Today I got further advice on speed workouts from Clark Woolstenhulme, who reminded me of a speed training principle I had once read about but forgotten: short recovery cycles. So, today I ran (again on the treadmill due to the heat) 2 mile warmup, 1/2 at 7MPH, 2/10 at 6 MPH. After quite a few of those, I started speeding up to 7.5 MPH, or a 8:00 pace. I think I also extended the last one as well to .75 Miles, once again to get to an even 6.
This time I had started with no muscle soreness in my legs. I felt really great after this workout despite it being dificult while running it. And, I slept really well.