I started running this past spring despite my disintegrated cartilage in my knees.  I have been exercising for over 20 years now and my knees have taken a beating.  I wanted to find something that "hugged" my knees while I ran.  These tights do exactly that.  They are comfortable while running and the fatigue in my knees after running have been lessened.  And for sizing...definitely get the size up from your normal size!