Device for working specifically the abdominal muscles in a staged, global, symmetrical and asymmetrical manner, while protecting the back and encouraging diaphragmatic breathing.The invention concerns a device permitting the toning up of the abdominal muscles and the gradual prolonging of effort.It is made up of a lumbar band fixed to two rings divided into three levels by two teeth, braces fixed at together with a strap. When the user pulls the strap inserted in the ring at a chosen level and holds his stomach in while taking a breath, the device supports, in a staged manner, the work of the abdominal muscles, protects the back and aids diaphragmatic breathing.This device according to the invention is particularly intended for beginners and for people suffering from lumbar pain and obesity.