Exercising of stomach muscles using backrest with convex curvature whose shape is adapted to body size of user prior to training which involves moving forwards away from backrest

摘要

When training the stomach muscles the bottom is fixed and the back is moved forwards against a counterweight on the upper chest away from a convex curved backrest (4) whose shape is adapted to the shape and size of the user prior to training. The cross-sectional shape of the backrest can be changed by inflatable/deflatable foam cushions mounted inside the backrest. A hollow chamber inside the backrest can be attached to a pressure source.