Abstract: An inflatable pad combined with an air control system for producing periodic inflation and deflation of that pad. The pad is elongated and has at least two separate passages extending from one end portion of the pad to the other, such passages also having interlaced transverse portions extending in directions across the pad. Each passage has a pair of terminal openings, one at each end of the pad, for the flow of air under pressure, such flow being controlled by a valve which not only alternates in directing air to inflate one passage and then the other, but also alternates the direction of inflation so that each passage is inflated alternately from its opposite ends. In one embodiment, the valve operates to positively exhaust one passage while the other is undergoing inflation, the exhaust air being recirculated and utilized by the compressor which serves as the source of pressurized air.