There's a new study out that exercise such as running not only does NOT increase the risk for arthritis, it may stave it off!
Here's a link to an article...
http://www.npr.org/templates/story/story.php?storyId=112556135&ps=cprsThe thing to avoid is INJURING the knees. So train, just train safely.
[I suppose people think if they don't go out and run & stuff, they reduce the risk of injury... but getting overweight and out of shape is ALSO really bad for knees, and the low back, and everything else!]
--Terri