1. A portable apparatus comprising: a first interface configured to input speed data of a user or location data of the user from a positioning unit utilizing external reference points; a second interface configured to input motion data of a user from a self-contained activity determining unit; and a processing unit configured to constitute, if the first interface only inputs the location data, speed data from the location data, select filtering characteristics based on the motion data, fitter the speed data with the selected filtering characteristics, and determine physiological data of the user with the filtered speed data.