Embodiments provide physiological measurement systems, devices and methods for continuous health and fitness monitoring. A wearable strap may detect reflected light from a user's skin, where data corresponding to the reflected light is used to automatically and continually determine a heart rate of the user. The wearable strap may include a motion sensor that is used to determine a motion status of the user. Based upon the motion status of the user, the system may activate light emitters on the wearable strap to determine the heart rate of the user.
