Exercise as a Mechanism to Combat COVID-19 Related Cardiovascular Problems
By: David Marocco
Symptoms and infection of COVID-19 virus have been observed to vary among carrier patients. While a majority of cases possess short term symptoms such as loss of taste, congestion, fatigue, etc, COVID-19 can cause long lasting symptoms beyond the infectious period. This is clinically known as post-COVID-syndrome (PCS). PCS can lead to cardiovascular complications, especially in individuals with pre-existing heart issues. Exercise is a well known combatant of cardiovascular disease and can be used to minimize the degree of the symptoms. Exercise also has the ability to prevent COVID-19 symptoms as a whole by strengthening the cardiovascular and immune system.
In December of 2019, the COVID-19 pandemic, also known as SARS CoV-2, took the world by storm and began infecting millions of people. COVID-19 is a highly transmissible disease that infects the respiratory system with the ability to affect other major systems of the body.1 Those who have been infected severely enough suffer long lasting symptoms, a phenomenon called post-COVID-syndrome. Depending on the severity of infection and the individual, long lasting effects vary from loss of taste and smell to chronic fatigue and headaches. There has also been a reported impact on the cardiovascular system of those who suffer from post-COVID-syndrome, including chest tightness, palpitations, syncope, dysautonomia, hypotension and other heart related illnesses.2 While treatment for select issues is available, research shows that those involved in daily physical exercise reduce their likelihood of developing cardiovascular issues when infected with COVID-19, as well as reduce the severity of their symptoms if they do occur.2
According to the United Kingdom National Health Service, post-COVID-syndrome (PCS) is defined as “unexplained, persisting signs or symptoms over 12 weeks, developed during or after the COVID-19 infection.”2 The symptoms for post-COVID-syndrome are numerous and wide-ranging. Studies have shown that people with PCS continue to suffer from a multitude of ailments including severe body ashes, migraines, and chronic fatigue even months after being infected.3 An online survey reported more than 200 lasting symptoms among people who have experienced PCS.2
Post-COVID syndrome is a relatively common occurrence. A study that began in April 2020 by the UK’s Office for National Statistics showed that 13.7% of people who tested positive for COVID-19 between April 26, 2020 and March 6, 2021 continued to show symptoms after 12 weeks.2 This signifies that although most people overcome the effects of COVID-19, a significant number of people do not. The numbers are staggering when considering those who were hospitalized with COVID. A revealing study indicated that up to 87% of people who were once hospitalized with COVID-19 show long lasting symptoms.4
When a metal implant is placed within a bone, it must first be stabilized by the bone itself and proceed with osseointegration5, which is when the bone tissue fuses onto the metal implant anchoring it into the original bone, another term for this phenomenon is “biological fixation.”6 However, when the bone is osteoporotic, there is a 25% bone mass decrease and its regeneration7 and osseointegration abilities plummet.8 This results in a major increase in marrow space which makes the bone fragile and it is no longer strong enough to support a metal implant.7 Unfortunately, fracture reconstructive habilitation has become a great challenge for surgeons.9
Unfortunately, there are many questions yet to be answered regarding this condition regarding the causes and possible treatments. Medical professionals are still trying to determine its cause and why matters such as severity of infection do not directly correlate to the severity of the syndrome. For example, non-hospitalized COVID victims have reported lasting effects. In a study published in September 2021 on non-hospitalized COVID-19 victims, 30% reported fatigue and 37% reported cognitive impairment after infection.4 Post-COVID-syndrome has also been shown to be a severe risk on those with cardiovascular issues and has the ability to cause the development of heart conditions as well.
In order to fight infection, the immune system must act quickly in order to minimize both direct and indirect damage to the heart. The beginning stage of myocarditis begins with viral replication and direct damage to the muscular tissue of the heart. When this occurs, the virus is recognized by host factors called pattern recognition receptors (PRRs). These factors stimulate the production of antiviral proteins that initiate the immune response and heart tissue repair. Firstly, the innate immune system attacks with neutrophils, natural killer cells and macrophages. This is followed later on by the response of the adaptive immune system. The second stage of myocarditis consists of immune-mediated damage. This happens as a result of “cardio modulatory cytokines by immune cells, from the release of cytotoxic molecules that damage healthy cells, or from the presence of cardiac autoantibodies.”5 Depending on the severity of infection as well as the individual, the disease may be resolved or continue into a more severe, chronic phase.
COVID-19 and Myocardial Infarction
COVID-19 has the ability to disrupt functions of the body. Among the functions interrupted, the cardiovascular system stands out because of COVID-19’s harmful effects. Firstly, it is important to understand how COVID-19 accesses the cells. The ACE2 protein is a cardioprotective transmembrane protein which is found in great amounts in the myocardial tissue. The COVID-19 virus attaches to the ACE2 receptor to gain access to the cell, and downregulates its expression.6 A study performed on mice infected with the human strain of SARS-CoV was conducted to examine ACE2 protein expression in the hearts of those infected. The study found that the presence of SARS-CoV in the heart was associated with the reduction of ACE2 protein expression.7
Due to COVID-19’s ability to attack the heart, many people continue to suffer from COVID-related heart issues. This has the ability to complicate pre-existing diseases and oftentimes can worsen them. Patients with Congestive Heart Failure (CHF) are particularly vulnerable to complications. CHF occurs when the heart cannot properly pump blood to the body due to weaknesses in the heart muscle.8 In some cases, there is an excess pooling of blood in certain parts of the body such as the legs, belly or even the lungs.9 As of 2017, approximately 5.7 million people in the United States were reported to have CHF with estimates of the US reaching 8 million by 2030.8 There is no singular cause for CHF, but those who smoke and drink regularly, or do not maintain a healthy diet and weight are more likely to develop CHF.9
With regard to COVID-19 and CHF, mortality rates and hospitalization time for people with both were observed to be higher than those without CHF. During a study conducted in 2021 at Mount Sinai Hospital systems in New York, a total of 6,439 patients were admitted to the hospital due to COVID-19, 422 of them with a history of CHF. Compared to the COVID-19 patients without a history of CHF, those with a history had higher systolic blood pressure and lower oxygen saturation. They also were at a greater risk for mechanical ventilation and on average spent two more days in the hospital than those without a history of CHF.10 This indicates that COVID-19 has the ability to complicate pre-existing heart conditions and put some people at a greater risk of developing lasting effects.
COVID-19 has the ability to attack the heart, causing or contributing to heart related problems. But the effects of COVID-19 are not just related to CHF. There is also a direct relationship between people with cardiac diseases and mortality and morbidity (2). In order to avoid these issues, it is very important for people to put themselves out of risk of heart related diseases. While screening for diseases is a start, it may come too late in certain cases. A well studied aid to preventing heart disease, however, is exercise. Unlike screening, exercise can never come too late and has immediate benefits. Exercise can protect against cardiovascular disease as well as the effects of COVID-19.
Exercise Improves Cardiovascular Health
One of the most universally accepted ideas is that exercise has tremendous health benefits and can improve many aspects of physical health, including the cardiovascular system (Figure 1). Numerous studies have shown that daily physical exercise contributes to a healthier heart.2 However, even with the evidence from these studies, many people are unable to start doing such exercise. According to the Center for Disease Control and Prevention (CDC), less than 25% of the adult population in the United States perform daily exercise.2 This means that people are putting themselves at a higher risk of cardiovascular issues because they are not strengthening their heart, regardless of whether or not they contract COVID-19. If they do contract the disease, there is an even higher risk of developing issues because they might have a weaker cardiovascular system due to their physical inactivity .
Figure 1. Possible beneficial outcomes of exercising on common post-COVID-19 syndrome symptoms. (Adapted from reference 2)
The cardiovascular system is greatly improved by physical exercise. When blood travels through the body, it releases oxygen that is needed for our body to function. Cardiovascular exercise improves the heart’s ability to pump the blood around and thereby supply oxygen to the rest of our body. When one runs, the body requires more energy in order to move, so the heart must work harder and blood is more quickly pumped through the body. If blood is flowing through the body more quickly, then supply of oxygen to the muscles increases, improving their abilities.11 Exercise trains the body to pump blood faster and increase production and efficiency.
Those with CHF also have a reported lower peak oxygen consumption (V02 Max). Peak oxygen consumption is defined as the “product of cardiac output (CO) and arteriovenous oxygen (AVO2) difference.”11 They are not receiving adequate oxygen amounts, and their hearts are not functioning totally properly as a result of the lower oxygen levels caused by the heart disease. Exercise can improve the V02 max though. In a study consisting of over 2,102 individuals aged 60 and older, aerobic exercise, or “cardio”, caused a 16.3% increase in peak oxygen consumption.11 V02 max is important because it is an indicator of how well an individual's heart is pushing blood around the body.11 Therefore, one with a higher peak oxygen consumption has a higher functioning heart.
Many other clinical trials have shown that moderate daily exercise can improve the cardiovascular system. A study conducted over a 4 month period was done in order to determine the effects of inputting exercise in the daily routine of individuals who have metabolic syndrome. Metabolic syndrome is defined as a cluster of conditions that increases the risk of heart disease.11 The study reported that after the 4 months, the individuals “had reduced adiposity, decreased systolic, diastolic and mean arterial blood pressure, and lower total and low-density lipoprotein (LDL) cholesterol lipid profiles compared to the control group.”11 Participants of the study were found to be at a lesser risk for heart disease due to physical activity.
Obesity is another factor that can increase the risk of heart disease. Obese individuals require more blood to supply their bodies with oxygen. This results in an increase in blood pressure as the body works harder to move more blood around the body.11 Exercise decreases body fat, lowering the risk of heart diseases. Even walking a certain amount of distance per day can significantly increase cardiorespiratory fitness in obese individuals and ultimately lower the risk of cardiovascular disease.11
Exercise even has benefits for individuals who have already been diagnosed with a disease. Even though they can no longer prevent the disease from occurring, it does not mean exercise will not improve their health. Exercise can be used as a therapeutic treatment in those who have cardiovascular disease and can significantly decrease mortality rate amongst these people while having the ability to improve their conditions.12 An example of this can be found in patients with CHF who performed 4 weeks of high intensity interval training (HIIT). The results of the study showed that these individuals had an improved peak oxygen consumption and reduced diastolic dysfunction.11
There is also a direct correlation between exercise and the immunological response. Factors such as intensity and frequency of exercise have impacts as well. For example, muscle contraction promotes the release of both pro and antiinflammatory cytokines at levels that vary based on intensity and duration of the movement (Figure 1).13 The release of cytokines recruit neutrophils to the site, which engulf and destroy infecting pathogens. Physical activity also increases the concentration of leukocytes circulating in the blood. This concentration remains at its peak 30-120 minutes after exercise and can persist for almost 24 hours.13
The further section discusses these biological processes at a more biochemical level.
Evidently, COVID-19 can cause complications in the cardiovascular system and lead to worsening symptoms of post-COVID-syndrome. Therefore, it is important for people to exercise to improve their cardiovascular health, as well as boost their immune response to infection. Exercise can prevent heart related issues, making it important for people to exercise so that COVID-19 will have a limited effect on cardiovascular diseases. For individuals already suffering from heart disease, it is important for them to exercise as a mechanism to improve their state of health. This will reduce the likelihood of post-COVID-syndrome.
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Visco, Valeria, et al. “Post-Covid-19 Syndrome: Involvement and Interactions between Respiratory, Cardiovascular and Nervous Systems.” Journal of Clinical Medicine, vol. 11, no. 3, 2022, p. 524., https://doi.org/10.3390/jcm11030524.
Oudit, G. Y., et al. “SARS-Coronavirus Modulation of Myocardial ACE2 Expression and Inflammation in Patients with SARS.” European Journal of Clinical Investigation, vol. 39, no. 7, 2009, pp. 618–625., https://doi.org/10.1111/j.1365-2362.2009.02153.x.
Savarese, Gianluigi, and Lars H Lund. “Global Public Health Burden of Heart Failure.” Cardiac Failure Review, vol. 03, no. 01, 2017, p. 7., https://doi.org/10.15420/cfr.2016:25:2.
Baman, Jayson R, and Faraz S Ahmad. “Heart Failure.” Jama Network, https://jamanetwork.com/journals/jama/fullarticle/2769187.
Standl, Eberhard, and Oliver Schnell. “Heart Failure Outcomes and Covid-19.” Diabetes Research and Clinical Practice, vol. 175, 2021, p. 108794., https://doi.org/10.1016/j.diabres.2021.108794.
Fleg, Jerome L. “Exercise Therapy for Older Heart Failure Patients.” Heart Failure Clinics, vol. 13, no. 3, 2017, pp. 607–617., https://doi.org/10.1016/j.hfc.2017.02.012.
Pinckard, Kelsey, et al. “Effects of Exercise to Improve Cardiovascular Health.” Frontiers in Cardiovascular Medicine, vol. 6, 2019, https://doi.org/10.3389/fcvm.2019.00069.
da Silveira, Matheus Pelinski et al. “Physical exercise as a tool to help the immune system against COVID-19: an integrative review of the current literature.” Clinical and experimental medicine vol. 21,1 (2021): 15-28. doi:10.1007/s10238-020-00650-3