Workout between training to run

I have non-running cross cardio built into my race training schedules. I basically do anything that is cardio and isn't running or walking. For m this includes ARC trainer, stationary bike, inline skating, stair mill (not the stair stepper, the one that's like a forever escalator), and the elliptical.

Basically I try to stay low impact so even if some of the same muscle groups are getting worked, it's easier on my body while I'm doing it.

I found that when I added those days in (two out of six days of working out each week) I reduced the amount of time I spent injured or sore.

Walking is fine. Swimming or jogging or biking or weight lifting woud be fine, too. Pretty much anything but more running.

Its actually the joints and tendons that need a break more than the muscles themselves. Running kind of pounds the joints, whereas walking is pretty benign. If you start getting any aching anywhere, especially your joints, back off and get more rest.