Method for detecting biomechanical and functional parameters of the knee in a situation of performance stress, which comprises: a step for the set up of video recording means (1); a step for the set up of multiple optical markers (4) at specific landmark anatomic points (PA) of the foot and of the knee of a person; a step for the set up, at the plantar surface of the foot, of baropodometric means (5); a step for the acquisition, by means of the video recording means (1), of images of at least one reference action, and a step for the detection, by means of the baropodometric means (5), of baropodometric parameters; a step for calculating, from the baropodometric parameters, the coordinates of the center of pressure (COP) of the foot and of the constraining reaction force (FV) acting on the foot; a step for calculating a force arm (BF) given by the distance between the center of pressure (COP) and a reference point (PR) of the knee; a step for calculating a biomechanical parameter indicative of the valgus moment, derived from the vector product (PV) of the force arm (BF) and the constraining reaction force (FV).