Strange. I thought I'd feel all fresh and lively on the treadmill tonight, since I hadn't really run for a couple of days. Wednesday's short run in the snow was so slow as to be more of a walk. When I got going, I felt stiff and kind of heavy-legged. It never went away the whole 6.43 miles.
The only thing I can think is that all the snow shoveling took its toll. I'd been aware of some upper body aches - particularly my left arm - associated with the scooping, but after I started running I could tell that my left leg was not as strong as my right. I had to concentrate to keep my form (you don't want to lose form on the treadmill; one misstep and you're shooting across the room in reverse). Thinking back I realized I spent most of my 3 hours of shoveling throwing loads behind me and up to the left. That had to be it.
I still managed a 9:20 pace for the distance, good enough to be counted as a tempo run. I'm seriously thinking about signing up for a half marathon April 2. I'll decide in the next day or two.