A portable device, method and program product for generating a parameter related to the physical activity of a user. The device includes at least one sensor configured to measure information representative of the movement of a user. The sensor is configured to generate, on the basis of such information, a plurality of values of physical activity data. A data processing unit of the device, operatively connected to the sensor, is configured to generate at least one rate activity parameter on the basis of the plurality of values of physical activity data generated by the sensor. The data processing unit is further configured to generate the rate activity parameter in a first reference time t0 on the basis of a portion of values of the plurality of values of physical activity data generated by the sensor in a set period of time preceding the first reference time t0.
