Think of using your abs to control the space between your ribs and the front of your pelvis, and don’t let them get further apart as you move.
Step back onto the bench while keeping your pelvis square.
Space your feet so that at the bottom position your forward knee is at about 90 degrees, your forward shin is vertical and the trailing leg knee is just off the ground and slightly behind your hips. Your ankle should rest on the edge of the bench.
Don’t let your pelvis roll open as you lower to the bottom position.
Keep your weight through your forward heel.
Squat upward while keeping your forward knee tracking straight over your toes and your abs tight.
Don’t let your ribs flare or arch your lower back at the top.