I've always had lower‑back issues, so I had to be careful with squats. There are so many pieces to a perfect squat. I studied powerlifters and adopted one key principle: neutral spine — YouTube it. I recommend no shoes or flat, firm shoes. Get under the bar, unrack, take one step back, chest up, shoulders back and down, head slightly inclined down, tuck the chin (press your head back into the bar for spine stability), push the hips forward and squeeze the glutes, brace the abs, feel grounded and drive through the heels. One physio I follow said 'toes up' gives more arch in the foot and better stability. Keep everything engaged and don't over‑arch your back or you'll overload L4/L5. Neutral spine distributes load across the discs. Good luck.