Performance intensity zones are disclosed. An apparatus comprises one or more processors, and one or more memories storing instructions, that, when executed by the one or more processors, cause the apparatus to: obtain performance intensity data measured from a user with at least one measurement sensor during a first activity and/or a second activity; and classify the performance intensity data in relation to a plurality of predetermined performance intensity zones, wherein each performance intensity zone is predetermined by a first numerical range for the first activity, and a second numerical range for the second activity, wherein the first activity and the second activity are different types of sports or different types of physical activities.