Gentle run over a short course. No knee problems arose during or immediately after the run, but at about 3 hours after the run, began to notice moderate left knee cartilage pain.
Left cartilage sufficiently bad that needed Ibuprofen to sleep last night. Could feel it all day, the biking slightly eases it for a while, but still painful and limiting.
No problem until 3 hours, after which, fairly quickly, left knee (cartilage) in considerable pain. walk was roughly equivalent to a couple of Munros, nothing difficult.