US Patent 7172538 Exercise apparatus

An exercise apparatus includes a compact resistance unit that houses a pneumatic cylinder. The cylinder is connected to a pulley wheel that moves at least toward the cylinder. A main cable extends about a portion of the pulley wheel. One end of the main cable is fixed to the unit housing and the other end is attached to a pulley block of a block-and-tackle mechanism. A user cable extends through the block-and-tackle mechanism and is connected to a handle. The pneumatic cylinder resists movement of the handle away from the unit.