Abstract: Platform blocks for use in exercising applications are provided. A platform block generally includes a body having a top surface and a bottom surface, and defining a length and a width. The block also includes a plurality of protrusions extending upwards from the top surface of the body along opposing edge portions of the top surface of the body, and openings defined in the bottom surface of the body and arranged in multiple rows. Each opening has a width dimension. The openings in two adjacent rows of the multiple rows of openings in the bottom surface of the body each have a width dimension that is greater than the width dimension of the other openings defined in the bottom surface of the body. As such, the platform block may be used in stacking arrangements with other platform blocks having different sizes.