Luiz Augusto da Silva*

lasilva7@hotmail.com

Marcos Roberto Brasil**

brasilmr@hotmail.com.br

*Programa de Pós-Graduação em Promoção da Saúde da UniGuairacá

**Doutor em Educação Física pela Universidade Estadual de Maringá

Professor Assistente da Universidade Estadual do Centro-Oeste (UNICENTRO)

Tutor EAD-SR do Centro de Ensino Superior de Maringá (UNICESUMAR)

Professor Titular do Centro Universitário Guairacá (UNIGUAIRACÁ)

(Brasil)

Reception: 05/08/2023 - Acceptance: 09/09/2023

1st Review: 08/22/2023 - 2nd Review: 09/06/2023

Accessible document. Law N° 26.653. WCAG 2.0

Suggested reference: Silva, L.A. da, & Brasil, M.R. (2023). Physical Exercise Recommendations in Muscle and Weight Loss Due to COVID-19. A Narrative Review. Lecturas: Educación Física y Deportes, 28(307), 179-190. https://doi.org/10.46642/efd.v28i307.4029

 

Abstract

    Introduction: A muscle loss is associated with a symptomatic Coronavirus disease 2019 (COVID-19) by histologic and body compositions and biochemical analysis in quantification measures. Is unclear the mechanism for muscle damage in these patients, but the tomographic measurement is a result that appears in the analyses in hospitalized patients. Objective: The aim of this study is to evaluate the influence of COVID-19 on weight loss, cachexia and sarcopenia. Methods: The literature review was conducted according to the SANRA Statement utilizing PubMed, Lilacs, Google Scholar and Cochrane Library databases. First, to identify relevant publications about COVID-19 and muscle and weight loss, the combined search terms were used: (1) COVID-19 OR SARS-CoV-2 (2) cachexia OR muscle wasting and (3) exercise OR nutrition. Results and conclusions: Previous information related the cytokines, nutrition, pharmacological treatment, physical inactivity during intensive care unit (ICU) stays, mechanical ventilation are associated with de sarcopenia and cachexia in COVID-19 patients. In studies area association between imaging and physical test performance, anthropometric measures and muscle dystrophy blood marks.

    Keywords: Physical activity. Cytokine storm. Skeletalmuscle. Malnutrition.

 

Resumo

    Introdução: Uma perda muscular está associada a uma doença sintomática de Coronavírus 2019 (COVID-19) por composições histológicas e corporais e análises bioquímicas em medidas de quantificação. Não está claro o mecanismo de lesão muscular nesses pacientes, mas a medida tomográfica é um resultado que aparece nas análises em pacientes internados. Objetivo: O objetivo deste estudo é avaliar a influência do COVID-19 na perda de peso, caquexia e sarcopenia. Métodos: A revisão da literatura foi realizada de acordo com a Declaração SANRA (escala para avaliação da qualidade de artigos de revisão narrativa) utilizando os bancos de dados PubMed, Lilacs, Google Scholar e Cochrane Library. Primeiro, para identificar publicações relevantes sobre COVID-19 e perda muscular e de peso, foram usados os termos de pesquisa combinados: (1) COVID-19 OR SARS-CoV-2 (2) caquexia OR perda de massa muscular e (3) exercício OR nutrição. Resultados e conclusões: Informações prévias relacionadas a citocinas, nutrição, tratamento farmacológico, inatividade física durante internações na unidade de terapia intensiva (UTI), ventilação mecânica estão associadas à de sarcopenia e caquexia em pacientes com COVID-19. Na área de estudos existe associação entre exames de imagem e desempenho em testes físicos, medidas antropométricas e marcas sanguíneas de distrofia muscular.

    Unitermos: Atividade física. Tempestade de citocinas. Músculo esquelético. Desnutrição.

 

Resumen

    Introducción: La pérdida muscular se asocia con la enfermedad por Coronavirus 2019 (COVID-19) sintomática mediante composiciones histológicas, corporales y análisis bioquímicos en mediciones de cuantificación. El mecanismo de lesión muscular en estos pacientes no está claro, pero la medición tomográfica es un resultado que aparece en los análisis de pacientes hospitalizados. Objetivo: El objetivo de este estudio es evaluar la influencia del COVID-19 en la pérdida de peso, caquexia y sarcopenia. Métodos: La revisión de la literatura se realizó de acuerdo con la Declaración SANRA (escala para la evaluación de la calidad de los artículos de revisión narrativa) utilizando las bases de datos PubMed, Lilacs, Google Scholar y Cochrane Library. Primero, para identificar publicaciones relevantes sobre COVID-19 y pérdida muscular y de peso, se utilizaron los términos de investigación combinados: (1) COVID-19 OR SARS-CoV-2 (2) caquexia OR pérdida de masa muscular e (3) ejercicio OR nutrición. Resultados y conclusiones: La información previa relacionada con citocinas, nutrición, tratamiento farmacológico, inactividad física durante los ingresos a unidades de cuidados intensivos (UCI), ventilación mecánica, se asocian con sarcopenia y caquexia en pacientes con COVID-19. En el área de estudio existe asociación entre los exámenes de imagen y el rendimiento en pruebas físicas, mediciones antropométricas y marcas sanguíneas de distrofia muscular.

    Palabras clave: Atividade física. Tempestad de citocinas. Músculo esquelético. Desnutrición.

 

Lecturas: Educación Física y Deportes, Vol. 28, Núm. 307, Dic. (2023)

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Introduction 

 

    The ongoing outbreak of COVID-19 in China has become the world's leading health headline and is causing great panic and public concern. On January 30, 2020, the World Health Organization (WHO) declared that the new coronavirus outbreak is a public health emergency of international interest. (Chen et al., 2020)

 

    There is a general consensus that regular sessions of moderate intensity exercise of short duration (that is, up to 45 minutes) are beneficial for the body's immune defense, particularly in older adults and people with chronic diseases. (Simpson et al., 2020)

 

    Physical fitness and moderate-intensity exercise training have been shown to improve immune responses to vaccination, reduce low-grade chronic inflammation and improve various immune markers in various disease states, including cancer, HIV, cardiovascular disease, diabetes, impairment cognitive and obesity. (Mehta et al., 2020)

 

    The immune system is very important for maintaining responses to complications that can come from stress, from physical exercise to diseases caused by viruses and bacteria, thus physical exercise performed with the appropriate intensity, between 40% to 60% of the maximum VO2, it becomes important for the maintenance of health and consequently maintenance of the necessary immune responses, so that a defense of the organism against the viruses that are attacking occurs (Jin et al., 2020). COVID-19 is a very important health situation, as for the risk group, 2% of this population has the possibility of death, requiring intervention by an effective treatment, vaccination, keeping the body healthy in times of pandemic due to seclusion.

 

    That is why this article has a very important function for society, as here we will show the real value of a healthy body capable of withstanding situations that lead to weakness caused by virulent exogenous factors endemic to the current society that has been affected since January 2020.The aim of this study is to evaluate the influence of COVID-19 on weight loss, cachexia and sarcopenia.

 

Methods 

 

    The literature review was conducted according to the SANRA Statement (Baethge, 2019) utilizing PubMed, Lilacs, Google Scholar and Cochrane Library databases. First, to identify relevant publications about COVID-19 and muscle and weight loss, the combined search terms were used: (1) COVID-19 OR SARS-CoV-2 (2) cachexia OR muscle wasting and (3) exercise OR nutrition. The inclusion criteria were studies published from April 2021 to May 2021. Afterwards, to further discuss the relationship between COVID-19 infection, diet and loss of weight and muscle mass, relevant articles from the nutrition and cachexia area (including clinical characteristics and symptoms) were included.

 

    The present study is a narrative literature review with a descriptive nature. The entire research was conducted between April and May 2021, involving a theoretical collection of information from major publication databases. Bibliographic searches were performed on PubMed, Lilacs, Google Scholar, and Cochrane Library databases. Data collection began with a guiding question, followed by the use of keywords: (1) COVID-19 OR SARS-CoV-2, (2) cachexia OR muscle wasting, and (3) exercise OR nutrition.

 

    In terms of inclusion criteria, scientific articles published within the last 10 years and available in open-access formats in any of the aforementioned databases were chosen. There was no language restriction, allowing for the inclusion of research in Portuguese, English, or Spanish.

 

    Excluded from the review were theses, dissertations, repeated articles, and those not aligned with the research theme. The references of included articles were consulted to identify other potentially eligible studies.

 

    The identified works were subjected to evaluation criteria, including publication year, title, abstract, and the quality of the full-text content. In this phase, all articles that clearly did not meet the criteria were excluded. Selected articles were analyzed through a full-text reading, and eligible articles were then identified.

 

How can COVID-19 induce weight loss, cachexia, and sarcopenia? 

 

    Once the virus entry occurs, the rapid viral replication and a series of reactions begin such as cellular damage, the cytokine storm and antibody-dependent enhancement. (Asrani et al., 2021; Briguglio, 2020)

 

    Therefore, COVID-19 was reported to be associated with malnutrition in some studies. Diarrhea, mild abdominal pain, nausea, vomiting, poor appetite and other symptoms were commonly reported and can cause reduction in food intake and/or absorption, and consequently weight loss (Virgens et al., 2020). In this regard, acute phase proteins such as C-reactive protein, ferritin, tumor necrosis factor-alpha (TNF-α), interleukin (IL) family factors, NF-κB, interferon-γ, fibroblast growth factor and others are synthesized. (Virgens et al., 2020, Singh, & Singh, 2022; Queiroz Júnior et al., 2023)

 

    All these processes are directly related to the increase of muscle proteolysis, albumin consumption and impaired metabolism of macronutrients which can contribute to the onset of malnutrition and cachexia (Jia et al., 2016). Cachexia is a complex metabolic syndrome associated with underlying illness and characterized by loss of muscle with or without loss of fat mass (Li et al., 2020). The clinical consequences of cachexia depend as much on the weight loss as on the systemic inflammation, which accompany the development of cachexia. (Baracos et al., 2018)

 

Possible mechanisms of muscle damage in COVID-19 

 

    Oxidative stress has an influence on hypercatabolism after excess production of pro-inflammatory cytokines, which causes damage to the muscle fiber (Virgens et al., 2020; Singh, & Singh, 2022; Queiroz Júnior et al., 2023). Other factors can influence muscle loss, including advanced age, which reduces muscle recovery time, metabolic and inflammatory diseases such as diabetes, obesity and cancer, and also a diet and influence on state protein-energy (Welch et al, 2020). The reduction of testosterone is influenced by the reduction of muscle integrity due to the excess of cytokines, which causes an increase in degeneration, and reduction of muscle tissue. (Tieland et al., 2018)

 

    In the context of COVID-19 infection, several factors related to the immune system and the body's metabolism are affected, including the regulation of inflammatory cytokines and processes related to muscle health. IL-6 are two proinflammatory cytokines that play essential roles in the body's immune response and can have significant impacts on muscle health. (Virgens et al., 2020)

 

    TNF-α is an inflammatory cytokine that plays a crucial role in the body's immune response to infection. In the context of COVID-19, elevated levels of TNF-α can be observed due to the activation of the immune system to combat the virus. However, excessively high levels of TNF-α can contribute to systemic inflammation, which, in turn, can lead to muscle degradation processes, such as increased catabolism of muscle proteins. This can result in a higher rate of Muscle Protein Breakdown (MPB) relative to Muscle Protein Synthesis (MPS), leading to muscle loss. (Singh, & Singh, 2022)

 

    IL-6 is another inflammatory cytokine that plays a crucial role in the body's immune and inflammatory response. During COVID-19 infection, levels of IL-6 tend to increase as part of the body's natural immune response. However, excessively high levels of IL-6 are associated with chronic inflammatory processes and can contribute to muscle degradation. IL-6 can also affect the regulation of the balance between MPS and MPB, with high levels of IL-6 favoring MPB over MPS, resulting in muscle loss.

 

    During COVID-19 infection, elevated levels of proinflammatory cytokines like TNF-α and IL-6 can trigger a systemic inflammatory response in the body. This chronic inflammation can contribute to increased degradation of muscle proteins (MPB) compared to the synthesis of muscle proteins (MPS), leading to muscle loss (Queiroz Júnior et al., 2023). It is important to note that the balance between these processes is complex and can be influenced by various factors, including the severity of the infection, the individual body's response, and other underlying health factors. Therefore, understanding these mechanisms is still evolving as research on the interaction between COVID-19 and muscle health continues to advance.

 

    Patients who have been admitted to hospital or intensive care units (ICU) bring a great reduction in body weight associated with muscle loss. This is due to some factors that influence the loss of muscle protein in a short period of time (Welch et al., 2020). These factors can be related to the pronated position and bed rest in a prolonged way, use of drugs such as dexamethasone and hydroxychloroquine, low adequate nutritional intake, systemic inflammation due to the increase in interleukins such as IL-6, IL8 and IL-10, leading to a cytokine storm, and mechanical ventilation and intubation (Welch et al., 2018) (Figure 1).

 

Abbreviations: TNF-α: tumor necrosis factor-alpha; IL-6: interleukin-6; 

MPB: Muscle Protein Breakdown; MPS: Muscle Protein Synthesis. Source: Author (2023)

 

Prevention and treatment of COVID-19 cachectic patients through physical exercise 

 

    Exercise may be an important countermeasure to prevent cachectic state induced by COVID-19 infection by improving the reserve capacity which increases the “health” fitness spectrum that can be lost due to the marked catabolic state caused by the factors previously cited.

 

    If a sedentary patient experiments a decrease in skeletal muscle mass, it’s expected that their levels decrease to a critical state compromising the health status and functional capacity. However, a patient with a good physical fitness and muscle mass previous to COVID-19 infection can lose some of their fitness level. In this context, some recent studies show an association between muscle strength, hospitalization and Hospital Length of Stay in patients with COVID-19 (Cheval et al., 2021; Gil et al., 2021). These data reinforce the importance of previous reserve capacity to prevent COVID-19 complications.

 

    Another mechanism by which exercise may prevent cachectic state is to its effects on risk factors that increase the severity of COVID-19 complications. In this sense exercise may prevent and treat high blood pressure, high blood glucose levels, improves body composition, reducing body fat and other cardiovascular risk factors which are associated with an increased risk for complication, hospitalization and a need for intensive care. (Tieland et al., 2018)

 

    Considering that an exacerbate inflammatory and oxidative stress state is a feature of COVID-19 induced cachectic state, the anti-inflammatory effects induced by both aerobic and resistance exercise, can help to reduce muscle mass damage-induced by the inflammatory cytokine storm. (Brandt et al., 2010; Pedersen et al., 2015)

 

Treatment by physical exercise 

 

    Exercise is a good alternative to rehabilitate or even revert some muscle alterations induced by a catabolic environment during COVID-19 infections and hospitalization. In this sense, both aerobic training (AT) and resistance exercise has been shown effective to increase lean body mass, even in periods of catabolic states. (Gleeson et al., 2011)

 

    Considering the anabolic potential to increase skeletal muscle mass, resistance training (RT) is considered the gold standard due to its effects on muscle protein turn-over which results in muscle hypertrophy in repetition maximum (RM) following a short period of time (4-10 weeks) (Leal et al., 2021). This anabolic effect of RT seems to match exactly the needs to counter-act the cachectic state induce by COVID-19 infection. In this regards the hypertrophic response to RT depends on proper manipulation of training variables such as the number of exercises, number of sets per exercise, repetitions, load, velocity of muscular action, frequency (number of sessions per week).

 

    The traditional ACSM recommendations to RT prescription to general population suggest that training should include 2-3 sets per exercise with intensity of 70% of 1 RM to induce the desirable adaptations (Garber et al., 2011). However, this positioning has been contested due to a broad data suggesting that muscle hypertrophy can occurs in a wide intensity spectrum, including low intensities (30-40% of 1RM) close to muscle failure or in a high effort situation. So, a variety of intensities can be used to induce training adaptations.

 

    Considering the possible physical limitations induced bypost-COVID-19 infection sets close to muscle failure cannot be well tolerated. In this regard, some data shows similar results with protocols 4-5 repetitions far from failure, which may be preferable for these patients (Silva et al., 2021). Regarding, to training load it seems that a minimum threshold level of resistance is required to induce hypertrophy (20% 1RM). Consequently, for a muscle gains purpose is reasonable to recommend protocols with at least 30% of 1 RM.

 

    Regarding the number of sets per exercise and weekly training volume the literature shows that multiple sets is superior to a single set to induce muscle hypertrophy (Silva et al., 2021). However, in the beginning of COVID-19 rehabilitation exercise tolerance can be reduced, particularly in patients with more severe complications. In this sense, even with inferior results, protocols with a single set can be adopted to induce positive training adaptations. As the tolerance to exercise increases the number of sets may be increased following the fitness level of the patient.

 

    In relation to training frequency, if training volume is equated the impacts of training frequency seems to be secondary (Krieger et al., 2010). Nevertheless, spread training session throughout the week can be more tolerated than a single session with a greater volume for patients with compromised physical function.

 

    Considering the importance of muscle strength, if the primary goal of training is to recover or induce strength adaptation the intensity should be increase progressively according to patient capacity as the intensity is the mains determinant of strength adaptation. This situation needs to be evaluated individually. (Hughes et al., 2018; Gibala et al., 2014)

 

    A recent study showed that short-term exercise rehabilitation program including, RT (2 sets, 10 repetitions, 30-80% 1RM), AT, balance and respiratory exercises showed clinically relevant improvements in functional outcomes in acute post-COVID 19 patients. (Udina et al., 2021)

 

    A previous recommendation for RT prescription for post COVID-19 infections suggest that multiarticular exercises including a lower number of repetitions, not led to failure and with longer rests between sets to minimize metabolic, respiratory and cardiac stress while maintaining the training efficacy should be utilized (Gentil et al., 2021). However, comparison between different exercises protocols and results about safety and efficacy still scarce.

 

    In regards to AT, their effects on muscle mass seems to be lower compared to RT. However, AE improve cardiorespiratory capacity and increase mitochondrial number and function. This adaptation can help to provide energy more efficiently to protein synthesis which is a high energy demanding process. Furthermore, the increase in capilarization and cardiac function may improve nutrient delivery to the muscle.

 

    In a cohort study of post-acute care patients that overcame COVID-19 and were included in a rehabilitation protocol based on multi-component therapeutic exercise (Udina et al., 2021). AT utilized was 15-minutes aerobic training with a cycle ergometer, step or walking. Intensity was 3 at 5 Borg scale modified utilized (Figure 2).

 

    AT may cause a more pronounced effect on muscle size if it’s realized with blood flow restriction. However, due vascular complication induced by COVID-19 infection the application of this protocol needs to be studded and possible adverse effects needs to be documented before a clear suggestion to an accurate prescription can be made.

 

    Then, RT protocols with single sets, progressing to multiple sets based on patient tolerance and capacity, with loads of 30-70% 1RM with the number of repetitions adjusted according to training load to induce some degree of effort with frequency of 2-3 sessions per week can be used to induce favorable adaptations. This model seems to fits post the phase 3-4 recommendations for COVID-19 returning to exercise (Figure 2) (Salman et al, 2021). AT should be implemented with progression based on patient tolerance, increasing gradually intensity and volume. However, as the cachectic state is characterized by a significant loss of muscle mass and physical function RE should be the main exercise type as a therapy.

 

Source: Author (2023)

 

    It is important to note that due to its recent it's not feasible to establish a strict clear recommendation how the protocols of RT should be structured to counter-act the cachectic state post COVID-19 infection and the majority of the recommendations of RE structure are based on general population and people with other diseases that may provoke muscle waste.

 

Future directions 

 

    In the future, what can be observed are new types of training that can lead to a better acute condition of muscle mass maintenance. A better identity of aerobic and resistance training is sought so that exercises can be better given to post-COVID-19 patients.

 

Conclusions 

 

    It is observed that the characteristic of reduced muscle mass after Sars-Cov-2 infection. Thus, cachexia is related to loss of functional capacity and other comorbidities associated with diseases. It is suggested a model of aerobic and resistance physical training that can alleviate or reverse sarcopenia and cachexia after COVID-19.

 

    Exercise plays a crucial role in the rehabilitation of individuals recovering from COVID-19, particularly in countering the muscle alterations induced by the catabolic effects of the virus. Both aerobic training (AT) and resistance training (RT) have been shown to be effective in increasing lean body mass, with RT considered the gold standard due to its ability to promote muscle hypertrophy. However, the intensity and volume of exercise should be tailored to the individual's physical capacity and tolerance, especially in the early stages of post-COVID-19 recovery. RT protocols with single sets, progressing to multiple sets, and using loads of 30-70% of one-repetition maximum (1RM) appear to be effective, while AT should also be included with gradual intensity and volume progression. Ultimately, exercise therapy, particularly resistance exercise, is crucial in addressing the muscle loss and physical function decline associated with post-COVID-19 cachexia.

 

References 

 

Asrani, P., & Hassan, M.I. (2021). SARS-CoV-2 mediated lung inflammatory responses in host: targeting the cytokine storm for therapeutic interventions. Molecular and Cellular Biochemistry, 476(2), 675-687. https://doi.org/10.1007/s11010-020-03935-z

 

Baethge, C., Goldbeck-Wood, S., & Mertens, S. (2019). SANRA—a scale for the quality assessment of narrative review articles. Res Integr Peer Rev, 4, 2-8. https://doi.org/10.1186/s41073-019-0064-8

 

Baracos, V.E., Martin, L., Korc, M., Guttridge, D.C., & Fearon, K.C.H. (2018). Cancer-associated cachexia. Nat Rev Dis Prim, 4, 17105. http://dx.doi.org/10.1038/nrdp.2017.105

 

Brandt, C., & Pedersen, B.K. (2010). The role of exercise-induced myokines in muscle homeostasis and the defense against chronic diseases. J Biomed Biotechnol., 20258. https://doi.org/10.1155/2010/520258

 

Briguglio, M., Pregliasco, F.E., Lombardi, G., Perazzo, P., & Banfi, G. (2020). The malnutritional status of the host as a virulence factor for new coronavirus SARS-CoV-2. Front Med (Lausanne), 7, 146. https://doi.org/10.3389/fmed.2020.00146

 

Chen, N., Zhou, M., & Dong, X. (2020). Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet, 395, 507-513. https://doi.org/10.1016/s0140-6736(20)30211-7

 

Cheval, B., Sieber, S., Maltagliati, S., Millet, GP, Formánek, T., Chalabaev, A., Cullati, S., & Boisgontier, MP (2021). Muscle strength is associated with COVID-19 hospitalization in adults 50 years of age and older. medRxiv. https://doi.org/10.1101/2021.02.02.21250909

 

Garber, C.E. et al. (2011). American College of Sports Medicine. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc, 43(7), 1334-59. https://doi.org/10.1249/mss.0b013e318213fefb

 

Gentil, P., Lira, CAB, Coswig, V., Barroso, WKS, Vitorino, PVO, Ramirez-Campillo, R., Martins, W., & Souza1, D. (2021). Practical Recommendations Relevant to the Use of Resistance Training for COVID-19 Survivors. Frontiers in Physiology, 12. https://doi.org/10.3389/fphys.2021.637590

 

Gibala, M.J., Gillen, J.B., & Percival, M.E. (2014). Physiological and health-related adaptations to low-volume interval training: Influences of nutrition and sex. 44(Suppl 2), S127-S137. https://doi.org/10.1007/s40279-014-0259-6

 

Gil, S., Jacob Filho, W., Shinjo, SK, Ferriolli, E., Busse, A.L., Avelino-Silva, TJ, Longobardi, I., Oliveira Júnior, GN, Swinton, P., Gualano, P., Roschel, H., & HCFMUSP COVID-19 Study Group (2021). Muscle Strength and Muscle Mass as Predictors of Hospital Length of Stay in Patients with Moderate to Severe COVID-19: A Prospective Observational Study. medRxiv. https://doi.org/10.1002/jcsm.12789

 

Gleeson, M., Bishop, N.C., Stensel, D.J., Lindley, M.R., Mastana, S.S., & Nimmo, M.A. (2011). The anti-inflammatory effects of exercise: mechanisms and implications for the prevention and treatment of disease. Nature reviews immunology, 11(9), 607-615. https://doi.org/10.1038/nri3041

 

Hughes, D.C., Ellefsen, S., & Baar, K. (2018). Adaptations to Endurance and Strength Training. Cold Spring Harb. Perspect Med, 8(6), a029769. https://doi.org/10.1101%2Fcshperspect.a029769

 

Jia, H. (2016). Pulmonary angiotensin-converting enzyme 2 (ACE2) and inflammatory lung disease. Shock, 46(3), 239-248. https://doi.org/10.1097/shk.0000000000000633

 

Jin, Y., Yang, H., & Ji, W., Wu, W., Chen, S., Zhang, W., & Duan, G. (2020). Virology, epidemiology, pathogenesis, and control of COVID-19. Viruses, 12, 372.

 

Krieger, J.W. (2010). Single vs. multiple sets of resistance exercise for muscle hypertrophy: a meta-analysis. The Journal of Strength & Conditioning Research, 24(4), 1150-1159. https://doi.org/10.1519/jsc.0b013e3181d4d436

 

Leal, L.G., Lopes, M.A., Peres, S.B., & Batista Jr, M.L. (2021). Exercise Training as Therapeutic Approach in Cancer Cachexia: A Review of Potential Anti-inflammatory Effect on Muscle Wasting. Frontiers in Physiology, 11, 1769. https://doi.org/10.3389/fphys.2020.570170

 

Li, T., Zhang, Y., Gong, C., Wang, J., Liu, B., Shi, L., & Duan, J. (2020). Prevalence of malnutrition and analysis of related factors in elderly patients with COVID- 19 in Wuhan, China. Eur J Clin Nutr, 74(6), 871-875. https://doi.org/10.1038/s41430-020-0642-3

 

Mehta, P., McAuley, D.F., Brown, M., Sanchez, E., Tattersall, R.S., Manson, J.J., & HLH Across Speciality Collaboration, UK (2020). COVID-19: consider cytokine storm syndromes and immunosuppression. The Lancet, 395(10229), 1033-1034. https://doi.org/10.1016/s0140-6736(20)30628-0

 

Pedersen, B.K., & Saltin, B. (2015). Exercise as medicine - evidence for prescribing exercise as therapy in 26 different chronic diseases. Scand J Med Sci Sports, 25(Suppl 3), 1-72. https://doi.org/10.1111/sms.12581

 

Queiroz Júnior, J.R.A., da Costa Pereira, J.P., Benjamim, R.A.C., Silva, N.O.L. da, Maria Eduarda de Paiva Silva, M.E. de P., & Ramiro, C.P.S.P. (2023). Relationship between sarcopenia and cachexia with prognostic markers of middle-aged and older inpatients with COVID-19: a case-control study. Eur Geriatr Med, 14(3), 217-526. https://doi.org/10.1007/s41999-023-00792-z

 

Salman, D., Vishnubala, D., Le Feuvre, P., Beaney, T., Korgaonkar, J., Majeed, A., & McGregor, AH (2021). Returning to physical activity after covid-19. BMJ, 372. https://doi.org/10.1136/bmj.m4721

 

Silva, A.B., Siqueira, S., Soares, WRA, Rangel, FS, Santos, NO, Freitas, AS, Silveira, PR, Tiwari, S., Alzahrani, KJ, Góes-Neto, A., Azevedo, V., Ghosh, P., & Barh, D. (2021). Long-COVID and Post-COVID Health Complications: An Up-to-Date Review on Clinical Conditions and Their Possible Molecular Mechanisms. Viruses, 13(4), 700. https://doi.org/10.3390/v13040700

 

Simpson, R.J., & Katsanis, E. (2020). The immunological case for staying active during the COVID-19 pandemic. Brain, behavior, and immunity, 87, 6-7. https://doi.org/10.1016/j.bbi.2020.04.041

 

Singh, S.K., & Singh, R. (2022). Cytokines and Chemokines in Cancer Cachexia and Its Long-Term Impact on COVID-19. Cells, 11, 579 https://doi.org/10.3390/cells11030579

 

Tieland, M., Trouwborst, I., & Clark, B.C. (2018). Skeletal muscle performance and ageing. Journal of cachexia, sarcopenia and muscle, 9(1), 3-19. https://doi.org/10.1002/jcsm.12238

 

Udina, C., Ars, J., Morandi, A., Vilaró, J., Cáceres, C., & Inzitari, M. (2021). Rehabilitation in Adult Post-COVID-19 Patients in Post-Acute Care with Therapeutic Exercise. The Journal of Frailty & Aging, 10(3), 297-300. https://doi.org/10.14283/jfa.2021.1

 

Virgens, I.P., Santana, N.M., Lima, S.C.V.C., & Fayh, A.P.T. (2020). Can COVID-19 be a risk for cachexia for patients during intensive care? Narrative review and nutritional recommendations. British Journal of Nutrition, 1-9. https://doi.org/10.1017%2FS0007114520004420

 

Welch, C. , Hassan-Smith, Z.K., Greig, C.A., Lord, J.M., & Jackson, T.A. (2018). Acute Sarcopenia Secondary to Hospitalisation - An Emerging Condition Affecting Older Adults. Aging Dis, 9(1), 151-164. https://doi.org/10.14336/ad.2017.0315

 

Welch, C., Greig, C.A., Masud, T., Wilson, D., & Jackson, T.A. (2020). COVID-19 and Acute Sarcopenia. Aging Dis., 11, 1345-1351. https://doi.org/10.14336/ad.2020.1014

Lecturas: Educación Física y Deportes, Vol. 28, Núm. 307, Dic. (2023)