How could it be...

For starters I would like to say my period os never late, I usually get it within the first few hours if my first predicted day. But now for this cycle I’m pushing to be 4 days late. Could there be any reason of it being late besides pregnancy. I had just stared track before the big worry about the pandemic and I’ve been doing high intensity training since the season started 2 weeks ago could that be why? Help!