Method of route planning for physical training, wherein the heart rate of the subject should be kept within a permitted range. Prior to route planning, map data including starting and target points and altitude data are stored. A load profile is created by measuring the heart rate of the subject along routes of different steepness and storing the data in an electronic table, taking into account the required effort and whether the subject could have partially regenerated. The route planning includes searching and selecting a possible route, dividing the route into segments of steepness, and determining the costs based on the steepness data. The cost represents the load when the subject takes that section. Next, expected heart rate is calculated and it is determined whether it will remain in the permitted range along the whole first route. If the heart rate will be in the permitted range, the route is permitted, if not, the steps are repeated for subsequent possible routes where the heart rate in the associated route will remain in the permitted range.
