I haven't run anything long since the Ouachita Trail 50K in April. My legs felt terrible at the end of that run, and I had to limp in on the 3-mile home stretch on a busy road...not the most fun in the world. I took a week off from running, and then slowly got back on track. I switched from the trail shoes I wore up in Arkansas to New Balance MT101 shoes, because they didn't make my knees hurt. My best guess is that by running in the MT101s, I changed my stride, and made my overpronation shoes overcompensate. All of this made me cut down on the miles I would run, because I didn't want to hurt myself.