Abstract: A wrist-worn physical activity measurement apparatus is disclosed. The apparatus includes a bracelet comprising a plurality of links, each link being formed at one side to comprise a part and at the opposite side a counterpart interlocking with a part of an adjacent link, and a flexible casing encasing the plurality of the links. The apparatus is attachable around a curvature of a wrist of a user such that the links and the adjacent links are pivotably lockable in relation to each other in order to wrap and lock around the wrist.

Abstract: A wrist-worn apparatus for measuring a user's heart activity includes an optical heart activity sensor configured to measure the user's heart activity by optical heart rate measurement; and a wrist strap adapted to physically couple the optical heart rate activity sensor against the user's skin by attaching the wrist-worn apparatus around the user's wrist. A first curved connection member is adapted to slide inside a second curved connection member, and the wrist strap includes at least one groove and a fixing claw acting as a counterpart for the at least one groove. The fixing claw is arranged to engage the at least one groove when the first connection member is slid inside the second connection member.

Abstract: In the invention there is generated a playlist of music files that controls an exercise, each of the music files being associated with at least one parameter. The parameter characterizes the efficiency of the exercise. The user may listen to the playlist while performing an exercise and may have a performance instruction through musical characteristics, such as rhythm.

Abstract: In the invention there is generated a playlist of music files that controls an exercise, each of the music files being associated with at least one parameter. The parameter characterizes the efficiency of the exercise. The user may listen to the playlist while performing an exercise and may have a performance instruction through musical characteristics, such as rhythm.