Training with Covid or not – that’s the question some fitness fans ask. The American College of Sports Medicine has suggested people under 50 who experience mild or no symptoms rest for at least seven to 10 days after testing positive. Their recommendation seems to be motivated by the concern that even a mild Covid-19 infection can damage the heart and potentially cause sudden death during physical exertion.
There is little evidence to support this recommendation. Because exercise boosts the immune system, it can even help people get back from Covid faster.
Viral infections, including those that cause flu and colds, are a major cause of myocarditis, inflammation of the heart muscle. The condition can cause chest pain and irregular heartbeat, although it is often asymptomatic. This makes its prevalence difficult to measure. According to some estimates, 1% to 5% of all people with acute viral infections can develop myocarditis.
Yet sudden death from myocarditis during physical activity appears to be rare. A study from 1980 to 2006 documented 41 sudden deaths in young athletes (under the age of 40) associated with myocarditis – one tenth as many as from blunt trauma.
Some experts feared that Covid-19 would increase the risk of heart disease in otherwise young and healthy people. A study early in the pandemic from Germany reported signs of myocarditis in 60% of Covid-19 patients, including some with relatively mild illness. But criticism of the study’s design and data errors led to more studies, and recent studies have mostly been reassuring.
In one study, heart tests were performed on 789 professional athletes (football, baseball, basketball, soccer, and hockey) with previous infections, most of whom had mild or no Covid symptoms. Only five (0.6%) had inflammation of myocardial infarction – consistent with estimates of other viral infections – and all had symptoms that researchers said “exceeded empirical definitions of mild COVID-19 disease” such as cough, fatigue or loss of taste.
In another study, only 0.7% of 3,018 college athletes tested positive for Covid had abnormal heart test results that researchers thought were certain, likely, or possibly associated with the virus. (Extremely healthy athletes are known to have “rebuilt” hearts that can cause abnormal findings on heart tests. This makes it difficult for cardiologists to tell if the abnormalities are due to the virus.)
A third study involving 3,597 college athletes who had tested positive with symptoms ranging from none to chest pain and short width showed that only 1.2% experienced symptoms that lasted for more than three weeks. Only 4% experienced heart or lung-related symptoms when they returned to exercise. Yet the vast majority of those who underwent multiple tests showed no signs of heart damage from Covid-19, and it is normal to experience fatigue or shortness of breath when returning to exercise after a flu-like illness.
Surveys of young competitive athletes are easier to perform than on the general population, and they may not be 100% useful for recreational athletes. Still, they show that otherwise healthy and fit people receiving Covid are unlikely to suffer from heart complications.
A recent study by UK health workers showed that those who had mild or no Covid symptoms were no more likely to have heart abnormalities on test six months after infection than those who had not been infected. “This study shows that in healthy people, measured cardiovascular abnormalities are common but not more common in those who had had mild SARS-CoV-2 6 months earlier compared to those who did not,” the researchers found.
The seven- to 10-day rest recommendation seems to be as arbitrary as the six-foot social distance from early in the pandemic. Most people who do not know they have Covid will not follow it anyway.
“There is very little good quality data on the resumption of training after Covid,” said Gabriel Vorobiof, a cardiologist at UCLA, in an email. “At one point, there was a lot of controversy when a few cardiac MRI papers showed some potential regarding heart findings after Covid.” However, as the studies did not include a control group for comparison – such as athletes or young people without Covid receiving an MRI – he says that “the findings were later rejected as associations, not necessarily causal relationships.”
He adds: “I have seen quite a few young athletes who have demanded ‘heart approval’ from their sports club after having uncomplicated Covid before resuming their respective sports, many of which were non-competitive. The need to cleanse a young person after an asymptomatic viral disease, like many things during this pandemic, seems to be an overreaction based on little if any science. “
Doctors generally advise people with colds to exercise, but should listen to their body. This seems like sensible advice to otherwise healthy people with mild Covid. “However, if symptoms of chest pain or discomfort, dizziness or palpitations occur, one should stop and seek medical attention,” says Dr. Vorobiof.
Exercise has been shown to protect people from other viral infections, including influenza, herpes, Epstein-Barr and the common cold, and to improve the immune response to vaccinations. Each workout mobilizes billions of immune cells, especially the T cells that circulate, identify, and kill virus-infected cells. Exercise also reduces the level of the stress hormone cortisol, which degrades the white blood cells and increases inflammation.
While people are learning to live with Covid, there is no reason why they should not also practice with it.
Ms. Finley is a member of the magazine’s editorial board.
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