Anchor the bar, hug it close, squat with zero spinal compression.
Keep the bar pinned to your chest. The arc of the landmine helps keep you upright.
Hugging the loaded end of the bar at your chest while the other end anchors to the floor puts you on a gentle arc that leans you back into your heels, so staying upright is almost automatic. That upright torso keeps the work on the quads through full depth with the glutes finishing the stand, and it does it all without a bar compressing your spine. It earns its place as a squat that teaches great mechanics and trains legs hard on days your back needs a break.
For quad work and learning mechanics, it is excellent, the arc keeps you upright and honest. You will eventually run out of loading room compared to a barbell on your back, at which point it becomes a volume and technique tool rather than your main strength lift.
The load is held at your chest and the anchored arc encourages a tall torso, so there is no bar compressing your spine and far less forward lean. That combination takes most of the lower back complaint out of squatting.
Far enough that the bar sits comfortably at your chest with a slight backward lean into your heels. Too close and the bar crowds you at the bottom, too far and you are fighting to hold it up, adjust until the arc feels like support.
