An exercise apparatus accommodates a user and a resilient and resistive pivot such as an exercise ball within its structure. The pivot may have various dimensions based on the size and needs of the user and the exercise program chosen to be performed. The shape and inner dimension of the apparatus is designed to exploit the inherent instability of pivoting exercises such as twists, rolls and lifts. Various configurations of horizontal and vertical apparatus members offer the user a wide range of gripping and leverage points. A variety of exercise positions and motions may be used with this device to increase muscle flexibility and strength.