It's worth pointing this stuff out and it is very interesting, though it should not be taken as advice not to exercise. Most of us are a million miles away from being "elite" athletes. I run and bike regularly, but by no means am I an athlete!!
I'm not sure "intense" is the right word to use. I think running for 60 seconds at maximum intensity is unlikely to have any negative effects on your heart unless have ischaemic or valvular disease or you have never run before in your life!
Mark