The invention provides an exercise apparatus with a hemispherical support frame and a rigid ball mounted to the support frame with a low-friction bearing system in between the ball and the support frame so that the ball is freely rotatable in any direction. In one embodiment, the bearing system comprises a plurality of ball bearings and a retainer. The present invention also provides for an exercise system with two omnidirectional rolling apparatuses and a band that tethers the pair of apparatuses. The present invention also provides for methods of using the apparatus and system to perform isotonic exercises.