MEDFORD, Ore. — Even healthy, athletic people who have recently had a mild or moderate case of coronavirus can develop heart issues if they try returning to vigorous exercise too quickly, Providence Medical Center said on Tuesday.

Healthcare providers have grown increasingly concerned about cardiac issues arising among people who have had COVID-19 and don't take it easy for several weeks.

"Researchers and physicians now recommend waiting at least 10 days after the end of symptoms to begin a slow return to exercising," Providence said.

Providence Sports Medicine recommends that patients who have had COVID-19 start out with 10 to 15 minutes of slower-paced activity, keeping heart rates at specific targets with the help of a medical providers. Activity intensity and duration can increase over time. You should stop exercising immediately if you experience chest pain or shortness of breath.

"Depending on patients’ pre-COVID fitness level and the severity of their COVID infection, it can take several weeks to several months to return to their earlier fitness level," Providence said.

Some research has shown that about 7 percent of patients with a mild or moderate case of COVID-19 who were not hospitalized can still develop some kind of cardiac problem. Exercising too rigorously post-COVID can cause long-term damage to the heart, even in a moderate case.

COVID-19 can cause myocarditis, leading to inflammation and long-term scarring or weakening of the heart. If this happens, Providence recommends avoiding exercise for three to six months. Arrhythmia is another risk, and can be fatal for former COVID patients who try to push through feelings of fatigue with vigorous activity.

For active people who had moderate symptoms of COVID-19 — particularly those who exercise regularly and put a high premium on their health through training, competition, or sports — it may make sense to consult with a healthcare provider before returning to a normal level of activity.

Screening can be recommended based on age, risk factors, or severity of COVID symptoms. Tests may include an EKG, labs, or ultrasound of the heart to evaluate the person's health before clearing them to start gradually stepping up activity.

"More studies are needed to understand how this virus and other viruses can affect exercise and heart function," Providence said. "There’s so much we don’t know yet with this new, devastating disease. But it’s becoming clearer every day that there are potential cardiac effects in some patients, and we should be careful and conservative in supporting their return to an active life."