You're assuming EKG is definitive. I had an EKG last week, the analysis comes back "borderline". Running down every abnormality listed (I know my cardiologist

You're assuming EKG is definitive. I had an EKG last week, the analysis comes back "borderline". Running down every abnormality listed (I know my cardiologist has seen it, didn't consider it notable) has a range of possible causes, including the changes that come with good endurance.