@ehBeth,
That makes sense to me, not a fitness guru but often in the past a reader about it.
Ragman, hah, my jog was 4 mph. See, I was close re it being equiv to a fast walk.
I'm interested in Dlowan's base question, about the effect on the immune system re exercise at the end of, say, flu, or even a cold. I'm interested pro or con.
I also remember a lot of stuff about not letting too many days go by lolling about, re loss of (what?) conditioning. But I don't remember that one should just go full force right away. It's been a while, so I figure there is research data out there.