My knees have given me problems and I found that a bit of light bicycling limbers them up. Starting this past winter, I even 'bicycle' a bit in the basement on a rudimentary ($25 used) exercise bike, 5 minutes morning and evening.
I used to bicycle a lot! The problem(s) with my knees, specifically my left knee, is when I'm unable to move it. It doesn't seem to matter how far I run, jump, bike, or skip for that matter, but if I don't move it around every 10-20 minutes, it will swell and start to collapse when I put weight on it.
It was bad enough after four years in the 82nd (two tours in Iraq) but then, LESS THAN A YEAR after I got out of the Army, I had to go and put my Harley into a wall at 60 mph on I30 in Downtown Dallas... Hasn't been the same since.... LOL.