Physical fitness improves our chances of survival in any strenuous response to a threat to life.
Don't have a percentage to quantify it though. Not sure anyone else does, either.
Recently,when I was checking into a hotel in Nevada where I was teaching a class, the nice young lady at the desk told me where the workout room was. I said, "Good to know." She replied that it was great that someone my age worked out.
I answered, "Nah, it's just that if my significant other gets mad at me, I need to know the one place in this hotel where I can hide from her, and she'll NEVER think to look for me there."
In other words, I respectfully suggest that you do as I say and not as I do...