Abstract: A portable exercise device that uses a single centrally located bungee to provide equal tension on both sides of a user's back. A seat attachment strap secures the device to a seat back. In one embodiment, an optional pad worn by the user is secured to a tension strap which is attached at its ends to the bungee. The tension strap is held in place on the seat attachment strap by retaining straps mounted on the seat attachment strap. To exercise the abdominal muscles, the user leans forward causing the single tension cord to exert equal pressure on the side straps thereby exercising the abdominal muscles. By reversing position, the user may exercise back muscles by leaning backward, or exercise chest and arm muscles by pushing against the seat back with the user's arms. An alternative embodiment uses a chest strap that is centrally attached to the tension strap by a centrally located attachment strap. Another alternative embodiment attaches the tension strap directly to the chest strap.