Abstract: A device for exercising abdominal muscles by intermittent stretching and relaxing, and for massaging internal organs in the abdominal and thoracic cavities functions by applying adjustable intermittent pressure inwardly and upwardly to the surface of an exerciser's abdomen. The exercise device comprises a body belt fastened around a user's waist and having an opening covered with an expandable inwardly-facing pocket positioned over the user's abdomen. An inflatable air-tight bag located within and attached to the pocket is connected to a hand-operated bellows-air pump, the pump being suspended from the body belt and resting on the user's thighs when in use. At rest, the air-tight bag is collapsed and lies flat within the pocket; hand pressure against the bellows-air pump forces air up into and inflates the bag so that it protrudes through the pocket opening and exerts pressure inwardly and upwardly against the abdomen and forces the abdominal muscles to be stretched into the abdominal cavity.