Patent ID: 7300392

Claim:
A balance board adapted for balance training on top of a spherical rolling fulcrum, comprising: an upper footstep surface and a lower bearing surface; and a progressive series of hoop sub-frames adapted for depending from the bearing surface with respect to a common center of geometry and enclosing progressively smaller framed-in areas of the bearing surface, respectively, within progressively smaller framed-in crown-cavities thereby defined, respectively, ranging between extremes of a major sub-frame and a minor sub-frame; wherein the framed-in area of the bearing surface by the major sub-frame is either flat or domed; wherein at least all but the major sub-frame are selectively removable from the platform for clearing way for the progressively smaller framed-in crown-cavities; and whereby selectively utilizing the minor sub-frame over, conversely, exclusion thereof in favor of any of the progressively larger sub-frames, with all relatively smaller sub-frames excluded as well, progressively changes the level of difficulty for trainees standing on the upper footstep surface with the spherical rolling fulcrum crowned by the balance board within the selected sub-frame; said sub-frames being adapted to permit said spherical rolling fulcrum to roll freely sandwiched between said balance board and a ground surface unless stopped against any portion of any sub-frame.