Why can I run for 6 miles without any problems, but standing still in one place for more than 10 minutes makes my knees sore? [closed]

Question

I frequently run, both outdoors and on treadmills, often around 3-6 miles. This feels great, both during and after. However, for about two years now my knees have been bothering me: a sort of mild pain around my kneecap plagues me whenever I stand for extended periods of time. This is problematic during e.g. my work (in a lab) or during cooking. I have really come to hate it.

On top of this the tendon above my kneecap sometimes seemingly 'catches' and snaps into place when bending my knees more than 90 degrees, though this is painless.

I am 22 years old and very fit and healthy apart from this. I have stretched and foam rolled the shit out of my quadriceps, hamstrings and calves but this does not rid me of my pain.

Advice/experiences/comments would be greatly appreciated.

Answer 1

Like the comments, it's impossible to say exactly what is happening over the internet, but, you're also asking for experience, and here is mine:
It could be that your knees just aren't used to standing. I used to sit down for long periods of the day (I was young and very fond of playstation), and one summer I got a job in a shop where I was standing most of the day - obviously, because my knees/legs weren't used to this, it gave me some trouble to begin with, but after some time it corrected itself, as my body got used to prolonged standing.

Also, you might want to check out this:
Why does standing for too long make knees sore?

As well as this:
https://www.quora.com/Why-is-it-harder-to-stand-still-than-to-walk