Just over two weeks ago, following a MT 10k I got a dull ache behind my knee the next day, put it down as just another niggle and have carried on training since - 35 mile a week including a track session. I've also done a park run on it since, and did another MT 10 K last Thursday. After a steady 10 yesterday it's got a tad more ache about it (3/10). Despite feeling it mildly during the first half mile or so of a run it very quickly disappears and I can train fully without feeling it. It just comes on afterwards and I can feel it walking upstairs or if I hop on the leg, it's not painful just a heavy ache. My concern is it just won't go, I'm worried that if I continue to train on it it will just get worse, but being a runner don't want to stop while my body is still allowing me to run! I have booked to see a physio on Friday but wondered if anybody else had had a similar experience and what the outcome was?