Procedure for placing a prosthetic foot for running (1) for a lower limb prosthesis, formed from a J-shaped composite material and connected by a TT support (2) to a connecting piece (3) in the case of a user with a transtibial amputation, or connected by means of a TF support (2a) to a known mechanical knee (G), connected in turn to a connection piece (3a), in the case of a user with a transfemoral amputation ； said connecting piece (3 or 3a) presenting a main axis (5), which passes through a point (4) that identifies the femoral epicondyle, real in the case of the user with transtibial and virtual amputation and which coincides with the center of rotation of the mechanical knee (G) during intermediate posture, in the case of a user with transfemoral amputation； said foot presenting a morphology of such a type that a segment (9), which joins a point (7), representative of the 5th virtual metatarsal and that is a point of tangency between said foot (1) and a perpendicular ground line (6) to the main axis (5), up to a point (8), representative of the virtual heel and which is a point of tangency between the foot (1) and a straight line (10) parallel to the main axis (5), an angle is inclined α between 30 ° and 50 ° with respect to the ground line (6) and because the point (8), representative of the virtual heel, rests along an inclined line an angle ß between 20 ° and 40 ° with with respect to said main axis (5) and the main axis intersects at point (4), characterized in that in the transtibial case said procedure comprises the following steps: - placing said foot (1) in the vicinity of the support TT (2) and of the connection piece (3) carried by the user, with a provisional fixation such that the dist aged D3 between the upper free end (18) of the foot (1) and the ground line (6) along an axis (10) parallel to the main axis (5) is 440 ± 10 mm, or 410 ± 20 mm , or 360 ± 30 mm, or 320 ± 10 mm and the distance D4 of the upper free end (18) of the foot (1) from the mai
