Abstract: The present invention describes an apparatus and associated method of use that ensures that the sensor contained within the strap of a chest strap type heart rate monitor remains directly over the heart thereby providing the user with the most constant and reliable heart rate data. In one embodiment an attachable harness is fitted with loops that fit over the strap of a typical chest strap type heart rate monitor. The harness then fits over the shoulders of a user and prevents the sensor within the strap of the heart rate monitor from downward slippage due to activity of the user.