or ‘Repeated Sprint Training in Hypoxia’) have resulted in peripheral adaptations, such as hypertrophy or delay in muscle fatigue. Other interventions inducing peripheral hypoxia, such as vascular occlusion during endurance/resistance training or remote ischemic preconditioning (i.e. succession of ischemia/reperfusion episodes), have been proposed as methods for improving subsequent exercise performance or altitude tolerance (e.g. reduced severity of acute-mountain sickness symptoms). Postulated mechanisms behind these metabolic, neuro-humoral, hemodynamics, and systemic adaptations include stimulation of nitric oxide synthase, increase in anti-oxidant enzymes, and down-regulation of pro-inflammatory cytokines, although the amount of evidence is not yet significant enough. Improved O2 delivery/utilization conferred by hypoxic training interventions might also be effective in preventing and treating cardiovascular diseases, as well as contributing to improve exercise tolerance and health status of patients. For example, in obese subjects, combining exercise with hypoxic exposure enhances the negative energy balance, which further reduces weight and improves cardio-metabolic health. In hypertensive patients, the larger lowering of blood pressure through the endothelial nitric oxide synthase pathway and the associated compensatory vasodilation is taken to reflect the superiority of exercising in hypoxia compared to normoxia. A hypoxic stimulus, in addition to exercise at high vs. moderate intensity, has the potential to further ameliorate various aspects of the vascular function, as observed in healthy populations. This may have clinical implications for the reduction of cardiovascular risks. Key open questions are therefore of interest for patients suffering from chronic vascular or cellular hypoxia (e.g. work-rest or ischemia/reperfusion intermittent pattern; exercise intensity; hypoxic severity and exposure duration; type of hypoxia (normobaric vs. hypobaric); health risks; magnitude and maintenance of the benefits). Outside any potential beneficial effects of exercising in O2-deprived environments, there may also be long-term adverse consequences of chronic intermittent severe hypoxia. Sleep apnea syndrome, for instance, leads to oxidative stress and the production of reactive oxygen species, and ultimately systemic inflammation. Postulated pathophysiological changes associated with intermittent hypoxic exposure include alteration in baroreflex activity, increase in pulmonary arterial pressure and hematocrit, changes in heart structure and function, and an alteration in endothelial-dependent vasodilation in cerebral and muscular arteries. There is a need to explore the combination of exercising in hypoxia and association of hypertension, developmental defects, neuro-pathological and neuro-cognitive deficits, enhanced susceptibility to oxidative injury, and possibly increased myocardial and cerebral infarction in individuals sensitive to hypoxic stress. The aim of this Research Topic is to shed more light on the transcriptional, vascular, hemodynamics, neuro-humoral, and systemic consequences of training at high intensities under various hypoxic conditions.

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