A strength machine designed for exercising the muscles of the widest back (the parallelogram muscle and the spine extensors). The cooperating muscles are the muscles of the posterior group of the shoulder girdle. The structure of the device is made of a flat-oval section with dimensions of 125x60x3. The stack covers are made of profiled sheet metal. The machine has a 7-step pneumatic seat position adjustment. The applied pneumatic actuators allow for easy adjustment of the elements by the exerciser without having to leave the device. The stack is equipped with a magnetic load selector. The upholstery elements have been adapted to the anatomical shapes of the exerciser, which contributes to the comfort and safety of use.