Hi, I'm a teenage female and I have been running for 3 years. I dont know how you define poor circulation or how you test that but i have cold feet and hands and my legs feel heavy, tired... almost a tingly feeling in my legs at rest, as if my blood is pooling in my legs. I have consulted many doctors and have not received an answer that I'm satisfied with yet. A recent diagnosis that made the most sense to me was that I have tight hip flexors from running and weaker hamstrings compared to dominant quads (as most females biologically have). However apart from stretching, I have not found a solution to it. This if very frustrating for me and has plagued me increasingly over time. If you find out anything more about this please let me know.