"In one study, Swedish researchers found that exercise, including jogging, may even be beneficial. Felson describes how researchers took one group of people at risk of osteoarthritis and had them engage in exercise, including jogging. The other group didn't exercise. After imaging the joints of the participants in both study groups, they found that the biochemistry of cartilage actually appeared to improve in those participants who were running. Felson says that suggests that "running is actually healthy for the joint."An audio of the article is also available. Check it out!
"...if you have a relatively normal knee and you're jogging five to six times a week at a moderate pace, then there's every reason to believe that your joints will remain healthy."