Earlier quoted context omitted.
If you're completely out of shape, going at HIIT level intensity is also risky. Better to build some kind of baseline before jumping into the deep end.
It is not risky but it is hard and I rather do low intensity running 60 minutes than 8 minutes HIIT.
EDIT:: added my experience
I was riding mountain bike, and went to competition here and there. And then I stopped for many months, got back and rode the same speed. For real I thought I was going to die, it was almost a black out and panic. Never again risking with "coming back with intensive training" .. just no.