[vidarh]

For squats the one thing people need to keep in mind is it requires decent hip and posterior chain flexibility before you get to anything more than moderate weights.

Especially office workers often struggle with that. Simple test: squat all the way down without a weight without lifting your heels and without falling backwards... If you can, your mobility is pretty ok. If you can't.. Well, you should fix that.

I did the mistake of squatting with poor mobility a while when I first started out, and hurt myself before figuring that out. Took just a few weeks of stretches to fix. Incidentally the same stretches (touching toes or floor, squatting and holding the position without a weight - if you can't do it at all start by holding on to something in front of you to keep you from falling) is great if sitting a lot too.

[yedava]

I don't think 'mobility' is a factor for squats. If you think you have bad mobility, try the low bar squat where the back is more horizontal at the bottom of the squat. I have a great deal of difficulty squatting with a vertical back, but I find squatting with a more horizontal back quite natural and easy.

[vidarh]

Yes, it very much is an issue with squats for many people.

If your posterior chain is too tight, you will round your back to compensate for an inability to hold your legs in the right position while hinging your hip enough.

Low bar if anything requires you to be able to keep your back tight while hinging more at the hip.

A lot of people can't do that without a few weeks of stretches first, thanks to years at a desk.