A method of measuring the heart rate of a human being by a heart rate measuring device, the method being performed using a heart rate measurement device, the method comprising: • receiving a stream of signals containing ECG signals, • selecting a reference QRS complex from said stream of signals, wherein a local amplitude maximum occurring in a first predetermined time window is selected as the R peak of said reference QRS complex, • characterising the electrical signal characteristics of said reference QRS complex by taking amplitude-time samples of said reference QRS complex, • detecting and characterising a first QRS complex from said stream of signals which is immediately adjacent to said reference QRS complex in the time domain by taking amplitude-time samples of said first QRS complex for performing template matching to determine waveform similarity with said reference QRS complex, said first QRS complex being selected upon satisfying a first set of predetermined criteria of:- (i) satisfying a predetermined threshold level of waveform similarity with said reference QRS complex, (ii) occurring within a second predetermined time window from said reference QRS complex, said second predetermined time window being a time window defined by upper and lower heart rate limits of a human being, (iii) having a local amplitude maximum the amplitude of which is within a predetermined range of the R peak amplitude of said reference QRS complex, • evaluating the instantaneous heart rate from said first QRS complex and said reference QRS complex. • receiving a stream of signals containing ECG signals, • selecting a reference QRS complex from said stream of signals, wherein a local amplitude maximum occurring in a first predetermined time window is selected as the R peak of said reference QRS complex, • characterising the electrical signal characteristics of said reference QRS complex by taking amplitude-time samples of said reference QRS complex, • detecting and characterising a first QRS complex from said stream of signals which is immediately adjacent to said reference QRS complex in the time domain by taking amplitude-time samples of said first QRS complex for performing template matching to determine waveform similarity with said reference QRS complex, said first QRS complex being selected upon satisfying a first set of predetermined criteria of:- (i) satisfying a predetermined threshold level of waveform similarity with said reference QRS complex, (ii) occurring within a second predetermined time window from said reference QRS complex, said second predetermined time window being a time window defined by upper and lower heart rate limits of a human being, (iii) having a local amplitude maximum the amplitude of which is within a predetermined range of the R peak amplitude of said reference QRS complex, (i) satisfying a predetermined threshold level of waveform similarity with said reference QRS complex, (ii) occurring within a second predetermined time window from said reference QRS complex, said second predetermined time window being a time window defined by upper and lower heart rate limits of a human being, (iii) having a local amplitude maximum the amplitude of which is within a predetermined range of the R peak amplitude of said reference QRS complex, • evaluating the instantaneous heart rate from said first QRS complex and said reference QRS complex.