Bodyweight squat

What it is

Stand with your feet around shoulder width, toes turned out a little if that suits your hips. Sit down between your feet, keeping your heels flat and your lower back in its normal shape, as far as you can comfortably go. Stand back up by pushing the floor away.

Arms can go wherever helps — out in front is easiest for balance, folded across the chest is harder.

What it demands

Ankle dorsiflexion, and this is the usual limiter rather than anything to do with strength. If your heels lift, try standing with a book under them: if the squat immediately transforms, the restriction was at the ankle.

Enough hip range to sit between your feet rather than behind them.

Balance, and more of it than the loaded version needs. With nothing in your hands there is no counterweight, so staying over your feet while sitting deep is harder. This is the respect in which the unloaded squat is the more difficult one, and it surprises people.

What usually goes wrong

Heels lifting. Ankles, almost always.

Falling backwards at the bottom. No counterweight. Reaching the arms forward fixes it immediately.

The pelvis tucking under at the bottom. Below a certain depth the pelvis rotates and the lower back rounds. Where that point is differs between people and is set partly by the shape of your hip sockets — see the hip joint. Stopping above it is correct.

Copying someone else's stance. Hip anatomy varies enough that the stance which lets one person reach depth can genuinely restrict another.

Where it sits

The middle of the squat pattern: harder than a box squat, which gives you a target to sit onto, and in balance terms harder than a goblet squat, where the weight at your chest acts as a counterweight and lets you sit deeper.

That ordering is worth sitting with, because it runs against the intuition that adding weight always makes a movement harder. From here, the split squat moves towards one leg at a time.