Because this comes up so often, I see it in our classes / bootcamps and one-on-one with clients, I decided it's time to announce to the majority of people who experience back and knee pain to make sure they are looking at their cylinder, first.
When I say cylinder I am referring to the trunk, shoulders down. There are three main points of focus that I work to strengthen with all clients: the lower traps, rhomboids and lats (think about the midback muscles you use to squeeze the shoulders down and back), the abodminal group AND lower back extensors (core) and the glutes. When your cylinder is strong, the extremities are not held responsible for all stabilization which can lead to misuse and aggravation.
The core and trunk are the primary source of most of our movements, and when you focus on building your strength there, and then recruiting your strength FROM there, you're more likely to have the form that will not only get you great results efficiently, but also protect you from pain and injury.
A weak or misfiring core or glute group is not ALWAYS the cause of knee or lower back pain, but should be explored. More often than not, when a client complains of this and then I assess their movement and biomechanics, I do find weakness or inefficient recruitment of these cylinder muscles.
And as always, every single body is different. If this is not the case for you, you might be best to get a proper assessment with a professional.
Sit or stand up straight, lock in your core, move with power and grace, and have a great week.