Abstract: An improved pulse rate monitoring system for detecting and displaying the heart beat of a subject while exercising or performing other activities. The subject invention comprises a pair of infrared emitters adapted to be positioned on either side of a thin appendage of the body, such as the septum of the nose or the upper part of an ear. The emitter light paths are modulated by changes in the superficial blood volume in these areas, causing corresponding changes in the output of these emitters as sensed by an infrared detector. The emitters are power strobed to provide a pulsed sensor output which is processed by electronic means to provide both analog and digital displays for use by the exerciser. The unit further comprises a visual pulse output which blinks on and off at a rate corresponding to the exerciser's heartbeat.