An echocardiogram and the novel coronavirus.

The coronavirus responsible for the COVID-19 pandemic causes a illness that infects the upper and lower respiratory tract. In mild cases, symptoms include a cough and changes in the ability to smell and taste; in severe cases, it makes it hard to breathe and can cause pneumonia.

But it wasn’t long after the coronavirus started to spread around the globe that researchers identified a cascade of other effects, with the virus sometimes affecting organs in addition to the lungs, including the kidneys, brain, gastrointestinal system, and heart.

The potential effects on the heart may be of particular concern. Patients with pre-existing heart conditions are among the most likely to suffer from severe complications when infected with the coronavirus. And some reports of abnormalities and inflamed heart tissue in patients recovering from COVID-19—including patients who were asymptomatic or who experienced only mild symptoms—have caused alarm and led to frightening headlines about the long- term effects of the disease. 

“This particular virus seems to have a predilection for the myocardium or heart tissue,” says Tom Best, research director at the University of Miami’s UHealth Sports Performance and Wellness Institute and past president of the American College of Sports Medicine.

One fear is that the virus’s effects on the heart could increase the likelihood of developing myocarditis, an inflammation of the heart muscle that in severe cases can lead to heart failure and even cardiac arrest during intense physical activity.

Several athletes, including the Boston Red Sox pitcher Eduardo Rodriguez and the University of Houston defensive lineman Sedrick Williams, have had to withdraw from competition after doctors reportedly detected heart complications after they'd recovered from COVID-19.

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While there's good reason to be cautious while gradually resuming physical activity after recovering from COVID-19, some of the concerns and headlines could cause more panic than is warranted, says Euan Ashley, MD, a cardiologist and professor of medicine at Stanford University.

At Stanford, Ashley says, a surge in myocarditis that needs treatment hasn't emerged—at least yet. While some early research suggests that the virus may affect the heart in ways that can be detected on scans, for example, there’s no indication that COVID-19 is causing widespread heart problems.

Consumer Reports spoke with cardiology and sports medicine experts to understand exactly what doctors have learned about how the coronavirus affects the heart, and what people should know about returning to physical activity after getting over COVID-19. 

Heart Abnormalities

Though scientists have known since early on that acute infection with the coronavirus can affect the heart, several recent studies helped kick off a wave of concern about what the coronavirus might be doing to the hearts of people who experienced only mild infections.

For example, a July study in JAMA Cardiology looked at MRI scans of 100 people from Germany who had recovered from COVID-19 and found some kind of heart abnormality in 78 of them, including some who had been hospitalized and others who had not. And in the September issue of JAMA Cardiology, researchers reported finding heart abnormalities consistent with myocarditis in four of 26 Ohio State college athletes who had tested positive for COVID-19, including two with mild symptoms and two who were asymptomatic. 

Initially, these might appear to be surprisingly high levels of ongoing heart issues. But they are perhaps less alarming than they seem, according to Eugene Chung, chair of the American College of Cardiology’s Sports and Exercise Cardiology Council.

For example, in the case of the Ohio State athletes, Chung says, it's unknown if COVID-19 caused the heart inflammation and abnormalities, or if many or most of those problems existed before the infection but had not been detected. 

And in the case of the German patients, the heart abnormalities found could illustrate how viruses in general affect the heart. Many other viruses—such as those that cause the flu or the common cold—can also inflame the heart, Chung says. Researchers haven't looked for myocarditis or other heart abnormalities in people recovering from these other respiratory infections, but it’s possible that they occur with similar frequency after the flu, he says. Scientists would need more research to be sure.

Ashley, from Stanford, agrees. “The scale of the pandemic is by definition massive; the focus on the disease is enormous,” he says. But the effects on the body aren’t unexpected. “The virus behaves very classically as we’d expect.”

Finding some sort of effect on the heart in a number of people recovering from the coronavirus may also simply be a result of the flurry of research on people infected with COVID-19. “You can find abnormalities when you look in many people,” Ashley says.

In rare cases, some abnormalities might indicate myocarditis, but scientists will need more data to see how many people suffer any lasting impairment. Many of these abnormalities wouldn't be noticeable without a scan that went looking for them, and in most cases these minor abnormalities can resolve over time. People who do notice symptoms, like heart palpitations or chest pain, should talk to their doctor.

While scientists are still learning how often COVID-19 affects the heart, it's reasonable for people recovering from the disease to consider the risk and talk with their doctor about any concerns or heart-related symptoms they experience as they recuperate, Best says. 

Resuming Physical Activity

While scientists are still learning how often COVID-19 affects the heart, it's reasonable for people recovering from the disease to consider the risk and talk with their doctor about any concerns or symptoms they experience as they recuperate, Best says. 

As news about the potential effects of the coronavirus on the heart have spread, one of the major fears that people recovering from COVID-19 may have is whether, and when, it's safe to exercise again. 

Because the coronavirus is so widespread, affecting people of different ages and health statuses, and with effects that can range from undetectable to life-threatening, the exact right plan for a return to exercise is going to vary, Best says.

Currently, the American College of Sports Medicine recommends that any individual who had COVID-19 consult with their doctor to determine the safest way to exercise. That's especially important for people who are severely ill, older, or have other health conditions, as well as those who had moderate or more severe coronavirus symptoms, Chung says.

If a doctor does discover myocarditis, he or she might recommend three to six months of rest.

But most people, especially those who started healthy and had less severe infections, should be able to resume activity much sooner. After getting over the flu, doctors often recommend resting for 10 to 14 days before engaging in high intensity exercise, and people should rest at least a similar amount of time after a case of COVID-19, Chung says.

People who had just mild symptoms and were in good health before getting sick should be able to slowly resume activity after this time, gradually ramping up activity, he says. He recommends the same for people who had likely cases of COVID-19 but were never tested.

Take it slow, according to Best. Start at half your previous pace or intensity, and ramp it up by about 10 percent a week, he says. He also recommends including strength training in your regimen, because it’s been shown to be particularly helpful for people recovering from heart issues.

As people are getting active again, potential red flags for any sort of heart trouble include chest pain, difficulty breathing beyond that you’d normally expect with exercise, heart palpitations, and lightheadedness, Ashley says. If you experience any of those symptoms, stop exercising and consult your doctor on next steps.

Even modest amounts of exercise can significantly improve health, and being inactive too long harms both physical and mental health, Best says. “Physical activity is probably the best medicine we can prescribe,” he says—and that’s probably true even for people who have had COVID-19.

Doctors have learned a lot about the virus over the past months, Best says, but they still have far more to discover. “In six months or a year we may have more specific guidelines,” he says.