I posted in mileage & have a blog that documents my slow build. I made a mistake the week before the calf injury/incident. I have also been down this road before. I lowered my run times from 55/55/65 down to 35 mins (stopped after calf pain), waited 3 days when pain was gone & was only able to go for 29 mins. In my experience, these drops are a sign of growing potential for injury. So i'm trying to up the cross training (especially ones that strengthen my legs/core like the 100 ups challenge), swim, & do yoga & keep my fingers crossed. Since waiting for the pain is not a good indicator, I am going to wait at least a week, then lower down to 25 mins & wait 3 days between runs (at a very slow pace) to make sure the calf pain is abating. Any other advice from my BF peepe? Tx! s/s.