Measuring the heart rate we can analyse the cardiac profile of a particular sport (Derevenco, 1998) and we can use the heart rate as a guide to plan our exercise intensity because it is in a direct linear relationship with oxygen consumption (American College of Sports Medicine, 2005). Using a heart rate monitor allows us to assess the dynamic changes that occur during physical activity in a heart rate profile (Burke & Polar Electro Inc., 1998). The system we use for our research include one cardiac monitoring belt, Polar brand, one smartphone with Bluetooth reception and specific software for analysis and the interpretation of heart rate data (SportsTracker Pro for Android and SportTracks for Windows 7). There are many systems that record heart rate during physical activity but their importance is given by the mobility that users have in terms of control and recorded data processing. We believe that the main advantages of our system are the high compatibility between system components and the high mobility to use and to transfer data from a software to another.