A method for computing the heart rate value of an user, including detecting a time-dependent optical waveform including a pulse induced by the heartbeat with an optical pulse sensor attached to the user, detecting of a time-dependent accelerometer waveform by an inertial sensor arranged in proximity of the optical pulse sensor, computing of frequency components of the time-dependent optical waveform by a mathematical transform, computing of frequency components of the time-dependent accelerometer waveform by the mathematical transform, first removing of computed frequency components of the time-dependent accelerometer waveform that are below a pre-defined threshold, second removing the computed frequency components of the time-dependent optical waveform that are matching the computed frequency components, third removing the computed frequency components after the second removing that are below a pre-defined threshold, and choosing one of the computed frequency components from the third removing as the heart rate.
