For a long time, my default cruising speed while running was 7.0 miles per hour. I’d go to the gym, do a five-minute warm-up at 4.0 mph, cruise at 7.0 mph, and then end with five minutes at 4.0 mph again.
This was a boring chore, and it was hard. I’d run for 60 minutes, and it was a challenge — even before I had to re-start my efforts after having been sidelined with a crushed ankle nerve.
On a lark last week, I bumped my cruising speed up to 7.3 mph … and wow! What an effect. My breathing was easier, I felt better, and life was great. I actually enjoy running again, and only because I added a mere 0.3 mph to my speed.
I think it boils down to respiratory effort. Breathing tends to be automatic, not conscious, so when I run, my breathing is based on a multiple of my footfalls — usually, inhale in three steps, and exhale in three steps, for a six-step cycle. At 7.0, my respiratory effort was not consistent with my pace, so my whole effort was inconsistent and excessively labored. But at 7.3 … it’s fun again. 🙂