A method for estimating a cardiac pre-ejection period of a user, comprising: measuring, from a user by using a plurality of cardiac sensor devices, electrocardiogram measurement data, a first set of cardiac measurement data measured at a first location of the user's body a first distance from the user's heart, and a second set of cardiac measurement data measured at a second location of the user's body a second distance from the heart, the second distance different from the first distance, wherein the electrocardiogram measurement data is clock-synchronized with the first set of cardiac measurement data and second set of cardiac measurement data; determining, in the electrocardiogram measurement data, a first set of time instants associated with electric heart activations; determining, in the first set of cardiac measurement data, a second set of time instants associated with detections of blood pulses at the first location, the blood pulses resulting from the electric heart activations; determining, in the second set of cardiac measurement data, a third set of time instants associated with detections of the blood pulses at the second location; forming a set of scatter points on the basis of at least the second set of time instants and the third set of time instants and performing a fitting for the scatter points, wherein the scatter points are provided as a function of a time difference between time instants of the second set and time instants of the third set that are associated with the same heart activation, and wherein said fitting is described by a parameter which is the value of the fitting at a point where the time difference is zero; and computing the cardiac pre-ejection period from said parameter describing the fitting. measuring, from a user by using a plurality of cardiac sensor devices, electrocardiogram measurement data, a first set of cardiac measurement data measured at a first location of the user's body a first distance from the user's heart, and a second set of cardiac measurement data measured at a second location of the user's body a second distance from the heart, the second distance different from the first distance, wherein the electrocardiogram measurement data is clock-synchronized with the first set of cardiac measurement data and second set of cardiac measurement data; determining, in the electrocardiogram measurement data, a first set of time instants associated with electric heart activations; determining, in the first set of cardiac measurement data, a second set of time instants associated with detections of blood pulses at the first location, the blood pulses resulting from the electric heart activations; determining, in the second set of cardiac measurement data, a third set of time instants associated with detections of the blood pulses at the second location; forming a set of scatter points on the basis of at least the second set of time instants and the third set of time instants and performing a fitting for the scatter points, wherein the scatter points are provided as a function of a time difference between time instants of the second set and time instants of the third set that are associated with the same heart activation, and wherein said fitting is described by a parameter which is the value of the fitting at a point where the time difference is zero; and computing the cardiac pre-ejection period from said parameter describing the fitting.