Abstract: A timing device for use in athletic workouts which measures the passage of short intervals of time such as the recovery periods between successive sets of exercise is disclosed. The present timing device is contained in a housing which may be worn on an elastic band about a user's thumb and actuated by a single finger on the same hand. In one embodiment the timing device includes a sliding interval selector switch that enables the user to select preset time intervals of fifteen, thirty, forty-five, and sixty seconds. The interval selector switch actuates a count-down timer which transmits a signal to a miniature speaker to produce an audible alarm, or in the alternative, to a vibratory device advantageous to visually or hearing impaired users. In an alternative embodiment the timing device includes a microprocessor having memory and computing functions which permit desired time intervals to be programmed by the user.