This can happen even if you have no symptoms at all. In a recent study published in JAMA Cardiology, German researchers performed cardiac MRI testing on 100 adults who had recovered from COVID-19. About half of them had mild to moderate symptoms and 18 percent never had any symptoms. Though the testing was performed two to three months after their diagnosis and none of them had experienced heart symptoms related to the new coronavirus, 78 of them had structural changes to their hearts, and 60 had myocarditis.

Ironically, athletes might be at particular risk for this complication because intense activity during active infection—even if you’re showing no symptoms—may cause the virus to replicate at a faster rate, Makadia says.

“During training, you increase your cardiac output. If you’re infected, this could in theory increase the viral replication in the heart muscle. If that happens the higher viral load may increase your risk of cardiac harm in the form of myocarditis, arrhythmias, and heart failure,” he says.