Can't run dream

I think this is a recurring theme. I'm out walking or even jogging around, this time in a city. I start going down a dark street with no one there. I see two thugs behind me coming at me meaning no good and I start to run, but I can't run. My legs start to buckle up and I can barely skip or walk. I've got to use my arms to move myself from one girder to the next door, throught the next unmanned store until I'm back out on a crowded street. Then I wake up....