An exercise device for a person, comprising at least two substantially rigid rails, each rail having an outer surface, and inner surface, and at least one peripheral edge connecting the outer surface to the inner surface. The at least one peripheral edge includes at least one axle slot formed therein. At least one substantially cylindrical axle has two ends and is adapted for rotatably and removably receiving at least one substantially cylindrical roller thereon. Each end of each axle is adapted to be captured within one of the axle slots of one of the rails. Each roller has a peripheral surface and a maximum diameter. Each axle is spaced a distance from an adjacent axle of at least the maximum diameter of the rollers, whereby each roller may rotate freely on the at least one axle. The exercise device is able to support a person lying on his back on the rollers on a flat surface.