Got to ask some of the runners: I have been running on the treadmill a lot lately. About an hour a day. Last week, I sort of injured my knee because at the end of my session I sprint (apparently a bad idea I have found out on a treadmill) and I ended up with a tight, uncomfortable feeling knee. Nothing awful but I just didn't want to worsen it so I stopped running and used the elliptical for a while. It didn't worsen it but it didn't help either. So I rested the knee for a week even though all the trainers at the gym said the elliptical would be fine. So yesterday I went back and ran for an hour and it is stiff again. I wouldnt use the word painful so uncomfortable will have to suffice. Maybe it is pain but I have high tolerance so I dont know. Any advice as to what to do? Should I rest it longer than a week or maybe see someone. The stiffness is right inside the knee.