Slowly Getting Faster

The smog finally cleared and I was able to hit the road today.  I thought I should break back into the week with an easy effort so I ran at a pace that felt comfortable and didn't check my watch until mile 3.  When I did finally check my watch it said I had been running 8:15 per mile. Before the smog set in, this same course at an easy pace usually worked out to around 8:30-8:40 per mile. There are a couple of reasons that this could have been faster today. 1) I was rested because I couldn't get out monday or tuesday, or 2) the speed work I've been doing on the treadmill has been paying off. I hope it's the latter.  We'll see how the rest of the week works out.  I did notice that my form felt better today than I remember the last time I ran the road; almost smoother than it previously had.  If the rest of the week plays out this same way I won't regret using the TM when it gets smoggy again. 

I decided to do the treadmill workout from last week on the road today. It all went well up until the last half mile.  I did 1 mile warm up, 4 x 1 mile @ 7:00-7:30 pace w/90 sec recoveries, and 1 mile cool down.  My splits were: 7:23, 7:22, 7:19, 7:22.  On the final half mile I felt the muscles in the arch of my foot starting to strain, like when you lift a lot of weight at the gym and feel sore the next day. By the end of the cool down, which was much slower than the warm up, both the bottom of my foot and muscle on the back of my right calf were soar. 

I'm not sure I understand why this happened.  I can run faster than this on the treadmill without this problem. I have even run a consistent 7:38 pace for 5 miles on the road and not had this problem. The only thing I can really think of is that the cushion in my shoe is shot at this point.  I've been running in the same Altra Instincts since September (maybe earlier) and maybe it's time to get new shoes? If anyone has any insights I would appreciate it. 

Either way, next time I need to just stop and rest when my foot starts to hurt.  Had I done that the injury might not have been that bad.