I went to the track and did HIIT earlier tonight. Since I ran a bit yesterday, my shins wore out like economic girly men. I managed to complete a mile before I needed to rest my feet, but I wasn't out of breath, which is a good sign. On the first two laps the high intervals were more runs than sprints, but I went all out on the last two. I'm as fast as ever, except with an improved stride from all the stretching I'm doing (which I did for thirty minutes beforehand).
Now, my shin hurts like hell because afterward I practiced kicking a tree. I also punched it, but it didn't hit me back or anything. Pussy.