A system for adjusting the firmness of a substrate configured to support a subject includes a first rod configured to be movable by a mechanism, a second rod parallel to and spaced from the first rod a distance that spans a majority of a dimension of the substrate, and flexible straps extending between the first rod and the second rod and attached to the first rod and the second rod at respective ends of each flexible strap. The mechanism is configured to move the first rod in a first direction to increase tension on the flexible straps and move the first rod in a second direction to decrease tension on the flexible straps. The mechanism can be manually operated by the subject or can be a motor that is controlled by a controller.

A pressure sore prevention mattress is provided alternating pressure points on the body of an occupant that is easily transformable between two stable configurations. The four-layer mattress construction has a top foam pad, a webbing layer, a dynamic layer of deformable panels trapezoid-shaped four-bar mechanisms that deform to produce an undulating pattern of peaks, and a base. Panel geometry can determine peak height. The mattress has a spatially hollow geometry that allows natural air convection through the breathable top foam pad to enable drying of moisture as well as the use of forced air convective drying or cooling. The mattress can be transformed from one configuration to the other while the occupant is on the mattress.

A pressure sore prevention mattress is provided alternating pressure points on the body of an occupant that is easily transformable between two stable configurations. The four-layer mattress construction has a top foam pad, a webbing layer, a dynamic layer of deformable panels trapezoid-shaped four-bar mechanisms that deform to produce an undulating pattern of peaks, and a base. Panel geometry can determine peak height. The mattress has a spatially hollow geometry that allows natural air convection through the breathable top foam pad to enable drying of moisture as well as the use of forced air convective drying or cooling. The mattress can be transformed from one configuration to the other while the occupant is on the mattress.

Mattresses including a chassis core including a rigid or semi-rigid base sheet; a plurality of flat springs spaced apart from one another in parallel rows, wherein each one of the plurality of flat springs comprises a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and wherein a center of an arc defined by the arcuate member is fixedly attached to the rigid base sheet; a body support disk disposed on each one of the first and second terminal ends. The body support disk supports the load of an individual. In some embodiments, the body support disk is pivotably connected to each terminal end.

Mattresses including a chassis core including a rigid or semi-rigid base sheet; a plurality of flat springs spaced apart from one another in parallel rows, wherein each one of the plurality of flat springs comprises a first terminal end, a second terminal end, and a flexible arcuate member extending from the first terminal end to the second terminal end, and wherein a center of an arc defined by the arcuate member is fixedly attached to the rigid base sheet; a body support disk disposed on each one of the first and second terminal ends. The body support disk supports the load of an individual. In some embodiments, the body support disk is pivotably connected to each terminal end.

A pressure sore prevention mattress is provided alternating pressure points on the body of an occupant that is easily transformable between two stable configurations. The four-layer mattress construction has a top foam pad, a webbing layer, a dynamic layer of deformable panels trapezoid-shaped four-bar mechanisms that deform to produce an undulating pattern of peaks, and a base. Panel geometry can determine peak height. The mattress has a spatially hollow geometry that allows natural air convection through the breathable top foam pad to enable drying of moisture as well as the use of forced air convective drying or cooling. The mattress can be transformed from one configuration to the other while the occupant is on the mattress.