【Heavy Roman Bench Sit-ups】Exercise abdominal muscles. Grab a barbell and sit on a Roman or dorsiflexion bench. Cross your arms and hold the platter against your chest. Lean back slightly until you feel pressure in your abdomen and your ankles press up against the pads of your feet. Take a deep breath. Keeping your neck and head in a natural position, lean back until your torso and thighs are almost parallel to the floor. Pause for a moment, then contract your abdominal muscles to return to the starting position.