Tight Legs and Dead Feet

One of the things I have never been able to totally figure out, is why sometimes when my legs are worn out - my feet fall asleep and get tingly, a product I'm sure of also the feeling of tightness in my ankels and achilies. I first remember noticing this at App., and there were times it lingered for a few weeks. It's really uncomfortable, and something I just run through. I had this sensation today on my run, and while I am clear of knee problems, I am hoping that it will subside in the coming runs.

Did 7 miles at a pedestrian pace of I'm sure over 8 min pace for a good bit of the run. Not concerned with that, just trying to build for a good week of higher mileage, and working on the discipline of consistency.