in a method and apparatus for determining a physiological activity signal in a subject using various movement sensors that each transmit a temporal movement signal , a physiological reference signal is determined from the various movement signals that best depicts a physiological movement of the subject , the movement sensor that generates the physiological reference signal is identified as a physiological reference sensor , at least one physiological addition signal is determined from the temporal movement signals that is similar to the physiological reference signal up to a limit , and the physiological reference signal and the at least one addition signal are added to form the physiological activity signal .