Patent ID: 7033307

Claim:
An exercise device including an inflatable or solid body comprising: a first end; a second end disposed opposite the first end; a lower convex ground-engaging surface at least part of which is curved outwardly; and an upper surface that includes a first region defining a concave seat-accommodating recess adapted and configured to accommodate a user's buttocks, and a second region defining a convex back-supporting portion adapted and configured to accommodate a user's back thereby allowing a pre-stretch and full contraction of the user's abdominal muscles, wherein the concave seat-accommodating recess is located so that the user, upon changing his/her center of gravity or weight distribution on the upper surface, causes a different portion of the convex ground-engaging surface to contact the ground, and wherein the convex back-supporting portion is located adjacent the second wherein the convex lower ground-engaging surface is curved outwardly in a first direction extending between the first and second ends, and is substantially linear in cross-section taken along a second direction that is transverse to the first direction.