After careful examination and experimentation, I have determined that my sock is the culprit. Either my feet have grown or my socks have shrunk because the end of the sock shwoops down and presses on my toe. Apparently, after 17 miles my toe has had enough of the sock pressure and revolts.
I went to my local running store yesterday to pick a replacement. This is dangerous territory. If I get a sock that is too big, then it will bunch up under my foot and cause a blister on the bottom of my foot... that would be a catastrophe. A sock that is too thin may not protect my foot from rubbing. I've tried the two layer socks and they are not for me. After 20 minutes, this is what I picked out:
They are Smartwool PhD Running Socks. At $12.49, they may very well be the most expensive pair of socks I have ever bought. They say The Highest Degree of PERFORMANCE on them, so I figured I would try them out. I ran 6 miles with them today and they were great! I was worried that they would be hot since they are Smartwool, but they seemed fine.
The real test will my 19 miler coming up on Thursday. The weather forecast looks perfect with a low of 28 and a high of 46.
I had figured that long distance running would be hard and painful. I didn't realize, though, how many little details had to be worked out. Does your hydration bottle jiggle up and down when you run? Does your GU fall out of your pocket? Does the iPod case you wear around your arm keep slipping down? Do your headphones make your ears bleed after hours and hours of wear? All of these annoying little things can take lots of time and money to work out. If you don't figure them out, they will slowly drive you crazy and sap all of the joy out of your run.
I'm keeping my fingers crossed that my toe and my new socks get along. 19 miles will be hard enough without thinking about my socks!