In cold weather, I noticed taht my right hand cold but left hand warm after outside running(over 30 minutes). The purfusion index measured at right middle finger is 1 to 5 and left middle finger is 8 to 12. I know my right side arm or hand blood circulation is bad. Does anybody know possible causes (blockage or clot)? any danger to continue running (so far heart feels normal, pulse and recovery normal)? Any suggestion to improve right side blood circulation? Thanks in advance.