Yes, I am. I was a long distance runner, also called ultra runner. 100 km and more.
But on the other hand, perhaps interesting: The story of Dr. Godfrey. You can find it at:
edubily.de/2016/11/wie-kranke-herzen-heilen-koennten/
The article is unfortunately in german. But the references and studies are in english.
I did HIIT and the damaged part of my heart muscle begins working again. Of course, you should never try it without your physician.