Knees seem to feature frequently on this forum and I'd like to include mine in the discussion, particularly their maintenance. They've seen a bit of service but bone is not yet grinding on bone. On the way to graduation, I got used to a bit of sorenesss on the days between runs but generally they settled down nicely over the weekend. I had a bad period when I had run too far and particularly down a steep road, where I think impact caused the problem. Then an odd experience: last week I ran for 30 min. and found the next day the knees had had ball-bearings fitted and were perfect. After two days, however, when I spent a few hours at a desk and also drove the car for 80 miles or so, I found I had very sore knees. There is some improvement after a bike ride of no more than three miles today. Parkrun no. 2 may not be this Saturday, as planned. Is there a routine to maintain knees in good nick, excluding extreme exercises?