A wrist-worn apparatus comprising: a wrist strap (200A, 200B) for attaching the apparatus to a wrist of a user; a physical activity-related measurement sensor interface; a fingerprint sensor; a display; one or more processors; and one or more memories including computer program code; the one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus at least to: receive fingerprint data (400/402/404/406/408) from a finger of the user with the fingerprint sensor; and identify (420, 410/412/414/416/418) the fingerprint data (400/402/404/406/408) as matching with one finger of the user on the basis of a comparison between the fingerprint data (400/402/404/406/408) and reference data of a plurality of fingers of the user stored in the memory; characterized in that the apparatus is further caused to: identify a rotary movement of the finger of the user on the fingerprint sensor; identify a direction of the rotary movement either as a clockwise rotary movement or an anticlockwise rotary movement; and select a function of a physical activity-related measurement based on the identified finger, the identified rotary movement, and the identified direction of the rotary movement, wherein the rotary movement implements a sliding type continuous control of a user interface element displayed on the display. a wrist strap (200A, 200B) for attaching the apparatus to a wrist of a user; a physical activity-related measurement sensor interface; a fingerprint sensor; a display; one or more processors; and one or more memories including computer program code; the one or more memories and the computer program code are configured to, with the one or more processors, cause the apparatus at least to: receive fingerprint data (400/402/404/406/408) from a finger of the user with the fingerprint sensor; and identify (420, 410/412/414/416/418) the fingerprint data (400/402/404/406/408) as matching with one finger of the user on the basis of a comparison between the fingerprint data (400/402/404/406/408) and reference data of a plurality of fingers of the user stored in the memory; receive fingerprint data (400/402/404/406/408) from a finger of the user with the fingerprint sensor; and identify (420, 410/412/414/416/418) the fingerprint data (400/402/404/406/408) as matching with one finger of the user on the basis of a comparison between the fingerprint data (400/402/404/406/408) and reference data of a plurality of fingers of the user stored in the memory; characterized in that the apparatus is further caused to: identify a rotary movement of the finger of the user on the fingerprint sensor; identify a direction of the rotary movement either as a clockwise rotary movement or an anticlockwise rotary movement; and select a function of a physical activity-related measurement based on the identified finger, the identified rotary movement, and the identified direction of the rotary movement, wherein the rotary movement implements a sliding type continuous control of a user interface element displayed on the display. identify a rotary movement of the finger of the user on the fingerprint sensor; identify a direction of the rotary movement either as a clockwise rotary movement or an anticlockwise rotary movement; and select a function of a physical activity-related measurement based on the identified finger, the identified rotary movement, and the identified direction of the rotary movement, wherein the rotary movement implements a sliding type continuous control of a user interface element displayed on the display.