If you have knee pain, here's a quick test to know if it could be coming from friction and roughness on the back of your kneecap.
While sitting, put your hand on your knee then straighten and bend it.
If you feel a click, pop, crunchy, grinding kind of feeling under your hand when you do that, you know you have roughness on the back of the kneecap.
You just need to take the steps to decrease the friction between the knee cap and groove in the thigh bone that it's supposed to slide smoothly up and down. The first step is having good quad and ITB flexibility to allow the kneecap to slide with less friction. The second step is to use more of a "hip dominant" squat technique where you don't let your knee move forward past your toes. This technique decreases the mechanical stress of squatting, sitting down/coming back up to stand, as well as with going up stairs.
Knee pain that's caused by too much kneecap friction is a cumulative issue...many little bits of friction add up to cause a lot of pain.
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