Yesterday, my barefoot run at the track was 10 intervals of 2 minutes running, 30 seconds walking; essentially doubling my running per interval but the same 20 minutes of running time overall. Today, my calves are unfamiliarly tight. It's been a long time since I've felt this sort of muscle discomfort because it's been such a long time since I've been able to work out hard enough for my muscles to protest this much. It's AWESOME! There is such a difference between self-induced pain/discomfort compared to injury pain; and the former is much more tolerable than the latter.
I think my next run will be the same workout and I'll hold off increasing intervals and running time. I think I'll give my calves a few days to heal, too before I run again. I guess my running buddy will have to settle for walking outside (now that the weather has finally warmed up a bit) rather than running.