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1.
Cells ; 10(10)2021 09 23.
Article in English | MEDLINE | ID: covidwho-1438524

ABSTRACT

The ability of the ribonucleic acid (RNA) to self-replicate, combined with a unique cocktail of chemical properties, suggested the existence of an RNA world at the origin of life. Nowadays, this hypothesis is supported by innovative high-throughput and biochemical approaches, which definitively revealed the essential contribution of RNA-mediated mechanisms to the regulation of fundamental processes of life. With the recent development of SARS-CoV-2 mRNA-based vaccines, the potential of RNA as a therapeutic tool has received public attention. Due to its intrinsic single-stranded nature and the ease with which it is synthesized in vitro, RNA indeed represents the most suitable tool for the development of drugs encompassing every type of human pathology. The maximum effectiveness and biochemical versatility is achieved in the guise of non-coding RNAs (ncRNAs), which are emerging as multifaceted regulators of tissue specification and homeostasis. Here, we report examples of coding and ncRNAs involved in muscle regeneration and discuss their potential as therapeutic tools. Small ncRNAs, such as miRNA and siRNA, have been successfully applied in the treatment of several diseases. The use of longer molecules, such as lncRNA and circRNA, is less advanced. However, based on the peculiar properties discussed below, they represent an innovative pool of RNA biomarkers and possible targets of clinical value.


Subject(s)
MicroRNAs/metabolism , Muscle, Skeletal/metabolism , Muscle, Skeletal/pathology , RNA, Messenger/metabolism , RNA, Untranslated/genetics , Regeneration , Animals , Biomarkers/metabolism , COVID-19 , Homeostasis , Humans , Mice , Muscle, Skeletal/virology , Myocardium/metabolism , Origin of Life , RNA, Circular , RNA, Long Noncoding/genetics , RNA, Small Interfering/metabolism , RNA, Small Untranslated/genetics , RNA, Viral/metabolism , SARS-CoV-2/genetics
2.
Scand J Med Sci Sports ; 31(12): 2249-2258, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1434834

ABSTRACT

The study aimed to determine the levels of skeletal muscle angiotensin-converting enzyme 2 (ACE2, the SARS-CoV-2 receptor) protein expression in men and women and assess whether ACE2 expression in skeletal muscle is associated with cardiorespiratory fitness and adiposity. The level of ACE2 in vastus lateralis muscle biopsies collected in previous studies from 170 men (age: 19-65 years, weight: 56-137 kg, BMI: 23-44) and 69 women (age: 18-55 years, weight: 41-126 kg, BMI: 22-39) was analyzed in duplicate by western blot. VO2 max was determined by ergospirometry and body composition by DXA. ACE2 protein expression was 1.8-fold higher in women than men (p = 0.001, n = 239). This sex difference disappeared after accounting for the percentage of body fat (fat %), VO2 max per kg of legs lean mass (VO2 max-LLM) and age (p = 0.47). Multiple regression analysis showed that the fat % (ß = 0.47) is the main predictor of the variability in ACE2 protein expression in skeletal muscle, explaining 5.2% of the variance. VO2 max-LLM had also predictive value (ß = 0.09). There was a significant fat % by VO2 max-LLM interaction, such that for subjects with low fat %, VO2 max-LLM was positively associated with ACE2 expression while as fat % increased the slope of the positive association between VO2 max-LLM and ACE2 was reduced. In conclusion, women express higher amounts of ACE2 in their skeletal muscles than men. This sexual dimorphism is mainly explained by sex differences in fat % and cardiorespiratory fitness. The percentage of body fat is the main predictor of the variability in ACE2 protein expression in human skeletal muscle.


Subject(s)
Adiposity , Angiotensin-Converting Enzyme 2/metabolism , COVID-19 , Cardiorespiratory Fitness , Exercise , Muscle, Skeletal/metabolism , Adolescent , Adult , Angiotensin-Converting Enzyme 2/genetics , Biopsy , COVID-19/complications , COVID-19/epidemiology , Cross-Sectional Studies , Energy Metabolism , Female , Humans , Male , Middle Aged , SARS-CoV-2 , Sex Factors , Young Adult
4.
JAMA Neurol ; 78(8): 948-960, 2021 08 01.
Article in English | MEDLINE | ID: covidwho-1265359

ABSTRACT

Importance: Myalgia, increased levels of creatine kinase, and persistent muscle weakness have been reported in patients with COVID-19. Objective: To study skeletal muscle and myocardial inflammation in patients with COVID-19 who had died. Design, Setting, and Participants: This case-control autopsy series was conducted in a university hospital as a multidisciplinary postmortem investigation. Patients with COVID-19 or other critical illnesses who had died between March 2020 and February 2021 and on whom an autopsy was performed were included. Individuals for whom informed consent to autopsy was available and the postmortem interval was less than 6 days were randomly selected. Individuals who were infected with SARS-CoV-2 per polymerase chain reaction test results and had clinical features suggestive of COVID-19 were compared with individuals with negative SARS-CoV-2 polymerase chain reaction test results and an absence of clinical features suggestive of COVID-19. Main Outcomes and Measures: Inflammation of skeletal muscle tissue was assessed by quantification of immune cell infiltrates, expression of major histocompatibility complex (MHC) class I and class II antigens on the sarcolemma, and a blinded evaluation on a visual analog scale ranging from absence of pathology to the most pronounced pathology. Inflammation of cardiac muscles was assessed by quantification of immune cell infiltrates. Results: Forty-three patients with COVID-19 (median [interquartile range] age, 72 [16] years; 31 men [72%]) and 11 patients with diseases other than COVID-19 (median [interquartile range] age, 71 [5] years; 7 men [64%]) were included. Skeletal muscle samples from the patients who died with COVID-19 showed a higher overall pathology score (mean [SD], 3.4 [1.8] vs 1.5 [1.0]; 95% CI, 0-3; P < .001) and a higher inflammation score (mean [SD], 3.5 [2.1] vs 1.0 [0.6]; 95% CI, 0-4; P < .001). Relevant expression of MHC class I antigens on the sarcolemma was present in 23 of 42 specimens from patients with COVID-19 (55%) and upregulation of MHC class II antigens in 7 of 42 specimens from patients with COVID-19 (17%), but neither were found in any of the controls. Increased numbers of natural killer cells (median [interquartile range], 8 [8] vs 3 [4] cells per 10 high-power fields; 95% CI, 1-10 cells per 10 high-power fields; P < .001) were found. Skeletal muscles showed more inflammatory features than cardiac muscles, and inflammation was most pronounced in patients with COVID-19 with chronic courses. In some muscle specimens, SARS-CoV-2 RNA was detected by reverse transcription-polymerase chain reaction, but no evidence for a direct viral infection of myofibers was found by immunohistochemistry and electron microscopy. Conclusions and Relevance: In this case-control study of patients who had died with and without COVID-19, most individuals with severe COVID-19 showed signs of myositis ranging from mild to severe. Inflammation of skeletal muscles was associated with the duration of illness and was more pronounced than cardiac inflammation. Detection of viral load was low or negative in most skeletal and cardiac muscles and probably attributable to circulating viral RNA rather than genuine infection of myocytes. This suggests that SARS-CoV-2 may be associated with a postinfectious, immune-mediated myopathy.


Subject(s)
COVID-19/pathology , Muscle, Skeletal/pathology , Myocarditis/pathology , Myocardium/pathology , Myositis/pathology , Aged , Aged, 80 and over , Autopsy , CD8-Positive T-Lymphocytes/pathology , COVID-19/metabolism , COVID-19 Nucleic Acid Testing , COVID-19 Serological Testing , Case-Control Studies , Female , Histocompatibility Antigens Class I/metabolism , Histocompatibility Antigens Class II/metabolism , Humans , Killer Cells, Natural/pathology , Leukocytes/pathology , Macrophages/pathology , Male , Middle Aged , Muscle, Skeletal/metabolism , Myocarditis/metabolism , Myocardium/metabolism , Myositis/metabolism , RNA, Viral/metabolism , SARS-CoV-2 , Sarcolemma/metabolism , Time Factors
5.
Obesity (Silver Spring) ; 29(9): 1423-1426, 2021 09.
Article in English | MEDLINE | ID: covidwho-1217406

ABSTRACT

OBJECTIVE: Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) uses the host's angiotensin-converting enzyme 2 (ACE2) as a cellular entry point. Therefore, modulating ACE2 might impact SARS-CoV-2 viral replication, shedding, and coronavirus disease 2019 (COVID-19) severity. Here, it was investigated whether the angiotensin II type 1 receptor blocker valsartan alters the expression of renin-angiotensin system (RAS) components, including ACE2, in human adipose tissue (AT) and skeletal muscle. METHODS: A randomized, double-blind, placebo-controlled clinical trial was performed, in which 36 participants (BMI 31.0 ± 0.8 kg/m2 ) with impaired glucose metabolism received either valsartan or placebo for 26 weeks. Before and after 26 weeks' treatment, abdominal subcutaneous AT and skeletal muscle biopsies were obtained, and gene expression of RAS components was measured by quantitative reverse transcription polymerase chain reaction. RESULTS: Valsartan treatment did not significantly impact the expression of RAS components, including ACE2, in AT and skeletal muscle. CONCLUSIONS: Given the pivotal role of ACE2 in SARS-CoV-2 spread and the clinical outcomes in COVID-19 patients, the data suggest that the putative beneficial effects of angiotensin II type 1 receptor blockers on the clinical outcomes of patients with COVID-19 may not be mediated through altered ACE2 expression in abdominal subcutaneous AT.


Subject(s)
Angiotensin II Type 1 Receptor Blockers , Angiotensin-Converting Enzyme 2/metabolism , Renin-Angiotensin System , Valsartan , Adipose Tissue/metabolism , Angiotensin II Type 1 Receptor Blockers/pharmacology , COVID-19 , Humans , Muscle, Skeletal/metabolism , Valsartan/pharmacology
6.
Nature ; 588(7838): 466-472, 2020 12.
Article in English | MEDLINE | ID: covidwho-1075229

ABSTRACT

Cardiovascular disease is the leading cause of death worldwide. Advanced insights into disease mechanisms and therapeutic strategies require a deeper understanding of the molecular processes involved in the healthy heart. Knowledge of the full repertoire of cardiac cells and their gene expression profiles is a fundamental first step in this endeavour. Here, using state-of-the-art analyses of large-scale single-cell and single-nucleus transcriptomes, we characterize six anatomical adult heart regions. Our results highlight the cellular heterogeneity of cardiomyocytes, pericytes and fibroblasts, and reveal distinct atrial and ventricular subsets of cells with diverse developmental origins and specialized properties. We define the complexity of the cardiac vasculature and its changes along the arterio-venous axis. In the immune compartment, we identify cardiac-resident macrophages with inflammatory and protective transcriptional signatures. Furthermore, analyses of cell-to-cell interactions highlight different networks of macrophages, fibroblasts and cardiomyocytes between atria and ventricles that are distinct from those of skeletal muscle. Our human cardiac cell atlas improves our understanding of the human heart and provides a valuable reference for future studies.


Subject(s)
Myocardium/cytology , Single-Cell Analysis , Transcriptome , Adipocytes/classification , Adipocytes/metabolism , Adult , Angiotensin-Converting Enzyme 2/analysis , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Epithelial Cells/classification , Epithelial Cells/metabolism , Epithelium , Female , Fibroblasts/classification , Fibroblasts/metabolism , Gene Expression Profiling , Genome-Wide Association Study , Heart Atria/anatomy & histology , Heart Atria/cytology , Heart Atria/innervation , Heart Ventricles/anatomy & histology , Heart Ventricles/cytology , Heart Ventricles/innervation , Homeostasis/immunology , Humans , Macrophages/immunology , Macrophages/metabolism , Male , Muscle, Skeletal/cytology , Muscle, Skeletal/metabolism , Myocytes, Cardiac/classification , Myocytes, Cardiac/metabolism , Neurons/classification , Neurons/metabolism , Pericytes/classification , Pericytes/metabolism , Receptors, Coronavirus/analysis , Receptors, Coronavirus/genetics , Receptors, Coronavirus/metabolism , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Stromal Cells/classification , Stromal Cells/metabolism
7.
Nutrients ; 13(2)2021 Feb 04.
Article in English | MEDLINE | ID: covidwho-1069851

ABSTRACT

Post-viral fatigue syndrome (PVFS) is a widespread chronic neurological disease with no definite etiological factor(s), no actual diagnostic test, and no approved pharmacological treatment, therapy, or cure. Among other features, PVFS could be accompanied by various irregularities in creatine metabolism, perturbing either tissue levels of creatine in the brain, the rates of phosphocreatine resynthesis in the skeletal muscle, or the concentrations of the enzyme creatine kinase in the blood. Furthermore, supplemental creatine and related guanidino compounds appear to impact both patient- and clinician-reported outcomes in syndromes and maladies with chronic fatigue. This paper critically overviews the most common disturbances in creatine metabolism in various PVFS populations, summarizes human trials on dietary creatine and creatine analogs in the syndrome, and discusses new frontiers and open questions for using creatine in a post-COVID-19 world.


Subject(s)
Creatine/administration & dosage , Creatine/metabolism , Fatigue Syndrome, Chronic/diet therapy , Fatigue Syndrome, Chronic/metabolism , Biomarkers/metabolism , Brain/metabolism , COVID-19/complications , Creatine/analogs & derivatives , Dietary Supplements , Fatigue Syndrome, Chronic/diagnosis , Humans , Muscle, Skeletal/metabolism , Randomized Controlled Trials as Topic
8.
Int J Mol Sci ; 21(23)2020 Dec 03.
Article in English | MEDLINE | ID: covidwho-965280

ABSTRACT

Glucocorticoids are drugs of choice in Duchenne muscular dystrophy (DMD), prolonging patients' ambulation. Their mode of action at the protein level is not completely understood. In DMD, muscle tissue is replaced by fibrotic tissue produced by fibroblasts, reducing mobility. Nuclear factor of activated T-cells 5 (NFAT5) is involved in fibroblast proliferation. By treating one DMD fibroblast cell culture and one of unaffected skeletal muscle fibroblasts with methylprednisolone (MP) or hydrocortisone (HC) for 24 h or 12 d, the antiproliferative properties of glucocorticoids could be unraveled. NFAT5 localization and expression was explored by immunocytochemistry (ICC), Western blotting (WB) and RT-qPCR. NFAT5 and glucocorticoid receptor (GR) colocalization was measured by ImageJ. GR siRNA was used, evaluating GR's influence on NFAT5 expression during MP and HC treatment. Cell proliferation was monitored by IncuCyte ZOOM. In DMD fibroblasts, treatment with MP for 24 h induced dots (ICC) positive for NFAT5 and colocalizing with GR. After 12 d of MP or HC in DMD fibroblasts, NFAT5 expression was decreased (RT-qPCR and WB) and growth arrest was observed (Incucyte ZOOM), whereas NFAT5 expression and cell growth remained unchanged in unaffected skeletal muscle fibroblasts. This study may help understand the antiproliferative properties of glucocorticoids in DMD fibroblasts.


Subject(s)
Fibroblasts/drug effects , Fibroblasts/metabolism , Glucocorticoids/pharmacology , Receptors, Glucocorticoid/metabolism , Transcription Factors/metabolism , Cell Proliferation/drug effects , Cells, Cultured , Dose-Response Relationship, Drug , Fluorescent Antibody Technique , Humans , Hydrocortisone/pharmacology , Methylprednisolone/pharmacology , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , Muscular Dystrophy, Duchenne/genetics , Muscular Dystrophy, Duchenne/metabolism , Protein Binding
9.
Int J Mol Sci ; 21(21)2020 Oct 24.
Article in English | MEDLINE | ID: covidwho-895370

ABSTRACT

Severe acute respiratory syndrome coronavirus (SARS-CoV-2) has produced significant health emergencies worldwide, resulting in the declaration by the World Health Organization of the coronavirus disease 2019 (COVID-19) pandemic. Acute respiratory syndrome seems to be the most common manifestation of COVID-19. A high proportion of patients require intensive care unit admission and mechanical ventilation (MV) to survive. It has been well established that angiotensin-converting enzyme type 2 (ACE2) is the primary cellular receptor for SARS-CoV-2. ACE2 belongs to the renin-angiotensin system (RAS), composed of several peptides, such as angiotensin II (Ang II) and angiotensin (1-7) (Ang-(1-7)). Both peptides regulate muscle mass and function. It has been described that SARS-CoV-2 infection, by direct and indirect mechanisms, affects a broad range of organ systems. In the skeletal muscle, through unbalanced RAS activity, SARS-CoV-2 could induce severe consequences such as loss of muscle mass, strength, and physical function, which will delay and interfere with the recovery process of patients with COVID-19. This article discusses the relationship between RAS, SARS-CoV-2, skeletal muscle, and the potentially harmful consequences for skeletal muscle in patients currently infected with and recovering from COVID-19.


Subject(s)
Coronavirus Infections/metabolism , Muscle, Skeletal/physiopathology , Muscular Atrophy/etiology , Pneumonia, Viral/metabolism , Renin-Angiotensin System , Animals , COVID-19 , Coronavirus Infections/complications , Coronavirus Infections/physiopathology , Humans , Muscle, Skeletal/metabolism , Pandemics , Pneumonia, Viral/complications , Pneumonia, Viral/physiopathology
11.
J Clin Monit Comput ; 35(3): 661-662, 2021 May.
Article in English | MEDLINE | ID: covidwho-649924

ABSTRACT

OBJECTIVE: Objective of this case report is to draw attention to a less known thrombotic complication associated with COVID-19, i.e., thrombosis of both radial arteries, with possible (long-term) consequences. THE CASE: In our COVID-19 ICU a 49-year-old male patient was admitted, with past medical history of obesity, smoking and diabetes, but no reported atherosclerotic complications. The patient had been admitted with severe hypoxemia and multiple pulmonary emboli were CT-confirmed. ICU-treatment included mechanical ventilation and therapeutic anticoagulation. Preparing the insertion of a new radial artery catheter for invasive blood pressure measurement and blood sampling, we detected that both radial arteries were non-pulsating and occluded: (a) Sonography showed the typical anatomical localization of both radial and ulnar arteries. However, Doppler-derived flow-signals could only be obtained from the ulnar arteries. (b) To test collateral arterial supply of the hand, a pulse-oximeter was placed on the index finger. Thereafter, the ulnar artery at the wrist was compressed. This compression caused an immediate loss of the finger's pulse-oximetry perfusion signal. The effect was reversible upon release of the ulnar artery. (c) To test for collateral perfusion undetectable by pulse-oximetry, we measured regional oxygen saturation (rSO2) of the thenar muscle by near-infrared spectroscopy (NIRS). Confirming our findings above, ulnar arterial compression demonstrated that thenar rSO2 was dependent on ulnar artery flow. The described development of bilateral radial artery occlusion in a relatively young and therapeutically anticoagulated patient with no history of atherosclerosis was unexpected. CONCLUSIONS: Since COVID-19 patients are at increased risk for arterial occlusion, it appears advisable to meticulously check for adequacy of collateral (hand-) perfusion, avoiding the harm of hand ischemia if interventions (e.g., catheterizations) at the radial or ulnar artery are intended.


Subject(s)
Arterial Occlusive Diseases/diagnostic imaging , Arterial Occlusive Diseases/etiology , COVID-19/complications , Radial Artery , SARS-CoV-2 , Arterial Occlusive Diseases/physiopathology , COVID-19/diagnostic imaging , COVID-19/physiopathology , Hand/blood supply , Hand/diagnostic imaging , Humans , Male , Middle Aged , Muscle, Skeletal/blood supply , Muscle, Skeletal/metabolism , Netherlands , Oximetry , Oxygen Consumption , Pandemics , Radial Artery/diagnostic imaging , Radial Artery/physiopathology , Regional Blood Flow , Spectroscopy, Near-Infrared , Ulnar Artery/diagnostic imaging , Ultrasonography, Doppler
12.
Mol Med ; 26(1): 69, 2020 07 08.
Article in English | MEDLINE | ID: covidwho-635101

ABSTRACT

BACKGROUND: We previously showed that the autophagy inhibitor chloroquine (CQ) increases inflammatory cleaved caspase-1 activity in myocytes, and that caspase-1/11 is protective in sterile liver injury. However, the role of caspase-1/11 in the recovery of muscle from ischemia caused by peripheral arterial disease is unknown. We hypothesized that caspase-1/11 mediates recovery in muscle via effects on autophagy and this is modulated by CQ. METHODS: C57Bl/6 J (WT) and caspase-1/11 double-knockout (KO) mice underwent femoral artery ligation (a model of hind-limb ischemia) with or without CQ (50 mg/kg IP every 2nd day). CQ effects on autophagosome formation, microtubule associated protein 1A/1B-light chain 3 (LC3), and caspase-1 expression was measured using electron microscopy and immunofluorescence. Laser Doppler perfusion imaging documented perfusion every 7 days. After 21 days, in situ physiologic testing in tibialis anterior muscle assessed peak force contraction, and myocyte size and fibrosis was also measured. Muscle satellite cell (MuSC) oxygen consumption rate (OCR) and extracellular acidification rate was measured. Caspase-1 and glycolytic enzyme expression was detected by Western blot. RESULTS: CQ increased autophagosomes, LC3 consolidation, total caspase-1 expression and cleaved caspase-1 in muscle. Perfusion, fibrosis, myofiber regeneration, muscle contraction, MuSC fusion, OCR, ECAR and glycolytic enzyme expression was variably affected by CQ depending on presence of caspase-1/11. CQ decreased perfusion recovery, fibrosis and myofiber size in WT but not caspase-1/11KO mice. CQ diminished peak force in whole muscle, and myocyte fusion in MuSC and these effects were exacerbated in caspase-1/11KO mice. CQ reductions in maximal respiration and ATP production were reduced in caspase-1/11KO mice. Caspase-1/11KO MuSC had significant increases in protein kinase isoforms and aldolase with decreased ECAR. CONCLUSION: Caspase-1/11 signaling affects the response to ischemia in muscle and effects are variably modulated by CQ. This may be critically important for disease treated with CQ and its derivatives, including novel viral diseases (e.g. COVID-19) that are expected to affect patients with comorbidities like cardiovascular disease.


Subject(s)
Caspase 1/metabolism , Caspases, Initiator/metabolism , Chloroquine/pharmacology , Coronavirus Infections/pathology , Ischemia/pathology , Muscle, Skeletal/pathology , Pneumonia, Viral/pathology , Animals , Autophagosomes/metabolism , Autophagy/drug effects , Betacoronavirus , COVID-19 , Coronavirus Infections/drug therapy , Glycolysis/physiology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Microtubule-Associated Proteins/metabolism , Muscle Cells/metabolism , Muscle Development , Muscle, Skeletal/metabolism , Neovascularization, Physiologic , Oxidative Phosphorylation , Pandemics , Peripheral Arterial Disease/pathology , Pneumonia, Viral/drug therapy , Regeneration , SARS-CoV-2 , Signal Transduction
13.
Int J Mol Sci ; 21(13)2020 Jun 30.
Article in English | MEDLINE | ID: covidwho-635082

ABSTRACT

Obesity is a characteristic of COVID-19 patients and the risk of malnutrition can be underestimated due to excess of fat: a paradoxical danger. Long ICU hospitalization exposes patients to a high risk of wasting and loss of lean body mass. The complex management precludes the detection of anthropometric parameters for the definition and monitoring of the nutritional status. The use of imaging diagnostics for body composition could help to recognize and treat patients at increased risk of wasting with targeted pathways. COVID-19 patients admitted to the ICU underwent computed tomography within 24 hours and about 20 days later, to evaluate the parameters of the body and liver composition. The main results were the loss of the lean mass index and a greater increase in liver attenuation in obese subjects. These could be co-caused by COVID-19, prolonged bed rest, the complex medical nutritional therapy, and the starting condition of low-grade inflammation of the obese. The assessment of nutritional status, with body composition applied to imaging diagnostics and metabolic profiles in COVID-19, will assist in prescribing appropriate medical nutritional therapy. This will reduce recovery times and complications caused by frailty.


Subject(s)
Cachexia , Coronavirus Infections/pathology , Obesity/pathology , Pneumonia, Viral/pathology , Adult , Aged , Betacoronavirus/isolation & purification , Body Composition , COVID-19 , Coronavirus Infections/complications , Coronavirus Infections/diagnostic imaging , Female , Humans , Liver/diagnostic imaging , Liver/metabolism , Male , Middle Aged , Muscle, Skeletal/diagnostic imaging , Muscle, Skeletal/metabolism , Nutritional Status , Obesity/complications , Pandemics , Pneumonia, Viral/complications , Pneumonia, Viral/diagnostic imaging , Prospective Studies , Risk Factors , SARS-CoV-2 , Tomography, X-Ray Computed
16.
Eur J Sport Sci ; 21(4): 614-635, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-245123

ABSTRACT

The COVID-19 pandemic is an unprecedented health crisis as entire populations have been asked to self-isolate and live in home-confinement for several weeks to months, which in itself represents a physiological challenge with significant health risks. This paper describes the impact of sedentarism on the human body at the level of the muscular, cardiovascular, metabolic, endocrine and nervous systems and is based on evidence from several models of inactivity, including bed rest, unilateral limb suspension, and step-reduction. Data form these studies show that muscle wasting occurs rapidly, being detectable within two days of inactivity. This loss of muscle mass is associated with fibre denervation, neuromuscular junction damage and upregulation of protein breakdown, but is mostly explained by the suppression of muscle protein synthesis. Inactivity also affects glucose homeostasis as just few days of step reduction or bed rest, reduce insulin sensitivity, principally in muscle. Additionally, aerobic capacity is impaired at all levels of the O2 cascade, from the cardiovascular system, including peripheral circulation, to skeletal muscle oxidative function. Positive energy balance during physical inactivity is associated with fat deposition, associated with systemic inflammation and activation of antioxidant defences, exacerbating muscle loss. Importantly, these deleterious effects of inactivity can be diminished by routine exercise practice, but the exercise dose-response relationship is currently unknown. Nevertheless, low to medium-intensity high volume resistive exercise, easily implementable in home-settings, will have positive effects, particularly if combined with a 15-25% reduction in daily energy intake. This combined regimen seems ideal for preserving neuromuscular, metabolic and cardiovascular health.


Subject(s)
Communicable Disease Control/methods , Energy Metabolism , Exercise/physiology , Health Behavior , Muscle, Skeletal , Pandemics , Sedentary Behavior , Adipose Tissue/metabolism , Cardiovascular System/metabolism , Endocrine System , Energy Intake , Humans , Insulin Resistance , Muscle, Skeletal/metabolism , Muscle, Skeletal/physiopathology , Muscular Atrophy , Oxygen/metabolism , Physical Distancing , Physical Exertion/physiology , Resistance Training , SARS-CoV-2
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