Stiff legged deadlifts work virtually every muscle in your body. The focus is on lower back and hamstrings, and you should also feel a burn in your traps the next couple days. Basically squats are a great compound movement but doesn’t hit upper body like deads do. If you experience pain then drop the weight and focus on form. Never worry about how much weight you start with. Your lower back is sore because the muscle is fatigued, no meditation required. I do deadlifts on back day, some do them on leg day, but if you deadlift you shouldn’t squat and vice versa. It’s a heck of a load on your body and doing both exercising in one week is pretty tuff. Maybe rotate deads and squats week to week and see how your gains will be. I sldl 300lbs and find that each week it’s easy to add more weight. Usually your grip will fail before you back when you get used to the motion.
Don’t overdo your back either. If your bringing your muscles to failure with deadlifts you should give them the most time to recover.
The back muscles heal the slowest of all muscles and are usually the first to become overtrained. So dont overdo it or you’ll end up with some injuries.
TIDAL