There is nothing more functional, nothing more applicable, and nothing SAFER in training than the squat.
End of story. I don’t want to hear it. Scream whatever kind of shearing forces, compressive forces, lower back issues you want to. If you move through your day on two feet on a regular basis, you should be doing some sort of squatting.
You squat every morning getting out of bed, every time you get up from your morning constitutional, get out of the car, up off the subway seat… You squat. Shouldn’t you practice to be better, more efficient and stronger at it? Knee problems, hip issues, lower back problems; there is a variant of the squat that can and actually will help you improve. That having been said, if you have any of those issues, remember, consult a licensed professional before taking on any physically exertive activities. Learn your limitations, how to work with them and get busy improving your strength and mobility.
Pick a sandbag up off the floor. Stand up off a 6” to 12” step repeatedly. Put on a backpack full of books and squat down to touch the floor, stand up, rinse and repeat. Load a bar with your 3 rep maximal load and go to town. Whatever. There is a variant that fits your level in such a way as to challenge your fitness and coordination.
You’re working posture, coordination, legs, hips, back, shoulders, proprioception, balance…The sheer act of walking is a form of reciprocating unilateral squat. So find something, put it on the ground or some place that lends its self to easy loading and PICK IT UP!!