The invention relates to a coupling and method in a heart-rate measuring apparatus. The coupling in the heart-rate measuring apparatus (10) comprises means (1, 2, 3, 4, 5) for measuring heart rate and means for wireless data transmission (7). According to the invention, the heart-rate measuring device (10) comprises means (1, 2, 3, 4, 5) implemented by analog electronics for defining the maximum value of the heart-rate signal, or a parameter proportional to it.