Abstract: A wearable fitness heart rate monitor comprising an earpiece comprising a sensor unit having a light emitting element and a light receiving element, wherein a portion of an ear is positioned therebetween, wherein the light emitting element emits light into the portion of the ear positioned intermediate the light emitting and light receiving elements, the light receiving element detects the intensity of light passing through the portion of the ear positioned intermediate the light emitting and light receiving elements, and the sensor unit comprises means for outputting an electrical signal based thereon; processor means, coupled to the sensor unit, for processing the electrical signal and determining a heart rate therefrom; and a display, coupled to the processor means, for displaying the heart rate.