The repeated bout effect evokes the training-induced skeletal muscle cellular memory.

Physical exercise is well-established as beneficial for health. With the 20th-century epidemiological transition, promoting healthy habits like exercise has become crucial for preventing chronic diseases. Stress can yield adaptive long-term benefits, potentially transmitted trans-generationally. Physical training exposes individuals to metabolic, thermal, mechanical, and oxidative stressors, activating cell signaling pathways that regulate gene expression and adaptive responses, thereby enhancing stress tolerance-a phenomenon known as hormesis. Muscle memory is the capacity of skeletal muscle to respond differently to environmental stimuli in an adaptive (positive) or maladaptive (negative) manner if the stimuli have been encountered previously. The Repeated Bout Effect encompasses our skeletal muscle capacity to activate an intrinsic protective mechanism that reacts to eccentric exercise-induced damage by activating an adaptive response that resists subsequent damage stimuli. Deciphering the molecular mechanism of this phenomenon would allow the incorporation of muscle memory in training programs for professional athletes, active individuals looking for the health benefits of exercise training, and patients with "exercise intolerance." Moreover, enhancing the adaptive response of muscle memory could promote healing in individuals who traditionally do not recover after immobilization. The improvement could be part of an exercise program but could also be targeted pharmacologically. This review explores Repeated Bout Effect mechanisms: neural adaptations, tendon and muscle fiber property changes, extracellular matrix remodeling, and improved inflammatory responses.

Molecular mechanisms of cancer cachexia. Role of exercise training.

Cancer-associated cachexia represents a multifactorial syndrome mainly characterized by muscle mass loss, which causes both a decrease in quality of life and anti-cancer therapy failure, among other consequences. The definition and diagnostic criteria of cachexia have changed and improved over time, including three different stages (pre-cachexia, cachexia, and refractory cachexia) and objective diagnostic markers. This metabolic wasting syndrome is characterized by a negative protein balance, and anti-cancer drugs like chemotherapy or immunotherapy exacerbate it through relatively unknown mechanisms. Due to its complexity, cachexia management involves a multidisciplinary strategy including not only nutritional and pharmacological interventions. Physical exercise has been proposed as a strategy to counteract the effects of cachexia on skeletal muscle, as it influences the mechanisms involved in the disease such as protein turnover, inflammation, oxidative stress, and mitochondrial dysfunction. This review will summarize the experimental and clinical evidence of the impact of physical exercise on cancer-associated cachexia.

Real-Life Outcomes of a Multicomponent Exercise Intervention in Community-Dwelling Frail Older Adults and Its Association with Nutritional-Related Factors.

Most of the studies on physical exercise in older adults have been conducted through randomized clinical trials performed under tight experimental conditions. Data regarding Real-Life physical exercise intervention programs in older adults with different conditions and in different settings, are lacking. This is an interventional, prospective and pragmatic Real-Life study in which fifty sedentary and frail individuals were enrolled. We aimed at determining if a Real-Life exercise intervention outweighs previously reported improvements in a Clinical Trial (NCT02331459). We found higher improvements in the Real-Life exercise intervention vs. the Clinical Trial in functional parameters, such as Fried's frailty criteria, Tinetti, Barthel and Lawton & Brody scales. Similar results were found in the dietary habits, emotional and social networking outcomes determined through the Short-MNA, Yesavage, EuroQol and Duke scales. The Real-Life intervention led to a significant reduction in the number of falls, visits to the primary care centers and emergency visits when compared to the results of our previously published Clinical Trial. The implementation of a Real-Life exercise intervention is feasible and should be a major priority to improve health-span in the older population.

The radiographic assessment of lung edema score of lung edema severity correlates with inflammatory parameters in patients with coronavirus disease 2019-Potential new admission biomarkers to predict coronavirus disease 2019 worsening.

Background: Coronavirus disease 2019 (COVID-19) has placed enormous pressure on intensive care units (ICUs) and on healthcare systems in general. A deeper understanding of the pathophysiology of the most severe forms of COVID-19 would help guide the development of more effective interventions. Herein, we characterized the inflammatory state of patients with COVID-19 of varying degrees of severity to identify admission biomarkers for predicting COVID-19 worsening. Design: Admission blood samples were obtained from 78 patients with COVID-19. Radiographic assessment of lung edema (RALE) scoring was calculated by imaging. Platelet and leukocyte counts were measured by flow cytometry, and plasma levels of C-reactive protein were assessed by immunoturbidimetry, and interleukin (IL)-8/CXCL8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and monocyte chemoattractant protein-1 (MCP-1/CCL2) levels by enzyme-linked immunosorbent assay (ELISA). Results: The RALE score correlated with several admission hemogram (platelets, neutrophils, and lymphocytes) and inflammatory (IL-8/CXCL8, MCP-1/CCL2, IL-10, and C-reactive protein) parameters. COVID-19 worsening, based on the need for oxygen (Δoxygen supply) during hospitalization, correlated negatively with admission lymphocyte counts but positively with neutrophil-to-lymphocyte ratio and with plasma levels of the inflammatory parameters correlating with RALE score. Conclusion: Our data indicate a correlation between the RALE score and Δoxygen supply and admission inflammatory status. The identification of a panel of biomarkers that reflect COVID severity might be useful to predict disease worsening during hospitalization and to guide clinical management of COVID-19-related complications. Finally, therapies targeting IL-8/CXCL8- or IL-10 activity may offer therapeutic approaches in COVID-19 treatment.

Role of Redox Signaling and Inflammation in Skeletal Muscle Adaptations to Training.

The inflammatory response to exercise-induced muscle damage has been extensively described. Exercise has important modulatory effects on immune function. These effects are mediated by diverse factors including pro-inflammatory cytokines, classical stress hormones, and hemodynamic effects leading to cell redistribution. As has been reported regarding oxidative stress, inflammation can have both detrimental and beneficial effects in skeletal muscle. In this review we will address the role of inflammation on protein metabolism in skeletal muscle. Specifically, we will review studies showing that treatment with cyclooxygenase-inhibiting drugs modulate the protein synthesis response to one bout of resistance exercise and to training. Understanding how these drugs work is important for the millions of individuals worldwide that consume them regularly. We will also discuss the importance of reactive oxygen species and inflammatory cytokines in muscle adaptations to exercise and the Janus faced of the use of antioxidant and anti-inflammatory drugs by athletes for optimizing their performance, especially during the periods in which muscle hypertrophy is expected.

Role of free radicals and antioxidant signaling in skeletal muscle health and pathology.

Skeletal muscle contraction, growth, differentiation and adaptation are governed by complicated biological mechanisms still being studied intensively. Generation of reactive oxygen and nitrogen species (RS) is one of the most prominent events during contractile activity that could influence muscle function and health. While RS generation is known to cause oxidative stress, activate certain pathogenic pathways and aging, they also serve as useful signaling molecules to regulate gene expression of proteins and enzymes that play a vital role in the normal muscle function and defense against detrimental effects of RS. The purpose of the present review is two-fold: first, to provide an overview of cell signaling controlled by a redox sensitive mechanism and its impact on skeletal muscle health and function; and second, to review the various muscular diseases and disorders that have an etiological origin of RS overproduction and/or inadequate antioxidant defense. Given the physiological role of skeletal muscle we will emphasize the importance of physical exercise in promoting cellular antioxidant defense and its benefits in the maintenance of muscle health.

Interplay of oxidants and antioxidants during exercise: implications for muscle health.

Muscle contraction results in generation of reactive oxygen and nitrogen species (RONS) at a rate determined by the intensity, frequency, and duration of the exercise protocols. Strenuous exercise causes oxidation of protein, lipid, and DNA, release of cytosolic enzymes, and other signs of cell damage; however, only exhaustive exercise is detrimental. Indeed, the regulation of vascular tone, the excitation-contraction coupling, growth, and differentiation in skeletal muscle, are governed in part by RONS. This is accomplished by RONS interaction with redox-sensitive transcription factors, leading to increased gene expression of antioxidant enzymes, cytoprotective proteins, and other enzymes involved in muscle metabolic functions. However, high levels of RONS generation are known to cause oxidative stress, activate certain pathogenic pathways, and accelerate aging. This article reviews research from the past decades on the interplay of oxidants and antioxidants in skeletal muscle, with particular reference to increased contractile activity. Adaptation of muscle to increased oxidative stress and the potential mechanisms involved will be highlighted. The role of redox-controlled cell signaling in skeletal muscle health and function is also described.

Role of nuclear factor kappaB and mitogen-activated protein kinase signaling in exercise-induced antioxidant enzyme adaptation.

Activation of nuclear factor (NF) kappaB and mitogen-activated protein kinase (MAPK) pathways in skeletal muscle has been shown to enhance the gene expression of several enzymes that play an important role in maintaining oxidant-antioxidant homeostasis, such as mitochondrial superoxide dismutase (MnSOD) and inducible nitric oxide synthase (iNOS). While an acute bout of exercise activates NF kappaB and MAPK signaling and upregulates MnSOD and iNOS, administration of chemical agents that suppress reactive oxygen species (ROS) production can cause attenuation of exercise-induced MnSOD and iNOS expression. Thus, ROS generation during exercise may have duel effects: the infliction of oxidative stress and damage, and the stimulation of adaptive responses favoring long-term protection. This scenario explains why animals and humans involved in exercise training have demonstrated increased resistance to oxidative damage under a wide range of physiological and pathological stresses.

Exercise and hormesis: activation of cellular antioxidant signaling pathway.

Contraction-induced production of reactive oxygen species (ROS) has been shown to cause oxidative stress to skeletal muscle. As an adaptive response, muscle antioxidant defense systems are upregulated after heavy exercise. Nuclear factor (NF) kappaB and mitogen-activated protein kinases (MAPKs) are the major oxidative stress-sensitive signal transduction pathways in mammalian tissues. Activation of NF-kappaB signaling cascade has been shown to enhance the gene expression of important enzymes, such as mitochondrial superoxide dismutase (MnSOD) and inducible nitric oxide synthase (iNOS). MAPK activations are involved in a variety of cellular functions including growth, proliferation, and adaptation. We investigated the effect of an acute bout of exercise on NF-kappaB and MAPK signaling, as well as on the time course of activation, in rat skeletal muscle. In addition, we studied the role of ROS in the exercise-induced upregulation of MnSOD and iNOS, and the potential interactions of NF-kappaB and MAPK in the signaling of these enzymes. Our data suggest that ROS may serve as messenger molecules to activate adaptive responses through these redox-sensitive signaling pathways to maintain cellular oxidant-antioxidant homeostasis during exercise.