I've just got back from W3R3 . Really been struggling with my left knee the past 2 runs. I had a serious motorcycle accident when i was 17 and had 5 operations and half of my thigh muscle removed. As a result my leg is approx 1/2" shorter. I'm wondering if i should try an insert in my left shoe only. The pain is just under my knee cap and hurts a lot when i start to run but gets easier during the running phase but back again during the walk. I'm hoping it's mainly due to the fact i've done little exercise in the past few years. Mainly hurt when i planted my foot down so subconsciously was running on tip toe on the left side. Must have looked hilarious . Glad i was out at 5 a.m. and not 5 p.m.!