Method, apparatus and system for estimating heart rate with a wearable device. The method includes receiving movement data and heart rate data, the movement data indicative of physical exertion of an individual associated with the wearable device, and the heart rate data measured for the individual during the same period determining an estimated human power output based on the movement data indicative of physical exertion of the individual determining a heart rate demand value for improving a heart rate estimate based on the estimated human power output and at least one adaptive parameter, wherein the heart rate estimate corresponds to the heart rate data, and the at least one adaptive parameter is adjustable based on the heart rate demand value and the heart rate estimate and determining an improved heart rate estimate for the individual based on the heart rate demand value and the heart rate estimate.
