Abstract: Disclosed exercise systems may include a wavelike body having at least two peaks and a trough therebetween extending longitudinally along a longitudinal axis and a laterally along a widthwise axis perpendicular to the longitudinal axis, the wavelike body including a core component and a surface component surrounding the core component, for example. In various embodiments, the wavelike body may have at least one aperture extending laterally therethrough for securing an elastic band. In some embodiments, the core component may be formed of a rigid foam, e.g., a Poly Foam, and the surface component may be formed a relatively softer foam, e.g., an EVA foam. In some embodiments a plurality of apertures for securing an elastic chord or ribbon may extend through a sidewall of the wavelike body. In some embodiments, at least one aperture may extend through the core component and the surface component.