I am not back at my previous best, but that is in part to having a decade off. I was never that fast anyway: 18, 36-high, 82/83 etc as a young master, age: 40-42.
I am now 55 and have been back running nearly four years, had the surgery nearly five years ago.
One issue was recurring calf pulls, but I may be past that now. So, I wasn’t able to do more than 30-50 miles per week. Also, fast stuff would trigger pulls.
So, I am around 22:20, 46, who knows for the half….