The Finnish company Polar Electro has developed and produced a variety of sports training aids since its founding in 1977, ranging from the very first wearable heart rate measuring devices to more comprehensive modern products such as specialized watches for day-to-day exercise and sleep monitoring. To support these tools, it also provides software applications for the customer to view and manage their collected data, and among these product-service systems is the Polar Team Pro for sports team coaches to monitor multiple athletes at once. Among the types of data analyzed by Polar systems are the users’ heart rate intervals and their subsequent variability, known as R-R and HRV. While the handling and display of these values have also been present in the Team Pro web application, their widespread use within it has been limited by an existing internal implementation where the HRV is calculated on demand, rather than saved to a database and re-used. Therefore, a target has been set to improve the current system in a way that only a single calculate-and-save operation is required to make the data permanently available in every pertinent part of the application, as well as to construct the user interface elements to display it therein.