A hula hoop is disclosed. In this hula hoop, the tubular hoop body 10 has an annular, polygonal or floral profile and contains a fluid filler 20, such as a liquid- or solid-phase fluid filler, within its cavity 30 while leaving an empty space in the cavity 30, thus being improved in its functional effect when used for physical exercise or in play due to a dynamic movement of the filler 20 within the cavity 30 during a rotating action of the hoop body about the body of a user. In the hula hoop of this invention, the fluid filler 20 is selected from water, brine, metal balls having a predetermined diameter, infrared radiation particles, and particular magnets. In addition, the fluid filler may consist of solid particles and liquid. In an embodiment, the hoop body 10 is fabricated using a plurality of modules, designed to be assembled and disassembled.