Abstract: A wheelchair is provided. The wheelchair includes supports for supporting a user. The supports are configured to reduce or prevent ischemia or pressure sores of the user. In another aspect, a system of supports for supporting a user is presented. A group of the supports is arranged along the perimeter of the shape. At least some of the group of the supports have different vertical positions. In another aspect, the supports are arranged as a repeating pattern of shapes, the individual supports being peripherally disposed along perimeters of the shapes. The repeating pattern of shapes includes a first shape overlapping with a second shape, and some of the individual supports are disposed along perimeters of both the first and second shapes.