A biofeedback device and the reflected infrared sensor used thereby are described herein that can be mounted on or integrated with eyewear such as swimming goggles. The biofeedback device includes a heart rate measuring apparatus comprising a reflected infrared sensor, a microcontroller comprising one or more filters and one or more amplifiers, a power source in electrical communication with the heart rate measuring apparatus, and a user interface. The reflected infrared sensor is positionable to detect heart rate from the temporal artery in the head. Heart rate is then communicated to the user by one or more tactile, auditory, or visual signal elements, such as a light-emitting diode display mounted within the goggles so as to be visible to the user while swimming.
