Abstract: The invention concerns a training accessory for an electronic device and a training method configured to provide training feed-back in real-time. The training accessory comprises a housing suitable for holding the electronic device (400) having a graphical user interface (401), a data interface between the accessory (1) and the electronic device (400), one or more elastically deformable holding means (20), and one or more sensors (3), including at least a force sensor in the accessory (1), the force sensor being configured to determine the force exerted by the holding means (20).