Place a flat band vertically on the seat and back of a chair. Grasp the top end of the band with both hands, sit on the band and line it up with your spine. Once seated, point your elbows up, keeping your feet flat on the floor. Move your hands down the band until it offers some resistance [A]. Inhale, then exhale and curl your spine, drawing your abs in and up [B]. Slowly return to an upright position.