Mine run like they are in Kentucky Derby, WITH both wings held HIGH and out from body, flapping!
They all might run .20 feet and then stop and regroup for the next heat.
I get the feeling it is play. What is it?
It is a form of play. Birds are training their muscles and nervous system to perform which is important as they grow. You will often see spurts of it when they are released from confinement. Birds that fly more regularly do not do the running flapping bit as much but they still do it. You may also note they do similar on larger branches in tree where they seem to be treating it as an obstacle course. My small kids to similar where they look for complex paths to exert themselves on repeatedly. The chickens differ in they do not repeat as often in rapid succession.
They remind me of kindergarten to first grade girls who will be playing fairly quietly on the playground, and will suddenly run SCREAMING to another part of the playground. (Apparently you run faster when you're screaming) No reason for it. It's just what they do.