An interesting thing is that my heart rate stayed very low for the pace I was running. It was a recovery run, so I wanted to keep my HR below 140. While running an 8:30 pace, my HR was staying around 135-138. I usually have to run near 9:00 to keep my HR that low.
I don't know what the difference was. Was it the breathing? Is my aerobic conditioning improving? Do I just feel good today? I don't know. Anyway, an awesome, if lonely, 6 miler with 6 100 meter strides at the end of the run.