Stand facing away from a low bar, with supine grip and your feet behind it, use something on your feet to stop them from moving, be it a wall, a friend's foot or anything else. Pull with your arms to bring your back closer to the bar and then arch your back so that your elbows are on top of it.
legs, calves, femoral, quadriceps
buttocks, calves, femoral, quadriceps
buttocks, femoral, quadriceps
chest, triceps, shoulders, core