4 1/3 Miles (or 13 laps).
The last lap wasn't especially peppy, but I tried to up my pace just a little, to prove that I could. Upon returning home, and after stretching, I took a dose of my own medicine and let my feet and ankles rest in some ice water, put an ice pack on the back of my left knee, plus did some extra calf stretches. Nothing hurt during the run, but I could feel the sole of my right foot, and both my calves, working a little extra hard.
Here's a tip that I read once, and has been reiterated by what little research I've done on yoga: lie on your back with your legs up in the air for 10 minutes every evening. It was allegedly done by members of some posh ballet company. (Is there really a way to have unposh ballet?) Reversing gravity on your legs enables passive fluid drainage (both blood and lymph) to prevent swelling and give your veins a break. It's an easy habit to maintain; I like to read before I go to bed, so while I'm kicking back with my book, I just happen to kick my feet up the wall.