Sunday Tracksmith long run. Had a Gu, ran to the house, and about 4.5 miles in almost shipped my shorts, walked/ran as much as I could to the house, but after a bathroom stop I was fine (pretty sure that wasn't due to the Gu). The run got going, and the top group got fast quick. Dropped off that group and took a 2nd Gu at the Marathon Sports tent, and grabbed some water till a slower group showed up. Ran with them, and the group dwindled until I turned back solo, one of the guys kept going farther down the river. I guess I ran pretty well coming back solo, maintained pace, then stopped again at the MS tent, chatted with the guy for a bit, then got back going and finished up 20 with a lap around the block. My stomach was feeling pretty weird throughout the run, planned to take another Gu coming back along the river, but I just wasn't feeling it.