Abstract: The lever with slider consists of a lever (30) and a slider (35), wherein the lever (30) consists of an axle attachment (10), at least two slider guides (12) and a guides limiter (14), whereas the slider (35) consists of a slider carrier (16), slider axle (24), slider limiter (18), key of the slider axle (22) and extremities attachment (20). The invention pertains to the field of equipment and devices for developing and exercising musculature or joints by means of a force of resistance with or without measuring devices. The invention addresses two problems, the problem of the best possible transfer of the extremities movement on the exercising device/appliance, i.e. the transfer of the exercising device/appliance movement on the extremity, rehabilitation or diagnostics and the problem of the removal of a large part of the unwanted load of the joints and skeletal system of the extremity that is undergoing exercising, rehabilitation or functional diagnostics.