I cannot be certain of the cause but at a guess I would say that I first started noticing it a week or so afterr I had a fall
onto pavement whilst running (I was wearing knee
-pads at the time, so it was more of an impact fall, rather than a wound).
More Info : the pain does not appear when I passively flex e.g. a quadriceps stretch.
I am 21, have a BMI less than 25, athletic, male. I have no history of joint pains or problems, nor does anyone in my family.