It was raining and a cold wind was blowing during my run on Saturday, and after I finished I didn't stretch. I just jumped in my car to get warm and drove home, planning on stretching at home. Of course, when I got in the house I was focused on taking a hot shower and eating breakfast, and I forgot to stretch. During the day I felt stiff, a normal feeling when I don't stretch after a run. In the evening, my wife and I took TRAX (train) into Salt Lake City to see our grand daughter and 3000 other music students play in the LDS Conference Center. We had to walk half a mile to/from the train and the Conference Center. By the time I went to bed, my right knee and lower quad were a little sore as well as being stiff.
I ran really fast during the first half of my run. I estimated I ran 10:15, but it was probably more like 9:30. I think I overdid it, and that caused my knees and quads to be slightly sore. The same thing happened last spring when I was running intervals at the local high school. I had run several half-mile intervals with a quarter mile jog in between for recovery. As I was mid-way through one interval, I planned on doing one more, but my right quad cramped. I immediately stopped, stretched the quad, and went home. It took a couple of days for that cramp to go away.
When I awoke on Sunday (yesterday), me right knee and quad felt better but were still slightly sore. When I awoke this morning, my legs felt almost normal. I decided to take today as a rest day to give my body another day to recover from my speed run on Saturday. The only soreness I've had today was when I kneel down. No soreness when I walk.
When I have soreness from a run, I never try to run through it. I consider soreness a sign that I overdid it, and I give my body extra rest so it can overcome the stress. I don't want to risk having the soreness become an injury.
I'm planning on running tomorrow. During the run, I'll be focused on my right leg, and if I start to feel soreness, I'll abort and walk back to my car. Also, I'll run at a comfortable LSD pace, probably around 11:30.