When coronavirus first emerged, medical experts quickly realized how fast it could attack the lungs. As we continue to live with the virus, researchers are increasingly learning how it can affect the heart – even the hearts of the youngest and strongest.
In late summer, there was an influx of reports suggesting the hearts of the young, physical elite, like college and professional athletes, were experiencing the toll of Covid-19. In August, ESPN reported that at least five Big Ten conference players had had signs of myocarditis – an inflammation of the heart. By early September a widely circulated study on 26 Ohio State athletes who had recovered from Covid-19 found that four had signs of myocarditis.
There are still lots of unknowns when it comes to how Covid-19 affects the heart, especially young healthy hearts, explains Saurabh Rajpal the first author of the study on Ohio State's athletes. His study didn't have a control group, so it can't prove that Covid-19 was causing these problems in athletes, Rajpal cautions.
"There is what we call circumstantial evidence," he tells Inverse.
At this point, we do know that Covid-19 has an "affinity" for the heart, adds Jonathan Drezner, the director of the University of Washington Medicine Center for Sports Cardiology.
"The extent this occurs in young healthy persons with mild or asymptomatic infections is still unknown," he tells Inverse.
In the meantime, scientists are poring over data extracted from college and professional athletes in an effort to gain a clearer picture of what the connection between myocarditis and Covid-19 really is — and how a heart that's eager to get pumping can get back into the swing of things.
And as the science develops, there's one lesson for people wondering how to work out after coronavirus, says Matthew Martinez, former chair of the American College of Cardiology's Sports and Exercise Council and the lead cardiologist for Major League Soccer:
Take ten to 14 days completely off, then start slow.
"I'm not saying that you have to become a couch potato for those 10 days, but this is not the opportunity to go out and see how that five-mile run feels," Martinez tells Inverse.
How does Covid-19 affect the heart?
It's not uncommon to see swelling in the heart caused by a viral infection, Martinez explains. What is uncommon, however, is how often this is swelling is seen among Covid-19 patients. Originally, this was observed in about 25 percent of older, hospitalized patients, he estimates.
"Then we started to see it in younger patients too," he tells Inverse. These were patients who were as young as 18 and those in their early 20s.
That development led cardiologists to recommend that athletes take off two weeks after testing positive for coronavirus, even they were asymptomatic.
Still, there's no overwhelming evidence proving the virus itself infected heart cells and caused these changes to the heart, adds Martinez. A roundup of 39 autopsies published in July found that the virus had infected heart cells in 24 cases, but provided no evidence that it was associated with an influx of inflammatory cells that might suggest a case of myocarditis.
Rather, scientists are seeing trails of evidence suggesting that the heart may be under duress.
In some cases, scientists are seeing markers of injury in older, hospitalized patients with Covid-19, specifically high levels of troponin. Troponin is a protein found in the heart muscle that, when found free-floating in the blood, is sometimes used as a sign of cardiac injury.
A September JAMA report on college athletes, however, didn't find evidence of higher troponin levels. Instead, it documented swelling and possible injury to heart cells in four athletes. There were other signs of cell injury in an additional eight patients who didn't meet the criteria for myocarditis, but those patients had no swelling.
Another puzzle, Martinez adds, is that he hasn't seen much scar tissue in young people's hearts. Scaring can happen as a result of myocarditis and lead to a weakening of the heart — there are examples of scarring on the hearts of older patients, from anecdotes and autopsies.
The takeaway, for now, says Martinez is that we still don't know enough about how Covid-19 affects young hearts. There are early indicators that something may be awry, but still not enough to categorize it fully. The majority of infections, he says, don't seem to cause significant damage to the heart.
"You see scattered reports, but usually they get top billing," he says of the reports from the late summer. "If you've got 700 athletes in a place like Ohio State and four of them have cardiac involvement that's a different discussion than if four of them of the 26 [have cardiac involvement]."
But the threat of heart damage is real enough to keep researchers moving. Martinez is currently one of a team of scientists monitoring data from NCAA, Major League Soccer, the WNBA, the NBA, and the NFL, looking for signs of heart complications among athletes in their 20s and 30s.
"We haven't had anybody collapse in the field; we haven't had any sudden death," says Martinez. That's not to say this hasn't happened elsewhere: In Serbia, former Florida State center Michael Ojo did collapse on the court in August and died. He had tested positive for Covid-19, but had seemingly recovered, CBS reported.
"I'm literally knocking on wood right now," says Martinez.
Can you exercise with coronavirus?
You don't have to be an athlete to find the developing connection between heart injury and coronavirus concerning, Rajpal says.
"There are a lot of people who are not competitive athletes are also doing pretty strenuous exercise," he says.
No matter what kind of exerciser you are, he recommends taking two weeks off after testing positive even if you are asymptomatic. Both Drezer and Martinez suggest that there some situations in which it might be worth seeking a second opinion before diving into a workout.
If you're a regular exerciser who feels that workouts post coronavirus are feeling significantly different, it might be worth consulting a cardiologist, Drezner says. Taking into account that you may have lost a bit of conditioning after taking time off to recover, he says that these signs might suggest it's time to talk to a doctor:
- Feeling outsized chest pain
- Reduced tolerance for exercise
- Shortness of breath that's disproportionate to the workout
Martinez also recommends consulting a doctor if you've had Covid-19, or have other pre-existing conditions, and are looking to get into exercise for the first time.
Even with the go-ahead to work out, and two weeks of rest completed, Martinez says to take it slow, and phase back in gradually. Even if you're feeling spry and eager to go, there are too many unknowns to push a post-coronavirus workout right out of the gate.