The method involves changing bending or stretching resistance of a resistor depending on sensor data using an actuator, and determining the sensor data by a detection device when a joint (4) of a lower leg is used, where the detection device detects two torques, single torque and single force, two torques and single force or two forces and single torque. The sensor data of the two determined parameters are associated with each other by a mathematical operation for calculating an auxiliary variable, where the resistance of the resistor is controlled based on the variable.