Interactive electronic method of didactic training for changing the postural behaviour of a user of a set of furniture (111,121,131) in a seated position during a sustained activity comprising static or dynamic exertion of at least one part of the body, this method utilizing a database relating to parameters (A, B, C) for the positions of several determined articulated areas (101, 102, 103) of the body and to a plurality of positions, called typical positions, (A1 BAC1 to A3B3C3) of the body that can be achieved during said sustained activity by modifying said parameters, said method comprising one or more iterations of the following steps by a computer: - measuring an elapse time starting from a determined cycle start time, subsequent to said user sitting on or within said set of furniture; - detecting (211, 311) when a time threshold is reached that is predetermined in relation to said database and as a function of any optional preceding iterations; - generating a signal and/or an item of alert information (213, 214, 217) requesting (203, 204) said user to carry out at least one determined movement of at least one of said articulated areas with his real body said movement leading, during said sustained activity, from a first typical position to a second typical position from said database; - detecting a movement or a change in the position of the body of the user by detection means, by connection to a cushion for detecting the position of the user on a support part of a set of furniture, said cushion being placed on the seat and being equipped with several pressure sensors distributed over its surface, and comprising means for communicating with a system implementing said method, so as to detect the location of the pressure of the user's pelvis on the seat, and possibly the direction of this pressure; and - assessing the compliance of the user's reaction through his real body with said request, and recording data showing said compliance. - measuring an elapse time starting from a determined cycle start time, subsequent to said user sitting on or within said set of furniture; - detecting (211, 311) when a time threshold is reached that is predetermined in relation to said database and as a function of any optional preceding iterations; - generating a signal and/or an item of alert information (213, 214, 217) requesting (203, 204) said user to carry out at least one determined movement of at least one of said articulated areas with his real body said movement leading, during said sustained activity, from a first typical position to a second typical position from said database; said movement leading, during said sustained activity, from a first typical position to a second typical position from said database; - detecting a movement or a change in the position of the body of the user by detection means, by connection to a cushion for detecting the position of the user on a support part of a set of furniture, said cushion being placed on the seat and being equipped with several pressure sensors distributed over its surface, and comprising means for communicating with a system implementing said method, so as to detect the location of the pressure of the user's pelvis on the seat, and possibly the direction of this pressure; and - assessing the compliance of the user's reaction through his real body with said request, and recording data showing said compliance.