Abstract: An abdominal exercise system including an isometric flex-board and a rear-support. The isometric flex-board includes an exterior-surface and an interior-surface, a right-side, and a left-side; with the left-side and the right-side each including slot-openings. The rear-support includes an outside-surface, an inside surface, a left-portion, and a right-portion; with the left-portion and the right-portion each including adjustment-straps that are insertable into the slot-openings on the right-side and the left-side of the isometric flex-board to removably couple the rear-support and the isometric flex-board together and provide adjustability to the abdominal exercise system for a user. The isometric flex-board and the rear-support, when coupled together, are wearable about an abdominal area of the user to provide resistance to the abdominal area to provide a muscle exercise to the user by the user flexing the abdominal area against the resistance.