Attach a pair of resistance bands to a door anchor. Place the door anchor at the bottom of a door. Attach a handle to the other ends of resistance bands. Stand facing away from the door and bend knees and bend over through hips with back flat close to horizontal. Keep your feet shoulder length apart and arms straight and hold the handles with with overhand grip between your legs.
Raise torso backup until reaching the straight standing up position and repeat.
Avoid pulling upward through the shoulders; all of the motion should originate through the hips.